How much beta carotene do you need?

50 mg/day in 3 doses: Multivitamin formulas frequently provide 3-15 mg of beta carotene (5000-25000 units) when given 51 mg/day in 3 divided doses,serum concentration of beta carotene level was significantly high.Daily doses up to 300mg have been used to treat photosensitivity disorders.In double blind studies beta carotene supplementation increased lung cancer in smokers- 18-28 %.Some humans can't convert to Vit A