Tomatoes
There are few vegetables that better mark the summer months than the sweet juiciness of a vine-ripened tomato. Although tomatoes are now available year-round, the truly wonderful qualities of tomatoes are the best when they are in season from July through September.
Tomatoes have fleshy internal segments filled with slippery seeds surrounded by a watery matrix. They can be red, yellow, orange, green, purple, or brown in color. Although tomatoes are fruits in a botanical sense, they don't have the dessert quality sweetness of other fruits. Instead they have a subtle sweetness that is complemented by a slightly bitter and acidic taste. Cooking tempers the acid and bitter qualities in tomatoes and brings out their warm, rich, sweetness.
This chart graphically details the %DV that a serving of Tomatoes provides for each of the nutrients of which it is a good, very good, or excellent source according to our Food Rating System. Additional information about the amount of these nutrients provided by Tomatoes can be found in the Food Rating System Chart. A link that takes you to the In-Depth Nutritional Profile for Tomatoes, featuring information over 80 nutrients, can be found under the Food Rating System Chart.
- Health Benefits
- Description
- History
- How to Select and Store
- How to Enjoy
- Safety
- Nutritional Profile
- References
Antioxidant Benefits of Lycopene
In the area of food and phytonutrient research, nothing has been hotter in the last several years than studies on the lycopene in tomatoes. This carotenoid found in tomatoes (and everything made from them) has been extensively studied for its antioxidant and cancer-preventing properties. The antioxidant function of lycopene-its ability to help protect cells and other structures in the body from oxygen damage-has been linked in human research to the protection of DNA (our genetic material) inside of white blood cells. Prevention of heart disease has been shown to be another antioxidant role played by lycopene.
In contrast to many other food phytonutrients, whose effects have only been studied in animals, lycopene from tomatoes has been repeatedly studied in humans and found to be protective against a growing list of cancers. These cancers now include colorectal, prostate, breast, endometrial, lung, and pancreatic cancers. While lycopene may play an important role in tomatoes' health benefits, it seems that it is not the only nutritional star integral for giving this food a red-hot reputation for health promotion; recent research discussed below in the section "Protection Due to Synergy of Tomato's Nutrients, Not Just Lycopene" describes how scientists are finding out that it is the array of nutrients included in tomatoes, including, but not limited to lycopene, that confers it with so much health value. All the while, it's still important to understand the many benefits that lycopene provides.
For the most lycopene, choose organic
Organic ketchup delivers three times as much of the cancer-fighting carotenoid, lycopene, as non-organic brands.
Lycopene has been shown to help protect not only against prostate, but breast, pancreatic and intestinal cancers, especially when consumed with fat-rich foods, such as avocado, olive oil or nuts. (This is because carotenoids are fat-soluble, meaning they are absorbed into the body along with fats.)
When Betty Ishida and Mary Chapman at the USDA Agricultural Research Service in Albany, CA, decided to investigate whether the lycopene content of purple and green varieties of ketchup was comparable to that of the traditional red, they tested lycopene levels and antioxidant activity in 13 ketchup brands: 6 popular ones, 3 organic and 2 store brands from fast-food chains.
Purple, green and red varieties of ketchup all delivered similar amounts of lycopene (although dark red ketchup contained slightly more), but a major difference was discovered between organic and non-organic brands. Organic ketchups far surpassed their non-organic counterparts' in lycopene content.
One organic brand delivered 183 micrograms of lycopene per gram of ketchup, about five times as much per weight as a tomato.
Non-organic brands averaged 100 micrograms per gram, with one fast-food sample providing just 60 micrograms per gram. Bottomline: It seems highly likely the same rationale will apply to all tomato products, so, for the most lycopene, choose the deepest red organic ketchup, tomato sauce, juice and other tomato products.
Colon Health
A study published in American Journal of Clinical Nutrition found that in patients with colorectal adenomas, a type of polyp that is the precursor for most colorectal cancers, blood levels of lycopene were 35% lower compared to study subjects with no polyps. Blood levels of beta-carotene also tended to be 25.5% lower, although according to researchers, this difference was not significant. In their final (multiple logistic regression) analysis, only low levels of plasma lycopene (less than 70 microgram per liter) and smoking increased the likelihood of colorectal adenomas, but the increase in risk was quite substantial: low levels of lycopene increased risk by 230% and smoking by 302%.
