Here's another fine article from The World's Healthiest Foods. I hope everyone is having a nice Memorial Day Break.
Salmon 
Delicious with exceptional nutritional value found in few other foods (omega 3 fatty acids), the lovely pink-hued salmon can be served in a variety of ways and is always a favorite among fish lovers and enjoyed even by those who are not always fond of fish. The season for the different species of salmon ranges from early summer to late fall, however, the increased production of farm raised salmon has made it available fresh in local supermarkets year round.
Salmon are incredible fish traveling thousands of miles throughout their life cycle and within two to five years returning to the very location where they were born to spawn and die. The specific characteristics and life cycles of salmon vary with each species. Their flesh ranges in color from pink to red to orange with some varieties richer in important omega 3 fatty acids than others. For example, chinook and sockeye are fattier fish than pink and chum and contain great amounts of healthy omega 3 fatty acids.
Health Benefits
Salmon is low in calories and saturated fat, yet high in protein, and a unique type of health-promoting fat, the omega-3 essential fatty acids. As their name implies, essential fatty acids are essential for human health but because they cannot be made by the body, they must be obtained from foods. Fish contain a type of essential fatty acid called the omega-3 fatty acids. Wild-caught cold water fish, like salmon, are higher in omega-3 fatty acids than warm water fish. In addition to being an excellent source of omega-3s, salmon are an excellent source of selenium, a very good source of protein, niacin and vitamin B12, and a good source of phosphorous, magnesium and vitamin B6.
Cardiovascular Benefits
The omega-3 fats found in salmon have a broad array of beneficial cardiovascular effects. Omega-3s help prevent erratic heart rhythms, make blood less likely to clot inside arteries (the proximate cause of most heart attacks and strokes), improve the ratio of good cholesterol to bad cholesterol, and prevent cholesterol from becoming damaged. (Only after cholesterol has been damaged does it clog arteries.)
Omega-3s work their magic by affecting the production of hormone-like molecules called prostaglandins. Some kinds of prostaglandins are pro-inflammatory while others, like those derived from the omega-3s in salmon are anti-inflammatory. The primary omega-3 found in salmon, EPA (eicosapentaenoic acid), is the immediate precursor of the Series 3 prostaglandins, an anti-inflammatory type that prevents platelets from sticking together and improves blood flow. A four-ounce serving of salmon contains 33.6% of the daily value for omega-3 fatty acids.
Salmon promotes cardiovascular health not only through its concentration of omega-3 fats, but also because this fish is a very good source of the B-vitamins, niacin and vitamin B12. Niacin, which is necessary for the chemical processing of fats in the body, has been repeatedly used clinically to successfully lower total blood cholesterol in individuals with elevated cholesterol levels. Vitamin B12 plays a critical role as a methyl donor. Methylation is a basic cellular process in which methyl groups are transferred from one molecule to another, resulting in the formation of a wide variety of very important active molecules. When levels of B12 are inadequate, the availability of methyl groups is also lessened. One result of the lack of methyl groups is that molecules that would normally be quickly changed into other types of molecules not only do not change, but accumulate. One such molecule, homocysteine, is so damaging to blood vessel walls that high levels are considered a significant risk factor for cardiovascular disease. Just 4 ounces of baked or broiled salmon provide 56.7% of the daily value for niacin and 54.2% of the daily value for vitamin B12. Increases Heart Rate Variability-A Measure of Heart Muscle Function
One of the ways in which consuming fish rich in omega-3 fats, such as salmon, promotes cardiovascular health is by increasing heart rate variability (HRV), a measure of cardiac function, in as little as three weeks, according to a study published in the April 2005 issue of Chest.
By providing greater variability between beats, the marine omega 3 fatty acids, EPA and DHA, reduce the risk of arrhythmia and/or sudden death.
Researchers from Atlanta, GA, Boston, MA, and Cuernavaca, Mexico, took the HRV of 58 elderly patients every other day for two months to establish an HRV baseline for each participant. For the next 11 weeks, half of the study participants took a daily 2 gram supplement of fish oil and the other half took a daily 2 gram supplement of soy oil.
Patients in both groups experienced a significant increase in HRV, with those who took fish oil achieving a greater increase in a shorter time period. Patients who received fish oil experienced increased HRV within the first 2.7 weeks, whereas it took 8.1 weeks for a significant increase in HRV to be seen in the group taking soy oil.
On the other hand, while none of the study participants experienced significant negative side effects, 41% of participants in the fish oil group reported belching, compared to 16% in the soy oil group.
"Our findings contradict the current belief in the medical community that increasing the intake of omega-3 fatty acids produces only long-term cardiac benefits," said the study's lead author, Fernando Holguin, MD, Emory University School of Medicine, Atlanta, GA. "In fact, our study group showed improvements in heart function in as little as two weeks."
"Studies like this demonstrate that there are additional approaches we can take to protect ourselves from heart attacks," said Paul A. Kvale, MD, FCCP, President of the American College of Chest Physicians. "It's exciting to see the potential for omega-3 fatty acids in improving heart function when it complements a healthy lifestyle of exercising, maintaining a healthy weight, and getting eight hours of sleep." We'd add eating healthful foods to this proactive list. Rather than pop a daily pill, we'd rather enjoy a daily "dose" of delicious salmon, soyfoods, or tuna. For recipes certain to not only increase your heart rate variability but also your delight in eating, click Recipes.
Just Two Servings of Omega-3-rich Fish a Week Can Lower Triglycerides
Triglycerides are a form in which fat is carried in your bloodstream. In normal amounts, triglycerides are important for good health because they serve as a major source of energy. High levels of triglycerides, however, are associated with high total cholesterol, high LDL (bad) cholesterol and low HDL (good) cholesterol), and therefore, with an increased risk of cardiovascular disease. In addition, high triglycerides are often found along with a group of other disease risk factors that has been labeled metabolic syndrome, a condition known to increase risk of not only heart disease, but diabetes and stroke. (Metabolic syndrome is the combined presence of high triglycerides, increased blood pressure, high blood sugar, excess weight, and low HDL (good) cholesterol.)
| Triglyceride Levels |
|---|
| Less than 150 mg/dL | Normal |
| 150-199 mg/dL | Borderline-high |
| 200-499 mg/dL | High |
| 500 mg/dL | Very High |
*Note: Triglycerides are most accurately measured after an 8-12 hour fast.
In this 6-month study involving 142 overweight men and women with high triglycerides, subjects were divided into 5 groups, one of which served as a control group, 2 of which ate 2 servings of fish high in omega-3s while also replacing their normal household fats with fat high in sunflower (Group 1) or canola oil made from rapeseed (Group 2), and 2 of which ate 2 weekly servings of white fish while also replacing their normal household fats with ones high in sunflower (Group 3) or canola oil made from rapeseed (Group 4).
Canola oil also provides some omega-3 fats, with an omega-6:omega-3 ratio of 2:1, while sunflower oil contains omega-6, but no omega-3 fats.
At the end of the study, triglyceride levels had dropped 6.6% in the omega-3-rich fish groups combined. Triglycerides dropped most-10.4%-in those consuming omega-3-rich fish and canola oil. In those eating omega-3-rich fish and sunflower oil, triglycerides dropped 2.8%. Bottomline: A healthy way of eating that incorporates at least 2 weekly servings of fish and other food sources of omega-3 fats, such as flaxseed or canola oil, may significantly lower triglyceride levels. Replacing normal household fats with flaxseed oil, in which the ratio of omega-6:omega:3 fats is 1:4, might result in an even larger drop in triglyceride levels.
