Why was beta carotene dropped from the PHS II trial?
We decided not to continue the beta-carotene component of the trial because the important scientific questions regarding the health effects of beta-carotene supplementation have been satisfactorily answered. Based on two decades worth of data contributed by PHS participants, beta carotene did not reduce the risk of total cardiovascular disease, total cancer, or total mortality. You will be reassured to learn that no serious adverse health effects of beta-carotene supplementation were observed in the PHS, even among men who took the vitamin for the longest periods of time.
