Lycopene is part of the carotene family of nutrients, but unlike alpha-carotene or beta-carotene, lycopene cannot be converted into vitamin A. Lycopene, however, is a strong antioxidant and gives the red color to tomatoes, watermelon, guava and pink grapefruit.

Lycopene consumption has been linked to lower levels of cancer, particularly prostate cancer. Several studies have found that men with high intakes of lycopene were less likely to develop prostate cancer and had a lower risk of more aggressive prostate cancer. The same risk reduction was shown with consumption of tomatoes, which account for 80 percent of the lycopene in a typical American diet. But other studies showed only a minimal effect, if any, calling into questions whether it was lycopene that was reducing the risk, other compounds in tomatoes, or even simply a diet rich in fruits and vegetables. A recent study suggests a gene variation may predict who will benefit from the cancer-fighting properties of lycopene.

Studies testing lycopene to treat prostate cancer have also shown minimal results, and lycopene can interfere with radiation and chemotherapy if taken during cancer treatment.

The nutrient is more easily absorbed from cooked foods and when consumed with a little bit of fat, at least three to five grams. A very high intake of lycopene can result in a deep orange discoloration of the skin but appears to have no other risks. There is no established daily recommendation for lycopene.

— Markian Hawryluk, The Bulletin

Good sources of lycopene:

Tomato (1 medium): 32 mg

Spaghetti sauce (1 cup): 33 mg

Tomato soup (1 cup): 13 mg

Watermelon (1 wedge): 13 mg

Ketchup (1 tablespoon): 2.5 mg

Pink grapefruit (½ fruit): 1.7 mg

Sources: Linus Pauling Institute, American Cancer Society