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The Tomato: A Multi-Talented Food
The late Southern writer and humorist, Lewis Grizzard, once said, "It's difficult to think anything but pleasant thoughts while eating a homegrown tomato." But the benefits of eating tomatoes extend far beyond just pleasant thoughts, according to a recent review article. They appear to offer protection from certain types of cancer, and emerging research suggests they could provide more protective mechanisms in the body than once thought.
Tomatoes are one of the few non-starchy vegetables that most people like in some form or fashion. Whether fresh or as a canned product, they are readily available, have an established record of acceptability among people of all ages (think pizza!) and cultures (think salsa!), and are available in a variety of convenient forms, i.e. fresh, canned, tomato sauce, tomato paste, salsa, pasta sauce.
The tomato is a unique package, nutritionally speaking. It is a good source of vitamins A, vitamin C, potassium, fiber, and the antioxidant lycopene. Lycopene is the phytochemical that gives the tomato its deep red color, and it is the principal bioactive component in the tomato. Its antioxidant potency is well-documented, and the relationship between lycopene and a lower risk of prostate cancer has been the subject of various research studies.
Researchers compiled and reviewed over 100 past studies on the vegetable (its USDA classification) that is botanically a fruit. Earlier studies focused on the presence of lycopene and its antioxidant activity that appears to protect against certain cancers. New research is exploring the possibility that tomatoes may protect against cardiovascular disease (CVD), osteoporosis, ultraviolet light-induced skin damage, and cognitive dysfunction.
Tomatoes' role in reducing the risk of CVD has grown because our understanding of the underlying causes of cardiovascular disease has expanded to include inflammation, endothelial dysfunction (problems with the lining of blood vessels), and oxidative damage. Eating more foods high in antioxidants, like tomatoes, helps reduce the effects of these factors.
Promising results have also been reported for the role of tomato products in skin protection, as well as bone and brain health. Studies found that people who ate tomato paste regularly were less likely to experience the ultraviolet light-induced skin rash known as erythema. Other studies found that women with osteoporosis and cognitively-impaired individuals tended to have lower serum lycopene levels when compared to control groups. These findings open up the possibility that the lycopene in tomato products may offer even more protective benefits than previously thought.
Fresh fruits and vegetables are usually considered nutritionally superior to processed foods, but the heat required for cooking and processing canned tomato products increases the bioavailability of lycopene by softening cell walls. Lycopene absorption is also greater in the presence of some type of fat or oil.
Tomatoes are also one of the top contributors of potassium in the diets of Americans. Most people do not consume enough potassium even though there is good evidence that it helps lower blood pressure and reduce the adverse effects of a high sodium intake. Potassium may also lower the risk of developing kidney stones, and protect against age-related bone loss.
While the exact mechanism by which tomatoes and other fruits and vegetables reduce the risk of disease is not fully understood, it is likely that various parts of the entire food package work together to contribute to the overall health benefit. No single component is responsible.
Americans do not consume the recommended 2½ cups of vegetables a day, and the researchers hope that by making the potential benefits of the tomato clear, people will make more effort to consume tomato products, increasing the likelihood that compliance with guidelines for vegetable consumption will improve.
The review is published in the March/April issue of the American Journal of Lifestyle Medicine.
March 22, 2011
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