Prostate Health
Tomatoes have been shown to be helpful in reducing the risk of prostate cancer.A 14-month study published in the Journal of the National Cancer Institute underscores the importance of a healthy whole foods diet rich in tomatoes in the prevention of prostate cancer. In this study, laboratory animals fed a lycopene-rich diet and treated with N-methyl-N-nitrosourea (a carcinogen) and testosterone to induce prostate cancer had a similar risk of death from prostate cancer as rats fed a control diet. In contrast, animals fed whole tomato powder were 26% less likely to die of prostate cancer. By the end of the study, 80% of the control group and 72% of the animals fed lycopene had succumbed to prostate cancer, while only 62% of the animals fed whole tomato powder had died.
In addition to the controls and those animals receiving lycopene or tomato powder, each group was also divided into two sub-groups, one of which was given 20% less food than the other sub-group. Animals on the energy-restricted, tomato-based diet fared best of all, showing a 32% drop in their risk of dying from prostate cancer.
Researchers concluded this was due to the fact that tomatoes contain not merely lycopene, but a variety of protective phytonutrients and suggest that the lycopene found in human prostate tissue and the blood of animals and humans who remain free of prostate cancer may indicate exposure to higher amounts of not just lycopene but other compounds working in synergy with it. Study leader, Dr. Steven Clinton, Ohio State University, commented, "Our findings strongly suggest that risks of poor dietary habits cannot be reversed simply by taking a pill…if we want the health benefits of tomatoes, we should eat tomatoes or tomato products and not rely on lycopene supplements alone." In an accompanying editorial, Peter H. Gann, of the Robert H. Lurie Comprehensive Cancer Center at Northwestern University in Chicago, and Frederick Khachik, of the University of Maryland, College Park, remarked that this study supports those who advocate whole foods in the debate about whether cancer prevention is best achieved with whole foods or concentrated single compounds. They point out that carotenoids and other phytonutrients evolved as sets of interacting compounds, and that this complexity limits the usefulness of reductionist approaches that seek to identify single protective compounds.
More Studies Show Tomatoes Promote Prostate Health
A meta-analysis of 21 studies published in Cancer Epidemiology Biomarkers and Prevention confirms that eating tomatoes, especially cooked tomatoes, provides protection against prostate cancer. (Meta-analyses are considered the gold standard in medical research since, by combining the results of numerous studies, they integrate the results that occurred in different settings and include a much larger group of people, so they are thought to provide a more accurate assessment.) When the data from all 21 studies was combined, men who ate the highest amounts of raw tomatoes were found to have an 11% reduction in risk for prostate cancer. Those eating the most cooked tomato products fared even better with a 19% reduction in prostate cancer risk. Even eating just one 6-ounce serving a day of raw tomato provided some benefit-a reduction in prostate cancer risk of 3%.
Tomatoes and Broccoli Team Up to Fight Prostate Cancer
Tomatoes and broccoli-two vegetables separately recognized for their cancer-fighting capabilities-are even more successful against prostate cancer when working as a team in the daily diet, shows a study published in Cancer Research.
"When tomatoes and broccoli are eaten together, we see an additive effect. We think it's because different bioactive compounds in each food work on different anti-cancer pathways," said John Erdman, Professor of Food Science and Human Nutrition at the University of Illinois.
Starting one month before male rats were implanted with prostate tumors, Erdman and doctoral candidate Kirstie Canene-Adams fed the animals one of 5 different diets. Then they compared the cancer-preventive effects of the diets to treatment with finasteride, a drug commonly prescribed for men with enlarged prostates, or surgical castration.
The diets contained one of the following: 10% tomato, 10% broccoli, 5% tomato plus 5% broccoli, 10% tomato plus 10% broccoli, or lycopene (23 or 224 nmol/g diet).
The tomato and broccoli given as powders made from the whole vegetable to compare the effects of eating the whole food to simply consuming one active compound as a nutritional supplement- in this case, lycopene, a carotenoid found in tomatoes.
After 22 weeks, when the rats' were sacrificed and their prostate tumors weighed, the 10% tomato/broccoli combination was shown to greatly outperform all other diets, shrinking prostate tumors by 52%.
Broccoli alone decreased tumor weight by 42%, and tomato alone by 34%.
Lycopene alone (23 or 224 nmol/g diet) came in last, reducing tumor weight by 7% and 18% respectively.
