Tomatoes, Lycopersicon esculentum, are a member of the nightshade family, a diverse group of over 2,800 species of plants which also includes potatoes, sweet and hot peppers, eggplant, tobacco and morning glory, to name a few. For a long time, tomatoes were not eaten due to the fear that they were poisonous like some other members of this plant family. Plants in this family contain a substance from the alkaloid family, which can affect muscle activity at the nerve level and digestive functions. The level of alkaloids in nightshade foods is low compared to other nightshade plants and health problems may only occur in individuals sensitive to this compound. Alkaloids are used in pharmaceutical compounds for a broad spectrum of medical issues such as pain control, chemotherapy and malaria treatment.
Fortunately, the tomato was found not to be poisonous, and even better, loaded with numerous health benefits, including prevention of many cancers, heart disease, diabetes, aging, osteoporosis and migraines. Its culinary uses have been known for a relatively short time, staring in the 1800’s.
Botanically, the tomato is a fruit, more precisely a berry. The tomato is native to western South and Central America, and may be localized to the Galapagos Islands, where the first tomatoes may have been small, yellow fruits resembling cherry tomatoes. The Aztecs began cultivating tomatoes around 700 AD, and they were discovered by the Spanish explorers in the 1500’s who spread them throughout the world and Europe, starting in Italy. Colonel Robert Gibbon Johnson of Salem, New Jersey is given credit for proving to the US that tomatoes could safely be eaten by consuming an entire basket of tomatoes on the court house steps, without incident, in front of a shocked crowd in the early 1800’s after bringing tomatoes home from a trip abroad. Our love affair with tomatoes started soon after this event. Tomatoes were initially imported prior to being grown in this country. A dispute over import tariffs in 1893 lead the Supreme Court to classify the tomato as a vegetable for taxation purposes only, and to this date, the tomato is still thought of as a vegetable.
Tomatoes are cultivated world-wide but China produces the largest amount, accounting for one-fourth of the global output, followed by the US, Turkey and India. They are available year-round but peak season is July – September.
Tomatoes are one of the most common home garden items. They are grown in the spring and summer in most regions of the US, but more commonly grown in fall and winter in Florida. Plants are commonly classified as determinate (bush type, bearing a full crop all at once and good for containers) or indeterminate (vining, continuous production until frost, includes most heirloom varieties). In the wild state, tomatoes require cross-pollination, but cultivation has lead to self-fertility traits.
In commercial production of tomatoes, they are usually picked unripe and stored in ethylene, a hydrocarbon gas which causes ripening. Tomatoes ripened in this way store longer but have poorer flavor and mealy quality to the flesh, compared to tomatoes ripened on the vine.
In February 1997, researchers from UC Davis School of Medicine and Harvard School of Public Health, presented their findings on the health benefits of lycopene, a phytonutrient found in tomatoes. Lycopene is a powerful antioxidant which has shown big benefits in regards to prevention of many cancers (prostate, lung, colon, pancreatic and breast), heart disease and aging (via UV protection). Unlike many other phytonutrients, lycopene has been studied extensively on humans as opposed to animals. The studies made note of the fact that tomatoes and tomato products needed to be cooked in order to achieve the most benefit from lycopene. Studies also demonstrated how cooking tomatoes in oil increased the body’s ability to absorb more nutrients from tomatoes. This information has lead many researchers to study how lycopene and other nutrients in tomatoes reduce major health problems. What was ultimately clear, and what is known about many nutrients, is that the whole food, in this case tomatoes, needs to be consumed, including the skin, in order to get the full health benefits. According to several studies by Dr. Steven Clinton of Ohio State University, simply taking a lycopene supplement does not provide the same cancer protection as eating the whole food.
An added health benefit for fighting prostate cancer has been found when tomatoes are eaten with broccoli. Broccoli is also well recognized for its anti-cancer antioxidant properties. These anti-cancer compounds form in broccoli after it is cut. If broccoli is cooked too quickly after being cut, the enzymes needed to form these compounds are destroyed, so allow cut broccoli to sit for about 10-15 minutes prior to exposing it to heat. A study published in Cancer Research showed a significant reduction in prostate cancer tumor size with a diet heavy in a combination of tomatoes and broccoli. According to one of the study researchers, Kirstie Canene-Adams, to equal the diet combination in the study, a 55 year old man would need to consume 1 ½ cups raw broccoli and 2 ½ cups of fresh tomato, 1 cup of tomato sauce or ½ cup of tomato paste daily.
Another tomato combination is found with green tea for prostate cancer prevention. A study published in 2007 in the Asia Pacific Journal of Clinical Nutrition showed an 82% reduction in prostate cancer risk with a diet rich in both ingredients.
And last but not least, for the most lycopene out of your tomato, choose organic for fresh and prepared foods like ketchup and tomato paste. A study conducted by the USDA Agricultural Research Service in Albany, California, found that the organic tomatoes delivered 3 times as much lycopene as non-organic.
Lycopene is not the only compound in tomatoes that imparts major health benefits. Tomatoes are a significant source of Vitamins A, C and K, along with many minerals, including potassium and calcium, and fiber. One medium tomato has the same fiber as a slice of whole wheat bread with only 35 calories.
One cup of fresh tomato provides 57% of your total daily need for Vitamin C, 22% of Vitamin A, and 18% of Vitamin K, along with good amounts of 8 minerals, fiber, B Vitamins and protein.
Tomatoes are cold sensitive and should be ripened at room temperature. They will keep for about a week depending on level or ripeness. Avoid storing tomatoes in the refrigerator as this will greatly alter their taste. If you find yourself with a surplus of ripe tomatoes, they can be cooked and made into sauce or paste which cans and freezes well. Making your own ketchup is also an easy project.
Leaves of the tomato plant are considered poisonous and should not be eaten by humans or animals. While green tomatoes are wonderful cooked, they should not be eaten in large amounts raw. They contain tomatine, an alkaloid toxin, that may cause health issues.