Protection against Stroke
Eating fish, such as salmon, as little as 1 to 3 times per month may protect against ischemic stroke (a stroke caused by lack of blood supply to the brain, for example, as a result of a blood clot), suggests a meta-analysis of 8 studies published in the July 2004 issue of Stroke.
Data on nine independent groups participating in eight different studies found that, compared to those who never consumed fish or ate fish less than once per month, risk of ischemic stroke dropped:
- 9% in those eating fish 1 to 3 times per month
- 13% in those eating fish once per week
- 18% in those eating fish 2 to 4 times per week
- 31% in those eating fish 5 or more times each week
Eating Fish Daily Provides Substantially More Protection against Heart Attack
While as little as a weekly serving of fish lowers risk of ischemic stroke, enjoying a daily serving omega-3-rich fish provides significantly greater reduction in the risk of coronary heart disease than eating fish even as frequently as a couple of times a week, show the findings of a study published in the January 17, 2006 issue of Circulation, the journal of the American Heart Association.
Researchers in Japan followed 41,578 men and women aged 40 to 59, none of whom had cardiovascular disease or cancer when the study began, from 1990-1992 to 2001. Food frequency questionnaires completed at the beginning of the study and in 1995, provided information on weekly fish intake, which was analyzed for omega-3 content.
When individuals whose fish consumption was in the top one-fifth of participants at 8 times per week were compared to those whose intake was in the lowest fifth at once per week, they were found to have a 37% lower risk of developing coronary heart disease and a 56% percent lower risk of heart attack.
When the effect of omega-3 fatty acid intake on cardiovascular risk was analyzed, coronary heart disease risk was lowered by 42% among those whose intake was the highest at 2.1 grams per day or more compared to those whose intake was the lowest at 300 milligrams per day. Those whose intake of omega 3s was in the top fifth received a 65% reduction in the risk of heart attack compared to those whose omega 3 intake was lowest.
The authors theorize that daily fish consumption is highly protective largely due to the resulting daily supply of omega-3 fatty acids, which not only reduce platelet aggregation, but also decrease the production of pro-inflammatory compounds called leukotrienes. Lowering leukotrienes reduces damage to the endothelium (the lining of the blood vessels), a key factor in the development of atherosclerosis. "Our results suggest that a high fish intake may add a further beneficial effect for the prevention of coronary heart disease among middle-aged persons," note the study's authors.
Choose Baked or Broiled, but Not Fried Salmon to Reduce Risk of Atrial Fibrillation (Heart Arrhythmia)
Eating salmon that's broiled or baked, but not fried, may reduce risk of atrial fibrillation, the most common type of heart arrhythmia, especially in the elderly, according to a Harvard study published in the July 2004 issue of Circulation. In the 12-year study of 4,815 people 65 years of age or older, eating canned tuna or other broiled or baked fish 1 to 4 times a week correlated with increased blood levels of omega-3 fatty acids and a 28% lower risk of atrial fibrillation. Eating broiled or baked fish 5 times a week lowered risk even more- a drop in atrial fibrillation risk of 31%.
Eating fried fish, however, provided no similar protection. Not only is fried fish typically made from lean fish like cod and Pollack that provide fewer omega-3 fatty acids, but in addition, frying results in the production of damaged, free-radical-laden fats in the fish as well as the frying oil. In further research to determine if the omega-3 fats found in fish oil were responsible for fish's beneficial effects on the heart's electrical circuitry, Dariush Mozaffarian and colleagues from Harvard Medical School analyzed data on fish intake and electrocardiogram results from 5096 adults, aged 65 or older, who were enrolled in the Cardiovascular Health Study from 1989-1990.
Eating tuna or other broiled or baked fish at least once a week was associated with lower heart rate (-3.2 beats/minute) and a 50% lower likelihood of prolonged ventricular repolarisation (the period of time it takes the heart to recharge after it beats, so it can beat again), compared to those consuming fish less than once a month.
Consuming 1 gram/day of omega-3 fatty acids from fish was associated with 2.3 beats/minutes lower heart rate and a 46% lower risk of prolonged ventricular repolarisation.
Eating fish at least 5 times per week was associated with an even healthier heart rhythm. However, eating fried fish (typically sold in the U.S. as fish burgers or fish sticks) was not associated with increased blood levels of omega 3 fats or any beneficial electrocardiogram results. In fact, a previous study led by the same researcher (Mozaffarian, Am J Cardiol 2006 Jan) found that while eating baked or broiled fish was linked to a slower but more powerful heart beat and lower blood pressure, eating fried fish was associated with heart muscle motion abnormalities, a reduced ejection fraction, lower cardiac output, and higher blood pressure. Since irregular heart beats are a major precipitating factor in sudden death due to cardiac arrest, promoting a healthy heart rhythm by eating baked or broiled-not fried-fish several times a week makes very good sense. Happily, as our recipes, such as 15 Minute Salmon with Mint Salsa show, it's a quick, easy and most importantly, delicious prescription.
Fish, Fruit and Vegetables Protective against Deep Vein Thrombosis, Pulmonary Embolism
Deep vein thrombosis is a dangerous condition in which blood clots develop in the deep veins of the legs, thighs or pelvis, causing swelling and pain. An embolism is created if a part or all of the blood clot in the deep vein breaks off from the site where it was created and moves through the venous system. If the clot lodges in the lung, a very serious condition, pulmonary embolism, arises.
Fortunately, a healthy way of eating offers significant protection, as demonstrated by a prospective study over 12 years that involved almost 15,000 middle-aged adults. While those eating the most red and processed meat doubled their risk of deep vein thrombosis (DVT), those in the upper 3 quintiles of fruit and vegetable intake had a 41-53% lower risk of DVT. And those eating fish, such as salmon, at least once each week were found to have a 30-45% lower DVT risk. (Steffen LM, Folsom AR, et al.,Circulation) Practical Tip: For protection against deep vein thrombosis, increase your consumption of fruit and vegetables; eat fish at least once a week; and decrease consumption of red and processed meats.
Special Cardiovascular Protection for Postmenopausal Women with Diabetes
Eating omega-3 rich fish, such as salmon, at least twice each week significantly reduces the progression of atherosclerosis in postmenopausal women with diabetes, suggests a Tufts University study published in the September 2004 issue of the American Journal of Clinical Nutrition.
The three year study included 229 women with atherosclerosis, 42% of whom also had diabetes. Although new atherosclerotic lesions were seen in all the women, regardless of fish intake, those who consumed 2 or more servings of fish per week had significantly fewer lesions-especially if at least one serving was chosen from those high in omega-3 fatty acids, such as salmon, tuna, mackerel or sardines.
Women with diabetes eating less than 2 servings of fish experienced an average 4.54% increase in stenosis (thickening and restriction) in their arteries, compared to an average increase of only 0.06% in women eating 2 servings of any fish per week.
In diabetic women eating less than 1 serving of omega-3-rich fish per week, stenosis increased 5.12% compared to a 0.35% increase in those who ate 1 or more servings of omega-3-rich fish each week.
Eating fish rich in omega-3s is so beneficial because these fats:
- lower the amount of lipids (fats such as cholesterol and triglycerides) circulating in the bloodstream
- decrease platelet aggregation, preventing excessive blood clotting
- inhibit thickening of the arteries by decreasing endothelial cells' production of a platelet-derived growth factor (the lining of the arteries is composed of endothelial cells)
- increase the activity of another chemical derived from endothelial cells (endothelium-derived nitric oxide), which causes arteries to relax and dilate
- reduce the production of messenger chemicals called cytokines, which are involved in the inflammatory response associated with atherosclerosis
Omega 3s Help Prevent Obesity and Improve Insulin Response
Salmon is particularly beneficial not just for women with type 2 diabetes, but for men with this condition as well, due to its high content of omega 3 fats.
