Lycopene , an antioxidant related to beta-carotene and found in tomatoes, helps reduce the symptoms of asthma caused by exercising. In one double-blind trial,¹ over half of people with exercise-induced asthma had significantly fewer asthma symptoms after taking capsules containing 30 mg of lycopene per day for one week compared to when they took a placebo.

In a preliminary trial, 26 men with prostate cancer were randomly assigned to receive lycopene (15 mg twice a day) or no lycopene for three weeks before undergoing prostate surgery. Prostate tissue was then obtained during surgery and examined. Compared with the unsupplemented men, those receiving lycopene were found to have significantly less aggressive growth of cancer cells.² In addition, a case report has been published of a 62-year-old man with advanced prostate cancer who experienced a regression of his tumor after starting 10 mg of lycopene per day and 300 mg of saw palmetto three times per day. As saw palmetto has not been previously associated with improvements in prostate cancer, the authors of the report attributed the response to the lycopene.³ In a preliminary trial, supplementation with 4 mg of lycopene twice a day for one year reduced the incidence of prostate cancer in men with precancerous changes in their prostate glands.⁴ Long-term controlled studies are needed to confirm these promising initial reports.

Antioxidants may protect the skin from sunburn due to free radical –producing ultraviolet rays.⁵ Combinations of 1,000 to 2,000 IU per day of vitamin E and 2,000 to 3,000 mg per day of vitamin C , but neither given alone, have a significant protective effect against ultraviolet rays, according to double-blind studies.^{6 , 7 , 8}

Oral synthetic beta-carotene alone was not found to provide effective protection when given in amounts of 15 mg per day or for only a few weeks’ time in larger amounts of 60 to 90 mg per day, but it has been effective either in very large (180 mg per day) amounts or in smaller amounts (30 mg per day) in combination with topical sunscreen.^{9 , 10 , 11 , 12 , 13}

Natural sources of beta-carotene or other carotenoids have been more consistently shown to protect against sunburn. One controlled study found that taking a supplement of natural carotenoids (almost all of which was beta-carotene) in daily amounts of 30 mg, 60 mg, and 90 mg gave progressively more protection against ultraviolet rays.¹⁴ In another controlled study, either 24 mg per day of natural beta-carotene or 24 mg per day of a carotenoid combination of equal amounts beta-carotene, lutein , and lycopene helped protect skin from ultraviolet rays.¹⁵ A preliminary study compared synthetic lycopene (10.1 mg per day), a natural tomato extract containing 9.8 mg of lycopene per day plus additional amounts of other carotenoids, and a solubilized tomato drink (designed to increase lycopene absorption) containing 8.2 mg of lycopene plus additional amounts of other carotenoids. After 12 weeks, only the two tomato-based products were shown to give significant protection against burning by ultraviolet light.¹⁶

It should be noted that while oral protection from sunburn has been demonstrated with several types of antioxidants , the degree of protection (typically less than an SPF of 2) is much less than that provided by currently available topical sunscreens. On the other hand, these modest effects will provide some added protection to skin areas where sunscreen is also used and will give a small amount of protection to sun-exposed areas where sunscreen is not applied. However, oral protection from sunburn is not instantaneous; maximum effects are not reached until these antioxidants have been used for about eight to ten weeks.^{17 , 18}

The carotenoid, lycopene , has been found to be low in the blood of people with atherosclerosis, particularly if they are smokers.¹⁹ Although no association between atherosclerosis and blood level of any other carotenoid (e.g., beta-carotene ) was found, the results of this study suggested a protective role for lycopene. Lycopene is present in high amounts in tomatoes.