When it comes to nutrients, one would think the fresher the source, the better. Tomatoes must be the exception that proves the rule. While health studies continue to demonstrate the myriad benefits of lycopene, a phytochemical abundant in tomatoes, nutritional studies present a twist: You get more lycopene from a processed or cooked tomato than you do from a fresh one.
That's because lycopene is tightly bound within a tomato's cell walls; heat, however, breaks down those walls, thus releasing more lycopene for absorption and use by the body. (In other words, cooking or processing increases lycopene's "bioavailability.") So, for instance, canned tomatoes, jarred salsa, ketchup, spaghetti sauce, tomato paste, and tomato soup are all good sources of lycopene, as are sauteed fresh tomatoes. And because it's fat-soluble, lycopene also becomes more available for absorption and use in the presence of dietary fats (like cheese or olive oil), which help dissolve and carry it into the bloodstream.
Why is more lycopene a good thing? Many of its health benefits are believed to derive from its powerful antioxidant properties. Lycopene's ability to counter oxidative stress is thought to be largely responsible for its role in fighting cancer and heart disease. In a landmark study, Harvard University researchers discovered that men who consumed 10 servings of tomato products a week reduced their risk of prostate cancer by as much as 45 percent. Research also suggests that lycopene can reduce the threat of other cancers, such as those of the colon, stomach, cervix, skin, and breast, as well as help to prevent atherosclerosis and heart disease by lowering LDL levels ("bad" cholesterol). Some observational evidence indicates that lycopene may reduce the risk of macular degenerative diseases as well.
Because the body does not produce lycopene, you can only obtain its benefits by eating foods that are rich in it. Hint: Lycopene is a carotenoid -- a plant pigment -- that gives certain fruits and vegetables a red hue, including pink grapefruit, watermelon, and guava. The riper and redder the tomato, generally speaking, the more lycopene it contains.
For most of culinary history, the tomato's health benefits were lost on humans. That's because the tomato is a member of the nightshade family, some of which are deadly, so many people assumed it was poisonous. (They were on to something: a tomato's leaves and stems are toxic.) It's only in the last 200 years that people have believed it safe to eat. One of the great characters in the history of the tomato was its advocate Colonel Robert Gibbon Johnson of Salem, New Jersey, who, legend has it, shocked his hometown in 1820 by safely consuming a basketful of tomatoes in front of a crowd of spectators. According to earlier chapters in the tomato's history, it grew in Montezuma's famous garden and was brought back to Renaissance Spain by the conquistador Hernando Cortez in the 16th century.