Research presented December 2004 at the 6th Congress of the International Society for the Study of Fatty Acids and Lipids suggests that while saturated fats appear to promote weight gain, the omega 3 fats found in cold water fish, such as tuna, reduce the risk of becoming obese and improve the body's ability to respond to insulin.
The reason why? The omega 3 fatty acid, eicosapentaenoic acid (EPA) stimulates the secretion of leptin, a hormone that helps regulate food intake, body weight and metabolism, and is expressed primarily by adipocytes (fat cells). EPA, an Omega-3 Fat found in Salmon, Reduces Inflammation
A recently identified lipid (fat) product our bodies make from EPA, called resolvins, helps explain how fish oils' provide their anti-inflammatory effects on our joints and improve blood flow.
Resolvins, which have been shown to reduce inflammation in animal studies, are made from EPA by our cellular enzymes, and work by inhibiting the production and regulating the migration of inflammatory cells and chemicals to sites of inflammation. Unlike anti-inflammatory drugs, such as aspirin, ibuprofen and the COX-2 inhibitors, the resolvins our bodies produce from EPA do not have negative side effects on our gastrointestinal or cardiovascular systems.
Salmon Slashes Prostate Cancer Risk
Swedish scientists at Stockholm's Karolinska Institutet, who have published a series of epidemiological (population) studies on cancer risk factors, have released data showing that men who eat salmon just once or more per week are at least 43% less likely to develop prostate cancer, in comparison with men who never eat salmon (Hedelin M, Chang ET, et al. Int J Cancer).
Maria Hedelin and colleagues assessed fish intake among 1,499 men diagnosed with prostate cancer and another 1,330 healthy controls. They also examined blood samples from the men and identified 5 different single nucleotide polymorphisms (SNPs) or variants in the gene that controls activation of the COX-2 enzyme, a key player in both fatty acid metabolism and inflammation.
The COX-2 gene affects inflammation by directing the production of prostaglandins from omega-3 and omega-6 fatty acids. Prostaglandins are ephemeral, hormone-like substances, some of which are pro- and others of which are anti-inflammatory. Omega-3s from fish stimulate the COX-2 enzyme to trigger creation of anti-inflammatory prostaglandins. Omega-6s, concentrated in meats, corn, safflower and sunflower oils, induce production of pro-inflammatory prostaglandins.
One of the COX-2 SNPs identified by the Swedish researchers, which is present in the majority of the population-60% of men-appears to be particularly beneficial. Among salmon eaters with this variant of the COX-2 gene, risk of prostate cancer was a whopping 72% lower than in the men who never ate salmon or other fatty fish.
Prostate cancer growth is stimulated by inflammation, so a likely explanation is that in men with this genetic variation, the omega-3s provided by salmon cause the COX-2 enzyme to produce even more anti-inflammatory prostaglandins than in other men. Bottomline: all men receive at least a 43% reduction in prostate cancer risk from enjoying salmon at least once each week, with the majority lowering their risk by 72%!
Reduce Risk of Macular Degeneration
A diet high in omega-3 essential fatty acids, especially from fish such as salmon, offers significant protection against both early and late age-related macular degeneration (AMD), show two studies published in the July 2006 issue of the Archives of Opthalmology.
In age-related macular degeneration, the area at the back of the retina called the macula, which controls fine vision, deteriorates, resulting in central vision loss and even blindness. AMD is the leading cause of blindness in people over 50, affecting more than 30 million people worldwide.
In the first study, Brian Chua and colleagues in Sydney, Australia, utilized data from the Blue Mountains Eye Study, which enrolled 3,654 men and women aged 49 and older between 1992 and 1994. Dietary questionnaires completed by 2,895 participants at the beginning of the study provided information on fatty acid intake.
Participants among the top one-fifth in terms of omega-3-rich fish consumption had a 42% lower risk of early AMD compared to those whose fish intake placed them in the lowest fifth. Enjoying omega-3-rich fish at least once a week provided a a 42% reduction in risk for early AMD.
Eating omega-3-rich fish at least three times a week was associated with a 75% reduction in late AMD.
In the second study, Johanna M. Seddon and colleagues at the Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, looked at modifiable and protective factors for AMD among elderly male twins enrolled in the National Academy of Sciences-National Research Council World War II Veteran Twin Registry. Of the 681 twins examined, 222 were found to have intermediate or late stage AMD, and 459 twins had no signs of AMD.
Current smokers had a 1.9-fold (almost double) increased risk of AMD. Even past smokers' risk was highly elevated-a 1.7 increase compared to men who never smoked.
Eating more fish, however, greatly reduced AMD risk. Among the men whose fish consumption put them among the top 25% of dietary omega-3 fatty acid intake, risk of AMD was 45% lower compared to those with the lowest fish / omega-3 intake.
Eating fish at least twice a week reduced AMD risk by 36% compared to those who ate less than one serving of fish per week. The authors noted that AMD is highly preventable simply by following a healthy lifestyle: "About a third of the risk of AMD in this twin study cohort could be attributable to cigarette smoking, and about a fifth of the cases were estimated as preventable with higher fish and omega-3 fatty acid dietary intake."
Fend Off Dry Eyes
Dry eye syndrome (DES) afflicts more than 10 million Americans. Artificial tears offer only temporary relief. Expensive prescription drugs promise help, but at the cost of potentially serious side effects.
Could Mother Nature provide a cure? Yes, suggests research published in the October 2005 issue of the American Journal of Clinical Nutrition involving nearly 40,000 female health professionals aged 45-84 enrolled in the Women's Health Study.
Researcher Biljana Miljanovic, MD, MPH, and colleagues at Brigham and Women's Hospital looked at whether essential fatty acids-the omega-3 fats (found in high amounts in cold water fish and flaxseeds), and the omega-6 fats (found in red meat, safflower, sunflower, soy and corn oils)-play a role.
They do. Women whose diets provided the highest amounts of omega-3 fatty acids had a 17% lower risk of dry eye syndrome compared with those consuming the least of these beneficial fats.
In contrast, a diet high in omega-6 fats, but low in omega-3s, significantly increased DES risk. Women whose diets supplied a high ratio of omega-6 to omega-3 fatty acids had a 2.5-fold higher risk of DES syndrome compared to those with a more balanced intake of fatty acids.
Researchers specifically looked at eating tuna fish- a main source of omega-3 fatty acids in the American diet.
Compared with women eating less than one 4-ounce serving of tuna a week:
- Women who ate 2 to 4 servings of tuna per week had a 19% lower risk of DES.
- Women eating 5 to 6 servings of tuna per week had a 68% lower risk of DES.
"These findings suggest that increasing dietary intake of omega-3 fatty acids may reduce the risk of dry eye syndrome, an important and prevalent cause of ocular complaints," Miljanovic and colleagues conclude. In addition to tuna, salmon are a rich source of omega-3 fatty acids (as are mackerel, halibut, sardines, herring, flaxseeds and flaxseed oil. Due to concerns about mercury levels in tuna, to lower your risk of DES we recommend enjoying a variety of cold-water fish and adding flaxseeds and flaxseed oil to your Healthiest Way of Eating.