Only castration-a last resort option for most men, although it resulted in a 62% reduction in prostate tumor weight-approached the level of protection delivered by the tomato/broccoli diet. Said Erdman, "As nutritionists, it was very exciting to compare this drastic surgery to diet and see that tumor reduction was similar."
"Older men with slow-growing prostate cancer who have chosen watchful waiting over chemotherapy and radiation should seriously consider altering their diets to include more tomatoes and broccoli," said Canene-Adams.
To get the prostate health benefits seen in this study, a 55-year-old man would need to consume 1.4 cups of raw broccoli and 2.5 cups of fresh tomato, 1 cup of tomato sauce or ½ cup of tomato paste daily, said Canene-Adams.
Erdman noted that this study shows eating whole foods is better than taking isolated nutrients. "It's better to eat tomatoes than to take a lycopene supplement-and cooked tomatoes may be better than raw tomatoes. Chopping and heating make the cancer-fighting constituents of tomatoes and broccoli more bioavailable," he said.
Practical Tips: While the phytonutrients in tomatoes become more concentrated when they are cooked into a sauce or paste, and more bioavailable when eaten with a little oil, those in broccoli will be greatly reduced if this vegetable is overcooked. Steam or healthy sauté broccoli no more than 5 minutes.
Also, broccoli's cancer-preventive compounds form after it has been cut, but heat denatures the enzyme necessary for this process. For optimal nutrient formation, cut broccoli florets in half or into quarters, depending on their initial size, and let sit for 5 minutes before cooking.
Broccoli and tomatoes can make a delicious team at virtually any meal or snack:
- Healthy sauté broccoli and onion, then add to your favorite breakfast omelet and serve with grilled tomatoes.
- Enjoy a bowl of tomato soup along with a salad including broccoli florets for lunch.
- Add lightly steamed broccoli florets to the tomato-paste toppings on your favorite pizza.
- Healthy sauté broccoli florets along with other favorite vegetables, such as onions and mushrooms, add to pasta sauce and use to top whole wheat pasta or brown rice.
- For a quick snack, serve raw broccoli florets along with the carrot and celery sticks, dip and crackers, and toast your prostate's health with a glass of tomato juice.
Tomatoes and Green Tea Team Up to Prevent Prostate Cancer
Choosing to eat lycopene-rich tomatoes and regularly drink green tea may greatly reduce a man's risk of developing prostate cancer, suggests research published the Asia Pacific Journal of Clinical Nutrition (Jian L, Lee AH, et al.)
In this case-control study involving 130 prostate cancer patients and 274 hospital controls, men drinking the most green tea were found to have an 86% reduced risk of prostate cancer compared, to those drinking the least.
A similar inverse association was found between the men's consumption of lycopene-rich fruits and vegetables such as tomatoes, apricots, pink grapefruit, watermelon, papaya, and guava. Men who most frequently enjoyed these foods were 82% less likely to have prostate cancer compared to those consuming the least lycopene-rich foods.
Regular consumption of both green tea and foods rich in lycopene resulted in a synergistic protective effect, stronger than the protection afforded by either, the researchers also noted.
Practical Tips: Get in the habit of drinking green tea and eating lycopene-rich foods.
- Take a quart of iced green tea to work and sip throughout the day or take it to the gym to provide prostate protection while replenishing fluids after your workout.
- Pack a ziploc bag of apricots and almonds in your briefcase or gym bag for a handy snack.
- Start your breakfast with a half grapefruit or a glass of papaya or guava juice.
- Begin lunch or dinner with some spicy tomato juice on the rocks with a twist of lime. Snack on tomato crostini: in the oven, toast whole wheat bread till crusty, then top with tomato sauce, herbs, a little grated cheese, and reheat until the cheese melts.
- Top whole wheat pasta with olive oil, pine nuts, feta cheese and a rich tomato sauce for lunch or dinner.
Pancreatic Health
One of the deadliest cancers, pancreatic cancer progresses so rapidly that individuals with the disease who are participating in studies often die before their interviews can be completed-so the benefits noted in the following study of a diet rich in tomatoes and tomato-based products are especially significant.
In this 3-year Canadian study, published in the Journal of Nutrition, individuals with pancreatic cancer were age and gender matched with individuals free of the disease. After adjustment for age, province, body mass index, smoking, educational attainment, dietary folate and total caloric intake, the data showed men consuming the most lycopene had a 31% reduction in their risk of pancreatic cancer. Among persons who had never smoked, those whose diets were richest in beta carotene or total carotenoids reduced their risk of pancreatic cancer by 43% and 42%, respectively.
