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.
Beta-carotene supplementation, even in very large amounts, is not known to cause any serious side effects,338, 339 however, excessive intake (more than 100,000 IU, or 60 mg per day) sometimes gives the skin a yellow-orange hue. People taking beta-carotene for long periods of time should also supplement with vitamin E, as beta-carotene may reduce vitamin E levels.340 Beta carotene supplementation may also decrease blood levels of lutein, another carotenoid.341
Preliminary studies in animals indicate that beta-carotene supplementation, when combined with heavy alcohol consumption, may enhance liver toxicity.342 Until more is known, alcoholics and persons who consume alcohol on a daily basis should avoid supplementing with beta-carotene.
One study showed a slightly increased risk of vascular surgery among people with intermittent claudication who took beta-carotene supplements.343 Until more is known, persons wishing to use beta-carotene supplements should first consult with their doctor.