Protection against Sunburn
Another benefit of omega-3s anti-inflammatory effects may be their ability to protect our skin against sunburn, and possibly, skin cancer.
Although our increased susceptibility to skin cancer is usually blamed on damage to the ozone layer, dietary changes over the last 75 years, which have resulted in excessive consumption of omega-6 fatty acids and insufficient consumption of omega-3 fats, may also be causing human skin to be more vulnerable to damage from sunlight.
Research by Dr Lesley Rhodes, Director of the Photobiology Unit at the University of Manchester, UK, suggests that eating more omega-3-rich fish, such as salmon, could lessen the inflammation induced by UV-B radiation and help prevent not only the damaging effects of sunburn, but possibly skin cancer as well.
In a paper published in January 2005 in the Journal of Investigative Dermatology, Rhodes explored the ability of omega-3s to protect epidermal and dermal skin cells against UV-B-induced triggering of tumor necrosis factor-alpha, a molecule that induces the production of the pro-inflammatory cytokine, IL-8. Both EPA and DHA significantly suppressed TNF-á-induced IL-8 secretion-by 54% in the case of EPA and 42% by DHA. In an earlier one of Dr Rhodes studies, published in the May 2003 issue of Carcinogenesis, 42 healthy volunteers were given a measured dose of ultraviolet light, then divided into two groups. One group was given a daily 4 gram omega-3 fish oil supplement, while the other group received olive oil. After three months, when their responses to ultraviolet light were again measured, the skin cells of volunteers receiving fish oil experienced significantly less DNA damage, leading Rhodes to suggest that increasing consumption of omega-3-rich fish might reduce skin cancer in humans.
Grumpy Teenagers? Salmon May Help Lower Hostility and Protect Hearts
Feeling really grumpy? Eating more cold water fish such as salmon, tuna, or sardines may help. A study published in the January 2004 issue of the European Journal of Clinical Nutrition found a statistically significant relationship between consuming fish rich in omega-3 fats and a lower hostility score in 3581 young urban white and black adults. Those with the highest intake of omega 3 fats had only a 10% likelihood of being among those with the highest hostility scores. Eating any fish rich in omega 3 fats compared to eating no omega-3-rich fish was also found to drop subjects' chances of being hostile by 12%. One reason this finding is important: hostility has been shown to predict the development of heart disease, and the young adults in this study were already also enrolled in the CARDIA (Coronary Artery Risk Development in Young Adults) study-a study that is examining how heart disease develops in adults.
Food for Better Thought
Cold-water fatty fish like salmon have often been thought of as a "brain food," not only because of their ability to navigate hundreds of miles to return to their birthplace to spawn, but because of their high concentration of omega-3 fats. The human brain is more than 60% structural fat. For brain cells to function properly, this structural fat needs to be primarily omega-3 fats such as the EPA (eicosapentaenoic acid) found in salmon. This is because the membranes of all our cells, including our brain cells or neurons, are primarily composed of fats. Cell membranes are the gatekeepers of the cell. Anything that wants to get into or out of a cell must pass through the cell's outer membrane. And omega-3 fats, which are especially fluid and flexible, make this process a whole lot easier, thus maximizing the cell's ability to usher in nutrients while eliminating wastes--definitely a good idea, especially when the cell in question is in your brain.
Epidemiological studies in various countries including the U.S. suggest a connection between increased rates of depression and decreased omega-3 consumption, and in children, the relationship between low dietary intake of omega-3 fats and ADHD has begun to be studied. A recent Purdue University study showed that kids low in omega-3 essential fatty acids are significantly more likely to be hyperactive, have learning disorders, and to display behavioral problems. In the Purdue study, a greater number of behavioral problems, temper tantrums, and sleep problems were reported in subjects with lower total omega-3 fatty acid concentrations. More learning and health problems were also found in the children in the study who had lower total omega-3 fatty acid concentrations.
Over 2,000 scientific studies have demonstrated the wide range of problems associated with omega-3 deficiencies. The American diet is almost devoid of omega-3s, except for cold-water fish such as salmon; nuts, such as walnuts; and seeds like flaxseeds. In fact, researchers believe that about 60% of Americans are deficient in omega-3 fatty acids, and about 20% have so little that test methods cannot even detect any in their blood.
A number of recently published studies suggest that frequent consumption of omega 3-rich fish can be beneficial for our mental as well as physical health.
Research published in the American Journal of Psychiatry presented data providing what the researchers described as a "robust correlational relationship between greater seafood consumption and lower prevalence rates of bipolar disorders." Consumption of 50 pounds of seafood per year - which translates to a little less than a pound or four 3.8 ounce servings of fish each week - was associated with much lower risk of bipolar disorders, which the researchers attribute to the omega 3 fats in fish.
A study published in the European Journal of Clinical Nutrition and discussed above (Grumpy Teenagers? Salmon May Help) found a significant inverse correlation between adolescent hostility and fish consumption. Urban white and black young adults who consumed the most omega-3-rich fish were 18% less likely to exhibit high hostility compared to those who did not eat fish rich in omega 3 fats. Protection against Alzheimer's and Age-related Cognitive Decline
Can eating fish high in the omega-3 fatty acids, DHA(docosahexaenoic acid) and EPA (eicosapentaenoic acid), help lessen the cognitive decline and Alzheimer's disease growing in our aging population? A growing number of studies indicate the answer to this question is a resounding "Yes."
Research published in the journal Neurology indicates a direct correlation between consumption of omega-3 rich fish such as salmon and tuna, and mid-life mental performance. The five year study evaluated 1,613 subjects ranging in age from 45 to 70 for memory, psychomotor speed, cognitive flexibility (i.e., higher order information processing), and overall cognition. Eating omega-3-rich fish several times each week was found to reduce the risk of impaired overall cognitive function by almost 20% and speed by 28%. Frequent fatty fish consumption also had a similar beneficial effect on cognition.
In contrast, a higher intake of dietary cholesterol, found in meat and meat products, was significantly associated with a 27% increased risk of impaired memory and flexibility, and higher saturated fat intake was also associated with an increased risk of impaired memory, speed and flexibility, although not significantly.
The researchers speculated that low levels of DHA (docosahexaenoic acid), one of the omega 3 fats supplied by cold water fish, may be a risk factor not only for cognitive decline but Alzheimer's disease.
A prospective trial that appeared in the Archives of Neurology, which involved 815 older adults ranging in age from 65 to 94 years, found that those who ate fish just once a week had a 60% lower risk of Alzheimer's disease compared to those who rarely or never ate fish. A report from the Framingham Heart Study published in the Archives of Neurology showed that persons whose blood levels of DHA placed them in the top quartile of values had a significantly (47%) lower risk of developing all-cause dementia than did those in the bottom quartile. Plus, greater protection against cognitive decline was obtained from consuming 2.9 than 1.3 fish meals per week. (Schaefer EJ, Bongard V, et al.).
Two additional positive studies have been published in the American Journal of Clinical Nutrition (van Gelder BM, et al. and Beydoun MA, et al.):
In the Zutphen Elderly Study, which involved 210 men aged 70-89 years (van Gelder BM, Tijhuis M, et al.), a linear relation was found between the estimated intake of DHA and EPA and prevention of cognitive decline.
A DHA+EPA intake of approximately 380 mg per day seemed to prevent cognitive decline. This amount of DHA+EPA would be found in just 20 grams (just 2/3 of one ounce) of Chinook salmon or in 100 grams (about 3 ounces) of cod.
Eating just two to three meals of fish a week would supply approximately 380 mg EPA+DHA per day.