How Tomatoes Promote Optimal Health
Research by Dr. Joseph Levy and colleagues from Ben-Gurion University of the Negev, Beer-Sheva, Israel, may have identified the unique mechanism through which lycopene protects against cancer: activating cancer-preventive phase II enzymes. When the researchers incubated breast and liver cancer cells with lycopene, the carotenoid triggered the production and activity of certain phase II detoxification enzymes that other carotenoids, including beta-carotene, astaxanthin, and phytoene, did not. Since much epidemiological evidence indicates that lycopene acts synergistically with other phytonutrients to give tomatoes their protective effects, and recent studies have shown that eating tomato products prevents cancer more effectively than taking lycopene alone, the researchers concluded that other carotenoids stimulate phase II enzymes via different pathways from that used by lycopene.
Significant Anti-Oxidant Protection
In addition to their center-stage phytonutrient, lycopene, tomatoes are packed with traditional nutrients that have been shown in many studies to be helpful for all of the above conditions. For example, tomatoes are an excellent source of vitamin C and vitamin A, the latter notably through its concentration of carotenoids including beta-carotene. These antioxidants travel through the body neutralizing dangerous free radicals that could otherwise damage cells and cell membranes, escalating inflammation and the progression or severity of atherosclerosis, diabetic complications, asthma, and colon cancer. In fact, high intakes of these antioxidants have been shown to help reduce the risk or severity of all of these illnesses.
In addition, tomatoes are a very good source of fiber, which has been shown to lower high cholesterol levels, keep blood sugar levels from getting too high, and help prevent colon cancer. A cup of fresh tomato will provide you with 57.3% of the daily value for vitamin C, plus 22.4% of the DV for vitamin A, and 7.9% of the DV for fiber.
Reduction in Heart Disease Risk
More good news for those at risk of atherosclerosis, or just trying to avoid it, is that tomatoes are a very good source of potassium and a good source of niacin, vitamin B6, and folate. Niacin has been used for years as a safe way to lower high cholesterol levels. Diets rich in potassium have been shown to lower high blood pressure and reduce the risk of heart disease. Vitamin B6 and folate are both needed by the body to convert a potentially dangerous chemical called homocysteine into other, benign molecules. High levels of homocysteine, which can directly damage blood vessel walls, are associated with an increased risk of heart attack and stroke. All of these nutrients work together to make tomatoes a truly heart-healthy food. In a cup of tomato, you'll get 11.4% of the daily value for potassium, 5.6% of the DV for niacin, 7.0% of the DV for B6, and 6.8% of the DV for folate.
Research showing tomatoes' cardiovascular benefits continues to accumulate. A study led by Dr. Howard Sesso and published in the American Journal of Clinical Nutrition further supports Dr. Sesso's earlier studies, reported in the Journal of Nutrition, which found that women with the highest intake of lycopene-rich tomato-based foods had a significantly reduced risk of heart disease. This 4.8 year study, a prospective case-control trial involving almost 40,000 middle-aged and elderly women in the Women's Health Study, found that as the women's blood levels of lycopene went up, their risk for cardiovascular disease dropped. Study subjects were divided into four groups in order of increasing blood levels of lycopene. A 34% reduction in cardiovascular disease risk was seen in women in the top two groups, but even women in the second highest group were still 22% less likely to develop cardiovascular disease compared to women in the lowest group. After excluding women with angina, those whose plasma lycopene levels were in the three highest groups were found to have a 50% reduced risk of cardiovascular disease compared to those with the lowest blood levels of lycopene.
Tomato Juices May Reduce Blood-Clotting Tendencies
Tomato juice can reduce the tendency toward blood clotting, suggests Australian research published in the Journal of the American Medical Association. In this study, 20 people with type 2 diabetes were given 250 ml (about 8 ounces) of tomato juice or a tomato-flavored placebo daily. Subjects had no history of clotting problems and were taking no medications that would affect blood clotting ability.
After just 3 weeks, platelet aggregation (the clumping together of blood cells) was significantly reduced among those drinking real tomato juice, while no such effect was noted in those receiving placebo.
