Introduction

Foods like vegetable juice, tomato soup, spaghetti sauce, pink grapefruit, and watermelon have at least one characteristic in common--they are all sources of lycopene, one of the carotenoids, or plant pigments, that give these foods their characteristic hue. Researchers believe these substances may act as antioxidants in the body, protecting cells from oxygen-related damage that can result from normal cell functions. In this role, carotenoids like lycopene may help guard against the accumulating cell damage that can lead to heart disease and some kinds of cancers. In a recent article published in the Journal of the American College of Nutrition, researchers focused specifically on the disease-fighting potential of lycopene.

What is the evidence?

Much of the scientific literature that addresses the health benefits of lycopene is focused on its apparent ability to protect against prostate, lung, and stomach cancer. Test tube studies have shown that lycopene slows the growth of cancer cells, and other studies suggest that it may delay the growth of tumors in laboratory mice. The evidence in humans comes mainly from epidemiologic studies, where scientists assess the food habits of large groups of people in an attempt to find a link between diet and disease. In several such studies, people who consumed the most lycopene-rich foods, commonly tomato products like spaghetti sauce, had a reduced risk of cancer.

Scientists have also explored the possible role of lycopene in cardiovascular disease prevention, but here the pool of evidence is much smaller. As an antioxidant it may help to reduce damage caused by "bad" LDL cholesterol.

It is difficult to compare the results of these studies, because while some measured the levels of lycopene in blood samples, others determined lycopene status by measuring the intake of lycopene-rich foods. Some of the dietary studies looked only at intake of tomatoes and tomato products, as the foods that represent the largest dietary source of lycopene in the diets of study participants.

While scientists continue to study how this plant substance may help to prevent disease, they do not yet have enough evidence to warrant a recommended daily intake of lycopene. Ultimately, though, this is one instance where it really isn't necessary to wait for the scientific verdict to be in, since eating foods rich in lycopene fits easily into other well-established dietary guidelines, such as the advice to consume multiple servings of fruits and vegetables each day. Nutritionists have known for a long time that when it comes to picking produce, color is a good guide, with the brighter the better a good rule of thumb. In the case of lycopene, frequent bouts of "seeing red" - on your plate that is - might prove helpful.

Interestingly, heat makes the lycopene in tomatoes more available for absorption. Thus, cooked products like tomato or spaghetti sauce, canned tomatoes, or juice contain more "free" lycopene than do fresh tomatoes.