In the Minneapolis study (Beydoun MA, Kaufman JS et al.) of 2251 men and women, risk of cognitive decline increased as levels of omega-6 (arachidonic acid) increased in subjects' cholesterol and other blood lipids, but decreased as the concentration of omega-3 fat (linoleic acid) increased in their blood fats.
Among subjects with high blood pressure and high cholesterol, cognitive decline was clearly associated with lower blood levels of omega-3 fats (DHA+EPA).
In all of these studies, fish consumption and the resulting increase in blood levels of omega-3 fatty acids significantly lessened mental decline over time.
How? A number of mechanisms have been suggested in recent studies to explain fish's protective effects against cognitive decline and Alzheimer's:
- EPA's anti-clotting and anti-inflammatory actions promote a healthy blood supply to the brain and lower inflammation.
- Since EPA and arachidonic acid are metabolized by the same enzymes, an increase in levels of EPA helps lessen the production of the pro-inflammatory compounds derived from arachidonic acid. (Arachidonic acid is a precursor of proinflammatory cytokines eicosanoids that are thought to be associated with greater cognitive decline.)
- Increasing consumption of DHA may correct the DHA deficiency in the cerebral cortex characteristically seen in patients with Alzheimer disease.
- DHA is involved in the membrane of ion channels in the brain, making it easier for them to change shape and transmit electrical signals.
- DHA is the source of an anti-inflammatory compound made in the brain called NPD1 that lessens amyloid-beta production in cytokine-stressed human brain cells.
- DHA slows the accumulation of tau, a protein involved in the development of neurofibrillary tangles, and also decreases beta amyloid formation by reducing levels of presenilin, the enzyme that separates beta amyloid from its parent protein. (Neurofibrillary tangles and beta amyloid plaques are the two types of brain lesions seen in Alzheimer's disease.)
Frank LaFerla, co-author of research published in the Journal of Neuroscience showing that DHA helps prevent the formation of neurofibrillary tangles and decreases beta amyloid formation, commented: "We are greatly excited by these results, which show us that simple changes in diet can positively alter the way the brain works and lead to protection from Alzheimer's disease pathology."
Practical Tip: To keep your cognitive edge, cut back on sources of omega-6 fats, such as beef, and corn, palm, peanut, safflower and sunflower oils, and enjoy omega-3-rich cold water fish, such as salmon, at least 3 times each week.
One More Reason Salmon Protects against Alzheimer's and Age-related Cognitive Decline
Research published in the August 2004 issue of the Journal of Neurology, Neurosurgery and Psychiatry indicates regular consumption of niacin-rich foods like salmon provides protection against Alzheimer's disease and age-related cognitive decline.
Researchers from the Chicago Health and Aging Project interviewed 3,718 Chicago residents aged 65 or older about their diet, then tested their cognitive abilities over the following six years.
Those getting the most niacin from foods (22 mg per day) were 70% less likely to have developed Alzheimer's disease than those consuming the least (about 13 mg daily), and their rate of age-related cognitive decline was significantly less. To be sure the fish you choose are those least likely to contain excessive amounts of mercury, just click on the following link: Should I be concerned about mercury in fish and what fish are safe to eat?
Omega-3-Rich Diet Improves Mood, Reduces Depression
When researchers from Ohio State University evaluated blood samples taken from 43 older adults (average age 67), they found that study participants with high ratios of omega-6 to omega-3 not only had higher levels of various compounds involved in inflammation, but were more likely to suffer from depression.
Both depression and stress promote the production of pro-inflammatory cytokines. Researchers measured a number of these pro-inflammatory compounds including tumour necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), and the IL-6 soluble receptor (sIL-6r). Symptoms of depression were assessed using the Center for Epidemiological Studies Depression Scale. Levels of pro-inflammatory cytokines increased progressively as depressive symptoms increased. But when depressive symptoms were combined with high omega-6:omega-3 ratios, levels of proinflammatory cytokines skyrocketed by up to 40% more than normal -- far beyond the 18% increase resulting from the presence depressive symptoms alone.
Chronic inflammation has already been linked to heart disease, type 2 diabetes, osteoporosis, cognitive decline and Alzheimer's. Earlier epidemiological (population) studies have also linked higher levels of pro-inflammatory cytokines with depressive symptoms. This new study suggests that a diet that is rich in omega-6 fats but includes few of the foods rich in omega-3 fats - such as the standard American diet -- promotes not only inflammation, but depression.
The positive take-away is that increasing consumption of foods rich in omega-3s, while decreasing consumption of omega-6-rich foods, can provide some protection against depression, particularly as depressive symptoms increase.
Omega-3s are found in cold water fish, nuts, such as walnuts, and flaxseeds. Alpha-linolenic acid (ALA), the omega-3 in nuts and seeds, can be converted - albeit inefficiently - in the body to the omega-3s found in fish, eicosapentaenoic acid (EPA) and docosahexaenioc acid (DHA).
EPA improves blood flow and is also suggested to affect hormones and the immune system, both of which have a direct effect on brain function. DHA is active in the membrane of ion channels in the brain, making it easier for them to change shape and transmit electrical signals, and is involved in serotonin metabolism (reduced serotonin production and/or activity is a key factor in depression).
Practical Tip: Be of good cheer. Cut back on sources of omega-6 fats, such as beef, and corn, palm, peanut, safflower and sunflower oils. Enjoy a handful of omega-3-rich walnuts and/or flaxseeds daily, and a serving of cold water fish, such as salmon and sardines, at least 3 times each week.
Cancer-Protection
Eating even small amounts of fish may protect against ovarian and digestive tract cancers. In a large study conducted in Spanish hospitals, a total of 10,149 cancer patients with 19 different types of cancer and 7,990 controls were included. The researchers determined that eating more fish correlated with a reduced risk of certain cancers. Fish eaters had less cancer in the ovaries, pancreas and all parts of the digestive tract including the mouth, pharynx, esophagus, stomach, colon and rectum.
Epidemiological and experimental evidence shows that the omega-3 fats in salmon may also exert protective effects against breast, colon, and possibly prostate cancers. Clinical studies have suggested several possible mechanisms behind these beneficial effects, including inhibiting the production of Series 2 prostaglandins (the pro-inflammatory kind) and inhibiting angiogenesis, the development of additional blood supplies that cancer cells must have for tumor growth and metastasis. Lab and animal research published in the November 2005 issue of the International Journal of Cancer, shows that the omega-3 fatty acids found in cold water fish-docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA)-curb the growth of breast cancer cells via yet another protective mechanism: by activating an enzyme called sphingomyelinase, which then generates the release of ceramide, a compound that induces the expression of the human tumor suppressor gene p21, which ultimately causes cancer cell death.
In the animal experiments, mice were fed diets rich in either omega-3 (fish oil) or omega-6 (corn oil) fatty acids, after which breast cancer cells were implanted. Three weeks later, tumor volume and weight was significantly lower in mice on the omega-3 rich diet.
Why? Dietary fatty acids are incorporated into cell membranes, and the type of fatty acids dictates how a cell responds and grows. In the lab culture experiments, when cells were treated with DHA or EPA, these fats were incorporated into cell membranes with the result that sphingomyelinase activity increased by 30-40%, and breast cancer cell growth dropped 20-25%.
Salmon may be especially protective against cancer since this fish contains not only omega-3 fats, but is an excellent source of the trace mineral selenium.