In an interview, lead researcher Sherri Lazarus explained, "Diabetes is a multi-faceted disease with problems such as glucose intolerance, high blood pressure, high cholesterol and high triglycerides, and the less talked about hyperactive platelets.
Platelets are the parts of blood responsible for the preservation of healthy blood vessels. When the health of blood vessels is impaired, as in the case of diabetes, platelets stick to the lining of the vessel wall, which, over time, can lead to the development of cardiovascular disease. Aggregation is the clumping together and clotting of platelets. We looked at how susceptible the platelets were to clotting before and after the people with type 2 diabetes had taken tomato juice."
Although dietary strategies have been developed to address other known cardiovascular risk factors, currently there is no dietary strategy aimed at reducing high platelet activity. For persons with type 2 diabetes, tomato juice may be just what the doctor should order. While of special benefit for those with type 2 diabetes who are at increased risk of cardiovascular disease, the blood thinning effects of tomato juice are noteworthy for anyone at higher risk of blood clot formation. Persons with high cholesterol, those whose work involves traveling long distances, who have recently undergone a surgical procedure or who smoke would benefit. But be sure to choose a low-sodium tomato juice; many "regular" tomato juice products are loaded with artery-unfriendly sodium.
Protection Due to Synergy of Tomato's Nutrients, Not Just Lycopene
Recent research clearly shows that tomatoes' protective effects against prostate cancer and cardiovascular disease are due not simply to their lycopene content, but result from the synergy of lycopene with other phytonutrients naturally present in whole tomatoes.
In addition to an animal study published in the Journal of the National Cancer Institute that found whole tomato powder was significantly more effective than lycopene alone in preventing the onset of prostate cancer (summarized under prostate cancer) other research is now demonstrating that lycopene may play only a minor role in tomatoes' heart health benefits.
Animal research from Japan, published in the British Journal of Nutrition, suggests that a tomato-rich diet-which they call an anti-thrombotic diet-is a convenient and effective way to prevent thrombotic diseases such as heart attack and stroke.
Research conducted by Howard Sesso and colleagues from the Harvard School of Public Health shows that women who consume the most tomato-containing products, particularly concentrated foods such as tomato sauce and pizza, have a reduced risk of cardiovascular disease.
Sesso and his team analyzed the results of a prospective cohort study of almost 40,000 middle-aged and older women who completed food frequency questionnaires over a 7.2 year period. At the beginning of the study, all participants were free of cardiovascular disease. During the study, 719 of the women developed cardiovascular disease. After Sesso et al. controlled for factors such as age, smoking, family history and other health indicators, the data revealed that women who consumed seven to ten servings of tomato-based foods each week (tomato juice, tomato sauce, pizza) had a 32% lower risk of developing cardiovascular disease than women who ate less than 1.5 servings of these tomato products each week. Sesso et al. had decided to do this study to see if lycopene, a carotenoid abundant in tomatoes that other research has linked to a reduced risk of prostate cancer, was also associated with a reduction in cardiovascular disease risk. In this study, however, while consumption of tomato products, particularly tomato sauce and pizza, provided cardiovascular protection, dietary lycopene intake alone was not strongly associated with a reduction heart disease risk. The researchers theorize that other phytonutrients found in oil-based tomato products in addition to lycopene are responsible for the cardiovascular benefits seen.
Tomato Juice-a Natural Anti-Inflammatory
Italian researchers, publishing in the Journal of Agricultural and Food Chemistry have reported that a daily glass of tomato juice (Lyc-o-Mato) can lower one of the primary markers of inflammation-TNF-alpha-by almost 35% in less than one month.
Oxidative stress (the production of excessive amounts of free radicals within cells) and the resulting recruitment of inflammatory compounds such as TNF-alpha have been linked to virtually all chronic degenerative diseases, including atherosclerosis (hardening of the walls of the arteries), cardiovascular disease, cancer, osteoporosis and Alzheimer's disease. Lyc-o-Mato tomato juice contains a mix of potent antioxidants including 5.7 mg of lycopene, 1 mg beta-carotene, 3.7 mg of phytoene, 2.7 mg of phytofluene, and 1.8 mg of the alpha-tocopherol fraction of vitamin E.
The placebo-controlled, double-blind crossover trial divided 26 young healthy volunteers into two groups. In three 26-day segments, Group One first was given a placebo juice (same taste and flavor but no active compounds), then nothing, then a daily glass of Lyc-o-Mato. Group 2 got Lyc-o-Mato first, then nothing, then placebo. Study subjects continued to eat their normal, unrestricted diet. TNF-alpha levels decreased by 34% after 26 days' consumption of the tomato drink while no changes in TNF-alpha levels were seen after placebo.
