In the past several years, critics have sniped at beta-carotene, but the evidence still overwhelmingly supports its usefulness.

Recent studies found that beta-carotene enhances the ability of immune cells to detect and fight viruses and cancer cells. Other research reports that it might lower the risk of rheumatoid arthritis and prostate cancer.

Meanwhile, research shows that other carotenoids are also important for health. Evidence is building that one of them, lutein, may prevent macular degeneration, which can result in blindness. Lutein might also help prevent some forms of cancer.

Similarly, lycopene, found in tomatoes, may play a major role in reducing the risk of prostate cancer in men and breast cancer in women.

Although some experts believe lutein and lycopene are the emerging nutritional stars, research suggests that a combination of carotenoids may be best. Such a mix of carotenoids most closely approximates what's found in fruits and vegetables.

Other studies point out the interactivity of beta-carotene, lutein, lycopene and other antioxidants such as vitamins C and E. The bottom line: They seem to work best as a team. It's worth keeping in mind when you select your foods--or supplements.