Selenium is of fundamental importance to human health. It is an essential component of several major metabolic pathways, including thyroid hormone metabolism, antioxidant defense systems, and immune function. Accumulated evidence from prospective studies, intervention trials and studies on animal models of cancer have suggested a strong inverse correlation between selenium intake and cancer incidence. Several mechanisms have been suggested to explain the cancer-preventive activities of selenium. Selenium has been shown to induce DNA repair and synthesis in damaged cells, to inhibit the proliferation of cancer cells, and to induce their apoptosis, the self-destruct sequence the body uses to eliminate worn out or abnormal cells. In addition, selenium is incorporated at the active site of many proteins, including glutathione peroxidase, the most important for cancer protection. One of the body's most powerful antioxidant enzymes, glutathione peroxidase is used in the liver to detoxify a wide range of potentially harmful molecules. When levels of glutathione peroxidase are too low, these toxic molecules are not disarmed and wreak havoc on any cells with which they come in contact, damaging their cellular DNA and promoting the development of cancer cells. Four ounces of cooked salmon provide 75.8% of the daily value for selenium.
Lower Your Risk of Leukemia, Multiple Myeloma, and Non-Hodgkins Lymphoma
Fishermen have, in epidemiological studies, been identified as having a lower risk of leukemia, multiple myeloma and non-Hodgkin lymphoma, an occupational benefit that researchers thought might be due to the fact that they eat more fish. Now, a Canadian study published in the April 2004 issue of Cancer Epidemiology Biomarkers & Prevention suggests that persons whose diet includes more weekly servings of fresh fatty fish have a much lower risk of these three types of cancer. Data drawn from a survey of the fish eating habits of 6,800 Canadians indicates that those consuming the most fatty fish decreased their risk of leukemia by 28%, their risk of multiple myeloma by 36%, and their risk of non-Hodgkin lymphoma by 29%. Overall, frequent eaters of fatty fish reduced their risk for all forms of lymphomas by 30%.
Salmon and Other Fatty Fish Highly Protective against Kidney Cancer
Consumption of fatty fish, such as salmon, offers significant protection against renal cell carcinoma, the most common form of kidney cancer, suggests evidence presented in a 15.3-year epidemiological study involving 61,433 women who participated in the Swedish Mammography Cohort Study (Wolk A, Larsson SC, JAMA).
Renal cell carcinoma (RCC), the 10th most common form of cancer with a male:female ratio of 5:3, accounts for more than 80% per cent of all kidney cancers. Although an earlier review of prospective cohort studies (MacLean et al, JAMA) did not support the hypothesis that fish consumption is protective, the authors of the new JAMA study point out that virtually all the other studies on the subject, including MacLean's, did not take into account whether the fish consumed were fatty or lean fish.(Fatty fish contain 20 to 30 times more omega-3 (DHA and EPA) than lean fish, which provide 3-5 times more vitamin D.)
When this distinction was considered, the researchers found that those who consumed one or more serving of fatty fish each week had a 44% decreased risk of RCC compared with those who consumed no fatty fish.
Plus, those who reported long-term consumption between the beginning of the study and the 10-year follow-up had a dramatic 74% lower risk.
In contrast, no association was found between consumption of lean fish or other seafood and incidence of RCC. Wolk notes,"Our results support the hypothesis that frequent consumption of fatty fish may lower the risk of RCC, possibly due to increased intake of fish oil rich in EPA and DHA, as well as vitamin D."
Fish and Whole Grains Highly Protective against Childhood Asthma
According to the American Lung Association, almost 20 million Americans suffer from asthma, which is reported to be responsible for over 14 million lost school days in children, and an annual economic cost of more than $16.1 billion.
Increasing consumption of whole grains and fish could reduce the risk of childhood asthma by about 50%, suggests the International Study on Allergy and Asthma in Childhood (Tabak C, Wijga AH, Thorax).
The researchers, from the Dutch National Institute of Public Health and the Environment, Utrecht University, University Medical Center Groningen, used food frequency questionnaires completed by the parents of 598 Dutch children aged 8-13 years. They assessed the children's consumption of a range of foods including fish, fruits, vegetables, dairy and whole grain products. Data on asthma and wheezing were also assessed using medical tests as well as questionnaires.
While no association between asthma and intake of fruits, vegetables, and dairy products was found (a result at odds with other studies that have supported a link between antioxidant intake, particularly vitamins C and E, and asthma), the children's intake of both whole grains and fish was significantly linked to incidence of wheezing and current asthma.
In children with a low intake of fish and whole grains, the prevalence of wheezing was almost 20%, but was only 4.2% in children with a high intake of both foods. Low intake of fish and whole grains also correlated with a much higher incidence of current asthma (16.7%). compared to only a 2.8% incidence of current asthma among children with a high intake of both foods.
After adjusting results for possible confounding factors, such as the educational level of the mother, and total energy intake, high intakes of whole grains and fish were found to be associated with a 54 and 66% reduction in the probability of being asthmatic, respectively.
The probability of having asthma with bronchial hyperresponsiveness (BHR), defined as having an increased sensitivity to factors that cause narrowing of the airways, was reduced by 72 and 88% when children had a high-intake of whole grains and fish, respectively. Lead researcher, CoraTabak commented, "The rise in the prevalence of asthma in western societies may be related to changed dietary habits." We agree. The Standard American Diet is sorely deficient in the numerous anti-inflammatory compounds found in fish and whole grains, notably, the omega-3 fats supplied by cold water fish and the magnesium and vitamin E provided by whole grains. One caution: wheat may need to be avoided as it is a common food allergen associated with asthma.
Description
While salmon are born in fresh water, they spend a good portion of their lives in the sea, only to navigate hundreds of miles to return to their birthplace in order to spawn. It's no wonder that these smart and intuitive fish are considered a "brain food."
Salmon are usually classified either as Pacific (Oncorhynchus family) or Atlantic (Salmo family) salmon, according to the ocean in which they are found. There is just one species of Atlantic salmon, while there are five species of Pacific salmon including chinook (or king), sockeye (or red), coho (or silver), pink and chum. Norwegian salmon, a popular type of salmon often offered on restaurant menus, is actually Atlantic salmon that is farm-raised in Norway.
The characteristics of salmon vary with the species. Their colors range from pink to red to orange. In addition, some salmon are richer and fattier than others; for example, chinook and sockeye are fattier fish than pink and chum.
History
People have been enjoying salmon as a food ever since this beautiful fish appeared in the Earth's waters--basically, since time immemorial.
Like other fish, in addition to being consumed fresh, preservation techniques such as smoking or salting were used to preserve the salmon. Smoked salmon is still considered traditional fare in the cuisines of Scandinavia and the Russian Federation.
Much of the salmon available in today's market comes from the waters of Alaska, the Pacific Northwest, eastern Canada, Norway and Greenland.
How to Select and Store
Salmon is sold in many different forms. Fresh salmon is available whole or in steak or fillet form. Salmon is also available frozen, canned, dried or smoked.
Whenever possible, choose wild rather than farm raised salmon. Research published by the Environmental Working Group (July 30, 2003) indicates that farmed salmon poses a cancer risk because it may be carrying high levels of carcinogenic chemicals called polychlorinated biphenyls (PCBs). PCBs have been banned in the US for use in all but completely closed areas since 1979, but they persist in the environment and end up in animal fat. When farmed salmon from U.S. grocery stores was tested, the farmed salmon, which contains up to twice the fat of wild salmon, was found to contain 16 times the PCBs found in wild salmon, 4 times the levels in beef, and 3.4 times the levels found in other seafood. Other studies done in Canada, Ireland and Britain have produced similar findings. For more on the nutritional differences between wild and farmed raised salmon, please see our article on this topic.