Helping You Bone Up
Tomatoes are a very good source of vitamin K. The 17.8% of the daily value for vitamin K that is found in one cup of raw tomato is important for maintaining bone health. Vitamin K1 activates osteocalcin, the major non-collagen protein in bone. Osteocalcin anchors calcium molecules inside of the bone. Therefore, without enough vitamin K1, osteocalcin levels are inadequate, and bone mineralization is impaired.
Feeling Stressed? How about a Nice Cup of Gazpacho?
A Tufts University study published in the Journal of Nutrition shows that daily consumption of gazpacho (two bowls of 250 mL/day, corresponding to 72 mg of vitamin C, for two weeks) significantly increased blood levels of vitamin C and decreased biomarkers of oxidative (free radical) stress and inflammation.
Gazpacho, a Mediterranean vegetable soup that typically combines tomato, cucumber, and sweet pepper along with olive oil, onion, garlic, wine vinegar and sea salt, is replete, not only with vitamin C, but a variety of other nutrients associated with a reduced risk of chronic disease, including other antioxidants, folic acid, and fiber.
This study focused on gazpacho's effect on vitamin C levels and biomarkers of oxidative stress and inflammation in 12 healthy subjects (both men and women). Within just 7 days, blood levels of vitamin C had increased 26% in the men and 25% in the women and remained elevated throughout the study. Also, when they were measured on day 14, a number of markers of oxidative stress and inflammation had decreased: F2-isoprostanes, PGE2, and MCP-1 dropped in men and women, and uric acid decreased significantly in men and slightly in women. While the focus of this study was gazpacho's vitamin C, researchers noted that other nutrients present in the soup may have synergistically contributed to its positive effects. For example, the plasma concentration of carotenoids also increased. The researchers' final conclusion: increasing vegetable consumption could improve human health.
More Help against Colon Cancer, Diabetes, and Migraines
So how else can tomatoes help? The folate in tomatoes can also help to reduce the risk of colon cancer. In addition, tomatoes are a good source of riboflavin, which has been shown to be helpful for reducing the frequency of migraine attacks in those who suffer from them. A good intake of chromium, a mineral of which tomatoes are a good source, has been shown to help diabetic patients keep their blood sugar levels under control. In addition to the 6.8% of the daily value for folate already mentioned above in relation to its protective actions against cardiovascular disease, a cup of tomatoes contains 5.3% of the DV for riboflavin, and 7.5% of the DV for chromium.
Tomatoes are a great vegetable loaded with a variety of vital nutrients. They also make a wonderful addition to a heart-healthy and cancer-preventing diet. So whether it is by tomato soup, tomato sauce, tomato chunks in salad or tomato slices on a sandwich, increasing your intake of tomatoes is an excellent step towards excellent health.
The tomato is the fruit of the plant Lycopersicon lycopersicum and is a member of the Solanaceae, or Nightshade family. The name that this fruit was given in various languages reflects some of the history and mystery surrounding it. Lycopersicon means "wolf peach" in Latin and refers to the former belief that, like a wolf, this fruit was dangerous. The French call it pomme d'amour, meaning "love apple," since they believed it to have aphrodisiacal qualities, while the Italians call it pomodoro or "golden apple," owing to the fact that the first known species with which they were familiar may have been yellow in color.
Regardless of its name, the tomato is a wonderfully popular and versatile food that comes in over a thousand different varieties that vary in shape, size and color. There are small cherry tomatoes, bright yellow tomatoes, Italian pear-shaped tomatoes, and the green tomato, famous for its fried preparation in Southern American cuisine.
Only the fruits of this plant are eaten since the leaves contain toxic alkaloids (see Safety section below). Tomatoes have fleshy internal segments filled with slippery seeds surrounded by a watery matrix. They can be red, yellow, orange, green, purple, or brown in color.
Although tomatoes are fruits in a botanical sense, they don't have the dessert quality sweetness of other fruits. Instead they have a subtle sweetness that is complemented by a slightly bitter and acidic taste. They are prepared and served like other vegetables, which is why they are often categorized as such. Cooking tempers the acid and bitter qualities in tomatoes and brings out their warm, rich, sweetness.
