Lung Cancer

It is important to note that taking beta carotene in oral supplement form is advised against. One study, the Beta-Carotene and Retinol Efficacy Trial (CARET), was stopped early because it showed that beta-carotene/vitamin A takers who were heavy smokers, ex-smokers or asbestos workers were showing a 28% increased risk of lung cancer in smokers (versus placebo) and a 17% more likely chance of dying, mostly of lung cancer or heart disease. (5)

Vitamin D and Cancer

Regarding the intake of vitamin D, the range of vitamin D intake with the lowest mortality was a vitamin D concentration of 24 to 34 ng/ml (60 to 85 nMol/L), which approximately translated to a vitamin D dose of 2000 IU/d. In general, the biggest drop in overall death rates were seen when subjects went from being vitamin D deficient to reaching adequate levels. However, too much vitamin D translated into a gradual increase of mortality rate with cancer deaths rising significantly for the highest levels of vitamin D intake. The ideal vitamin D dose according to findings in this study is 2000 IU per day for adults. (7)