Caution: Synthetic beta-carotene has been linked to increased risk of lung cancer in smokers. Until more is known, smokers should avoid all beta-carotene supplements.

Years ago, researchers theorized that beta-carotene in skin might help protect against sensitivity to ultraviolet light from the sun. Large amounts of beta-carotene (up to 300,000 IU per day for at least several months) have allowed people with photosensitivity to stay out in the sun several times longer than they otherwise could tolerate.^1,2,3 The protective effect appears to result from beta-carotene’s ability to protect against free-radical damage caused by sunlight.⁴

Adenosine monophosphate (AMP) is a substance made in the body that is also distributed as a supplement, although it is not widely available. According to one report, 90% of people with porphyria cutanea tarda responded well to 160 to 200 mg of AMP per day taken for at least one month.⁵ Complete alleviation of photosensitivity occurred in about half of the people who took AMP.

In a small preliminary trial, supplementation with fish oil (10 grams per day for three months) reduced photosensitivity in 90% of people suffering from polymorphous light eruptions.⁶

Niacinamide, a form of vitamin B3, can reduce the formation of a kynurenic acid—a substance that has been linked to photosensitivity. One trial studied the effects of niacinamide in people who had polymorphous light eruption.⁷ While taking one gram three times per day, most people remained free of problems, despite exposure to the sun. Because of the potential for adverse effects, people taking this much niacinamide should do so only under medical supervision.

Cases have been reported of people with photosensitivity who responded to vitamin B6 supplementation.^8,9 Amounts of vitamin B6 used to successfully reduce reactions to sunlight have varied considerably. Some doctors suggest a trial of 100 to 200 mg per day for three months. People wishing to take more than 200 mg of vitamin B6 per day should do so only under medical supervision.