Although tomatoes are closely associated with Italian cuisine, they are actually originally native to the western side of South America, including the Galapagos Islands. The first type of tomato grown is thought to have more resembled the smaller-sized cherry tomato than the larger varieties.
The tomato was not cultivated in South America, but rather in Mexico, supposedly because the Mexican Indians were intrigued by this fruit since it resembled the tomatillo which was a staple in their cuisine. The Spanish conquistadors who came to Mexico shortly after Columbus's discovery of the New World "discovered" tomatoes and brought the seeds back to Spain, beginning the introduction of the tomato into Europe.
Although the use of tomatoes spread throughout Europe and made its way to Italy by the 16th century, it was originally not a very popular food since many people held the belief that it was poisonous since it was a member of the deadly Nightshade family. They were wise but not fully accurate, as the leaves of the tomato plant, but not its fruits, do contain toxic alkaloids. Yet, due to this belief, tomatoes were more often grown as an ornamental garden plant than as a food for many more centuries in several European countries.
Tomatoes made their way to North America with the colonists who first settled in Virginia, yet did not readily gain popularity until the late 19th century. Since new varieties have been developed and more efficient means of transportation established, tomatoes have become one of the top selling vegetables in this country. Today, the United States, Russia, Italy, Spain, China and Turkey are among the top selling commercial producers of tomatoes.
Choose tomatoes that have a deep rich color. Not only is this one of the signs of a delicious tasting tomato, but the deep color also indicates that it has a greater supply of the health-promoting phytonutrient red pigment, lycopene. Tomatoes should be well shaped and smooth skinned with no wrinkles, cracks, bruises or soft spots. They should not have a puffy appearance since this indicates that they will be of inferior flavor and will cause excess waste during preparation. Ripe tomatoes will yield to slight pressure and will have a noticeably sweet fragrance.
When buying canned tomatoes, it is often better to buy those that are produced in the United States as many foreign countries do not have as strict standards for lead content in containers. This is especially important with a fruit such as tomatoes, whose high acid content can cause corrosion to, and subsequent migration into the foods of the metals with which it is in contact.
Since tomatoes are sensitive to cold, and it will impede their ripening process, store them at room temperature and out of direct exposure to sunlight. They will keep for up to a week, depending upon how ripe they are when purchased. To hasten the ripening process, place them in a paper bag with a banana or apple since the ethylene gas that these fruits emit will increase the tomato's maturation. If the tomatoes begin to become overripe, but you are not yet ready to eat them, place them in the refrigerator (if possible, in the butter compartment which is a warmer area), where they will keep for one or two more days. Removing them from the refrigerator about 30 minutes before using will help them to regain their maximum flavor and juiciness. Whole tomatoes, chopped tomatoes and tomato sauce freeze well for future use in cooked dishes. Sundried tomatoes should be stored in an airtight container, with or without olive oil, in a cool dry place.
When Buying Ketchup, Choose Organic
Organic ketchup contains 3 times as much lycopene as non-organic brands.
Lycopene, a carotenoid shown to help protect against breast, pancreatic, prostate and intestinal cancer, and to reduce the heart attack risk (see Health Benefits above), is present in much higher amounts in organic compared to non-organic brands of ketchup.
Researchers Betty Ishida and Mary Chapman at the U.S. Agricultural Research Service in Albany, CA, tested lycopene levels and antioxidant activity in 13 brands of ketchup: 6 popular ones, 3 organic, 2 store brands, and 2 from fast food chains. While purple and green ketchups had a similar lycopene content to their red counterparts, organic ketchups excelled, with one brand containing 183 micrograms of lycopene per gram of ketchup, about 5 times as much per weight as a tomato. Non-organic brands averaged 100 micrograms per gram, with one fast-food sample containing just 60 micrograms per gram. If you want high lycopene levels, pick the darkest red organic ketchup. And don't forget to enjoy your ketchup in a meal that also provides a little fat. Lycopene, like other carotenoids, is fat-soluble, which means it is not well absorbed without fat.
For some of our favorite recipes, click Recipes.
Tips for Preparing Tomatoes:
Before serving, wash tomatoes under cool running water and pat dry.
If your recipe requires seeded tomatoes, cut the fruit in half horizontally and gently squeeze out the seeds and the juice.
