Ask Tufts Experts

I am taking a vision-essentials supplement that contains 15,000 international units (IU) per day of beta-carotene. Is this too much and is it dangerous?

According to Robert Russell, MD, director of the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, there is evidence in two epidemiologic intervention studies that high dose beta-carotene supplements (approximately 50,000 IU of beta-carotene per day) can cause increased lung cancer among smokers. But there is no evidence in humans, he says, that there is a risk of taking beta-carotene unless you are a smoker. Dr. Russell adds, “I would not be concerned about taking 15,000 IU of beta-carotene (not 15,000 IU of vitamin A!), although I find it curious that it is in a supplement being marketed for visual health. Beta-carotene is not present in the eye. The carotenoid that may be beneficial to vision is lutein, which can be found in green leafy vegetables, such as spinach. I do not think beta-carotene in and of itself has anything to do with vision other than as a source of vitamin A.”