Salmon Farms Kill Wild Salmon, Study Shows
New research, conducted by PhD. student Martin Krkosek and colleagues from the University of Alberta, Canada, has established that sea lice from farms kill up to 95% of juvenile wild salmon that migrate past them.
Adult salmon are the primary hosts of sea lice. In natural conditions, adults are located far offshore when the juveniles are migrating out to sea, but fish farms put adult salmon in pens along the migration routes of juveniles, producing a cloud of sea lice through which the juveniles must migrate. Since juveniles are only one to two inches long, it takes just one or two sea lice to kill a juvenile pink or chum salmon.
The University of Alberta team concentrated on 3 migration routes along the Broughton Archipelago in British Columbia, counting sea lice on 14,000 juvenile salmon as they migrated past 7 farms along the 80 km route, and conducted mortality experiments with more than 3,000 fish.
They found an increasing number of salmon were killed over the migration season, from 9% in early spring when the sea lice population was low to 95% cent in late spring when the sea lice population was higher.
"The work is of an impeccably high standard, and will be very difficult to refute," said Dr. Andy Dobson, a Princeton University epidemiologist specializing in wildlife diseases.
"Everyone knows that only a small fraction of juvenile salmon survive to return as adults," said study co-author Dr. Mark Lewis. "The fish-farm sea lice are reducing that fraction even more."
The study's implications may be severe for wild salmon. "Even the best case scenario of an additional 10% mortality from farm-origin sea lice could push a fish stock into the red zone," said biologist Dr. John Volpe, a study co-author at the University of Victoria.
"The debate is over," said study co-author Alexandra Morton, a biologist with the Raincoast Research Society. "This paper brings our understanding of farm-origin sea lice and Pacific wild salmon to the point where we know there is a clear severe impact."
Although the study was conducted in British Columbia, the results apply globally. "This study really raises the question of whether we can have native salmon and large scale aquaculture -- as it is currently practiced -- in the same place," said Dr. Ransom Myers, a fisheries biologist at Dalhousie University. The Alberta scientists are concerned that many people may be consuming farmed fish under the false impression that they are conserving wild fish, which they say is not the case.
Another Reason to Avoid Farmed Salmon: Flame Retardants
Flame-retardant additives used widely in electronics and furniture are appearing in increasing amounts in fish, and farmed salmon contain significantly higher levels of these polybrominated diphenyl ether (PBDE) compounds than wild salmon, according to research published in the August 11, 2004 issue of Environmental Science and Technology.
PBDEs are endocrine disrupters that have been shown to have reproductive toxicity, and are also suspected to play a role in cancer formation. As with other toxins, it is thought that farm-raised salmon contain higher PBDE levels than wild due to the "salmon chow," a mixture of ground fish and oil, they are fed.
The authors of this new study, Ronald Hites of Indiana University and colleagues, analyzed the same group of 700 wild and farmed salmon collected from around the world from which the data was drawn for their initial research on other contaminants in salmon, which was published in Science in January 2004.
As was the case with the 14 contaminants described in the earlier report-which included pesticides such as toxaphene and dieldrin-the researchers found the highest levels of PBDEs, on average, in farm-raised salmon from Europe. But while European farmed salmon had the highest levels, farmed North American salmon came next with significantly higher amounts of PBDEs than were found in farmed salmon from Chile, which, in turn, were higher than the average levels seen in wild salmon.
In both farmed and wild salmon, approximately 50% of the total PBDEs were in the form of one compound: brominated diphenyl ether (BDE) 47. This chemical is associated with the Penta formulation used in polyurethane foam in furniture, which, together with another formulation known as Octa, has been banned in Europe and is being discontinued in the United States. Unfortunately, (BDE) 47 can also be derived from the breakdown of the Deca formulation, which is extensively used in Europe with no plans to discontinue its use either there or in the U.S.
Researchers both in Europe and the U.S. think the problem is not just in the "salmon chow", but the environment as a whole and that PBDEs are probably reaching the open ocean and getting into the marine food web through atmospheric deposition.
To underscore this point, Åke Bergman of Stockholm University's department of environmental chemistry, one of the first scientists to present evidence that PBDEs were bioaccumulating in humans, says he has found the PBDE levels in wild European salmon are on a par with those Hites has reported for farmed European salmon.
And the environmental contamination is not limited to Europe. Wild chinook salmon from British Columbia were found to have the highest levels of PBDE contamination of any of the salmon Hites tested. He thinks this may be due to the chinooks' tendency to feed higher in the food chain throughout their adult life, eating mainly fish, unlike other salmon species that tend to consume more invertebrates and plankton.
On the other hand, wild Alaskan Chinook tested in Hites' study contained significantly lower PBDE levels, suggesting that the waters the wild chinook inhabit are more contaminated.
Surprisingly, the PBDE content patterns seen in the world's salmon do not match up with the levels found in people; samples of blood and fat from North Americans contain levels 10 times higher, on average, than Europeans, another reason to think some other source of exposure is also at work. Bergman thinks the high U.S. levels are due to inhalation of these substances.
What you can do: Beginning September 2004, U.S. supermarkets are required to label salmon as farmed or wild. We suggest that you choose wild, rather than farmed salmon, and if purchasing chinook salmon, choose Alaskan chinook.
Farmed Salmon Found to Have a Higher Toxic Equivalency Score than Any Other Food
While the American Heart Association recommends consumption of at least 2 portions of fish per week due to well documented health benefits of consuming fish high in omega-3 fatty acids, Jeffrey Foran from the Midwest Center for Environmental Science and Public Policy, Milwaukee, US, and colleagues from various institutes were concerned that the health risks of consuming farmed salmon might outweigh the benefits.
Foran's group are the same researchers who collaborated on an earlier study (summarized above), which was published in Science in January 2004 and found farmed salmon contain substantially higher concentrations of organic contaminants, including polychlorinated biphenyls (PCBs), toxaphene, dieldrin, dioxins, and polybrominated diphenyl ethers (PBDEs).
A primary concern was farmed salmon's concentration of dioxin. Farm-raised salmon contains between 3 and 10 times more dioxin than wild salmon. So, Foran and colleagues investigated the toxicity of organic contaminants, including dioxin, in farmed salmon from Europe and America, and in wild salmon.
Dioxin congener 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is the most potent dioxin and is classified as a human carcinogen. Complex mixtures of dioxins and dioxin-like compounds (such as PCBs), are thought to increase the risk of all cancers. These chemicals also elicit a variety of other toxic effects including suppression of the immune system, learning and memory disabilities, alterations in behavior, increased risk of cardiovascular disease and diabetes, impaired prostate development, and endometriosis.
Looking at all these toxins, Foran's team concluded that the TEQ (toxic equivalency) average for farmed salmon is greater than that reported in any other food.
They recommend that U.S. farmed salmon should be consumed at rates of less than 10 portions per month. Salmon from Northern European farms should be consumed less than 4 times per month. Wild salmon can be consumed once a day. We recommend that you eat only wild salmon. Since currently more than half of all salmon consumed is farmed, it's highly likely that the salmon offered on the menu is farmed. Always ask if the salmon you are ordering in a restaurant or purchasing at your grocery is wild or farmed. Farmed salmon is predominantly Atlantic salmon, so choose Alaskan or Pacific salmon, but if in doubt, skip the fish!
Choose Sockeye Salmon for the Most Vitamin D
Vitamin D is essential for healthy bones and teeth, and its deficiency has been linked to increased risk of multiple sclerosis, depression and cancer.