It is especially important when cooking tomatoes to not use aluminum cookware since their high acid content will interact with the metal. This may result in the migration of the aluminum into the food, which will not only impart an unpleasant taste, but more importantly, may have deleterious effects on your health.
For the Most Lycopene, Use the Whole Tomato
It's well known that a high intake of tomato products is associated with lowered risk of colon and prostate cancers, a beneficial effect thought to be due to tomatoes' high content of the carotenoids, lycopene and beta-carotene.
Tomato products, such as tomato paste, have been recommended over whole fresh tomatoes because they concentrate tomatoes and thus deliver more of their protective carotenoids, despite the fact that tomato peels are usually eliminated during processing.
A study published in the Journal of Nutrition, however, once again confirms that Mother Nature knows best: consuming whole, natural foods-in this case, the whole tomato-is best.
When tomato paste that included tomato peels was compared to classically made (without peels) tomato paste, carotenoids were significantly better absorbed in the whole tomato paste. Study participants absorbed 75% more lycopene and 41% more beta-carotene from whole tomato paste compared to conventionally made (without peels) tomato paste. The take home message: look for products that contain whole tomatoes, including their peels, or make your own whole tomato paste. Not only is it quick, easy and inexpensive, but the improvement in flavor will amaze you. Once you've enjoyed its heavenly aroma while cooking and tasted your own freshly made, whole tomato paste, you'll only resort to store-bought tomato paste in emergencies.
A Few Quick Serving Ideas:
To make your own tomato paste, simply healthy sauté a couple of cloves of chopped garlic and/or 1-2 large chopped onions a couple of minutes until translucent, then add 8-10 chopped whole tomatoes, a teaspoon of dried or several teaspoons of fresh chopped oregano, basil, and any other herbs you enjoy, such as parsley or rosemary, and simmer for 30-45 minutes. Remove from the heat, drizzle with olive oil, and add sea salt and freshly ground black pepper to taste. For a fancier version, sauté chopped olives and/or mushrooms along with the garlic and onions.
Tomatoes are a great addition to bean and vegetable soups.
Enjoy a classic Italian salad-sliced onions, tomatoes and mozzarella cheese drizzled with olive oil.
Combine chopped onions, tomatoes, and chili peppers for an easy to make salsa dip.
Purée tomatoes, cucumbers, bell peppers and scallions together in a food processor and season with herbs and spices of your choice to make the refreshing cold soup, gazpacho.
Add tomato slices to sandwiches and salads. To keep things colorful, use yellow, green and purple tomatoes in addition to red ones.
Allergic Reactions to Tomatoes
Although allergic reactions can occur to virtually any food, research studies on food allergy consistently report more problems with some foods than with others. It turns out that tomatoes are one of the foods most commonly associated with allergic reactions. Other foods commonly associated with allergic reactions include: cow's milk, wheat, soy, shrimp, oranges, eggs, chicken, strawberries, spinach, peanuts, pork, corn and beef. These foods do not need to be eaten in their pure, isolated form in order to trigger an adverse reaction. For example, yogurt made from cow's milk is also a common allergenic food, even though the cow's milk has been processed and fermented in order to make the yogurt. Ice cream made from cow's milk would be an equally good example.
Some of the most common symptoms for food allergies include eczema, hives, skin rash, headache, runny nose, itchy eyes, wheezing, gastrointestinal disturbances, depression, hyperactivity and insomnia. Individuals who suspect food allergy to be an underlying factor in their health problems may want to avoid commonly allergenic foods.
Tomatoes Belong to the Nightshade Family
Tomatoes are one of the vegetables in the nightshade (Solanaceae) family, which includes eggplant, bell peppers, and white potatoes. Anecdotal case histories link improvement in arthritis symptoms with removal of these foods; however, no case-controlled scientific studies confirm these observations. For more on nightshades, please see our article "What are nightshades and in which foods are they found?"Tomatoes are an excellent source of vitamin C, vitamin A, and vitamin K. They are also a very good source of molybdenum, potassium, manganese, dietary fiber, chromium, and vitamin B1. In addition, tomatoes are a good source of vitamin B6, folate, copper, niacin, vitamin B2, magnesium, iron, pantothenic acid, phosphorous, vitamin E and protein.
For an in-depth nutritional profile click here: Tomato.
In-Depth Nutritional Profile
In addition to the nutrients highlighted in our ratings chart, an in-depth nutritional profile for Tomatoes 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.
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