Our skin cells produce vitamin D when exposed to sunlight, but persons living in more northern geographical areas, such as the Pacific Northwest or New England in the United States, persons getting very little sunlight due to indoor jobs or personal habits, including constant use of sunscreen, and persons with naturally darker skin, are at risk for vitamin D deficiency. Choosing a diet amply supplied with the foods richest in vitamin D can help, and where fish are concerned, the best source of vitamin D is sockeye salmon.
Sockeye salmon are an exceptionally rich source of vitamin D: a 4-ounce serving of baked or broiled sockeye salmon provides 739.37 IU of vitamin D. The same 4-ounce serving of chinook salmon, another excellent source of vitamin D, supplies 411 IU.
Why are sockeye salmon even more richly endowed with vitamin D than other salmon species? Because zooplankton constitute so much of their diet, and zooplankton-along with phytoplankton-are the key sources of vitamin D in the marine food chain. Zooplankton are tiny marine animals, such as larval-stage crustaceans, while phytoplankton are single-cell marine organisms.
Both types of minuscule sea life create lots of vitamin D from sunlight, and zooplankton feed on phytoplankton, building up their vitamin D content to even higher levels. Unlike most other fish and salmon species (except chum), sockeye feed largely on zooplankton through all stages of life. Chinook, on the other hand, feast on insects and sideswimmers when young, then consume a variety of fish, especially smelt and ciscoes, a type of lake herring, as they mature.
Just as with any seafood, it is best to purchase salmon from a store that has a good reputation for having a fresh supply of fish. Get to know a fishmonger (person who sells the fish) at your grocery store, so you can have a trusted resource from whom you can purchase your fish.
Fresh whole salmon should be displayed buried in ice, while fillets and steaks should be placed on top of the ice. If you are purchasing a whole fish and want to eat the skin, have the salmon scaled.
Smell is a good indicator of freshness. Since a slightly "off" smell cannot be detected through plastic, if you have the option, purchase displayed fish as opposed to pieces that are prepackaged. Once the fishmonger wraps and hands you the fish that you have selected, smell it through the paper wrapping and return it if it does not smell right.
Smoked salmon should not have dry or brown edges. In addition, avoid smoked salmon that is very shiny or is leaking moisture as it is probably not too fresh.
When storing all types of seafood, including salmon, it is important to keep it cold since fish is very sensitive to temperature. Therefore, after purchasing salmon or other fish, make sure to return it to a refrigerator as soon as possible. If the fish is going to accompany you during a day full of errands, keep a cooler in the car where you can place the salmon to make sure it stays cold and does not spoil.
The temperature of most refrigerators is slightly warmer than ideal for storing fish. Therefore, to ensure maximum freshness and quality, it is important to use special storage methods to create the optimal temperature for holding the fish. One of the easiest ways to do this is to place salmon, which has been well wrapped, in a baking dish filled with ice. The baking dish and fish should then be placed on the bottom shelf of the refrigerator, which is its coolest area. Replenish ice one or two times per day.
The length of time that salmon can stay fresh stored this way depends upon how fresh it is, i.e. when it was caught. Fish that was caught the day before you purchased it can be stored for about four days, while fish that was caught the week before can only be stored for about one or two days.
You can extend the shelf life of salmon by freezing it. To do so, wrap it well in plastic and place it in the coldest part of the freezer where it will keep for about two to three weeks.
How to Enjoy
For some of our favorite recipes, click Recipes.
Tips for Preparing Salmon:
Try to buy a whole salmon side, or filet that is from the thickest part of the fish. Skin the salmon and remove the bones before cooking if possible. This can be done easily. When removing the bones, pull them out 1 at a time going with the grain of the fish.
A Few Quick Serving Ideas:
Combine left-over cold salmon with greens and vegetables for a delicious salad.
For a twist on scrambled eggs, combine eggs with lox (smoked salmon) and onions, a classic NY delicatessen breakfast favorite.
Serve seared, or broiled salmon over whole wheat pasta. Top with a sauce made with olive oil, dill weed, lemon peel, scallions and black pepper. Look for our healthy methods of Stovetop Searing and Quick Broiling.
For a healthy appetizer, serve smoked salmon on a platter with onions, capers, lemon wedges and mini rye bread slices.
Quick Broil salmon and top with a honey, mustard sauce.
Safety
Government inspection is not mandated for seafood, so choose your fish purveyor carefully. While some fish are not considered safe for pregnant or nursing mothers or young children to eat, eating wild pacific salmon does not pose a safety concern.
Salmon and Purines
Salmon contain naturally-occurring substances called purines. Purines are commonly found in plants, animals, and humans. In some individuals who are susceptible to purine-related problems, excessive intake of these substances can cause health problems. Since purines can be broken down to form uric acid, excess accumulation of purines in the body can lead to excess accumulation of uric acid. The health condition called "gout" and the formation of kidney stones from uric acid are two examples of uric acid-related problems that can be related to excessive intake of purine-containing foods. For this reason, individuals with kidney problems or gout may want to limit or avoid intake of purine-containing foods such as salmon.
Nutritional Profile
Salmon is an excellent source of omega-3 fatty acids, vitamin D, and selenium. It is also a very good source of protein, niacin and vitamin B12 and a good source of phosphorous, magnesium and vitamin B6.
For an in-depth nutritional profile click here: Salmon.
In-Depth Nutritional Profile
In addition to the nutrients highlighted in our ratings chart, an in-depth nutritional profile for
Salmon is also available. This profile includes information on a full array of nutrients, including carbohydrates, sugar, soluble and insoluble fiber, sodium, vitamins, minerals, fatty acids, amino acids and more.
Introduction to Food Rating System Chart
The following chart shows the nutrients for which this food is either an excellent, very good or good source. Next to the nutrient name you will find the following information: the amount of the nutrient that is included in the noted serving of this food; the %Daily Value (DV) that that amount represents; the nutrient density rating; and the food's World's Healthiest Foods Rating. Underneath the chart is a table that summarizes how the ratings were devised. Read detailed information on our
Food and Recipe Rating System.
Salmon, chinook, baked/broiled
4.00 oz-wt
113.40 grams
261.95 calories | | Nutrient | Amount | DV
(%) | Nutrient
Density | World's Healthiest
Foods Rating |
|---|
| tryptophan | 0.33 g | 103.1 | 7.1 | excellent | | vitamin D | 411.00 IU | 102.8 | 7.1 | excellent | | omega 3 fatty acids | 2.09 g | 83.6 | 5.7 | excellent | | selenium | 53.07 mcg | 75.8 | 5.2 | excellent | | protein | 29.14 g | 58.3 | 4.0 | very good | | vitamin B3 (niacin) | 11.34 mg | 56.7 | 3.9 | very good | | vitamin B12 (cobalamin) | 3.25 mcg | 54.2 | 3.7 | very good | | phosphorus | 420.71 mg | 42.1 | 2.9 | good | | magnesium | 138.35 mg | 34.6 | 2.4 | good | | vitamin B6 (pyridoxine) | 0.52 mg | 26.0 | 1.8 | good | World's Healthiest
Foods Rating | Rule |
|---|
| excellent | DV>=75% | OR | Density>=7.6 | AND | DV>=10% | | very good | DV>=50% | OR | Density>=3.4 | AND | DV>=5% | | good | DV>=25% | OR | Density>=1.5 | AND | DV>=2.5% |
|
In Depth Nutritional Profile for Salmon
