The research mentioned thus far on beta-carotene suggest a lower risk of mortality stems from beta carotene intake from food sources but not beta-carotene supplements. The benefit may also come from other substances in the vegetable food source and not necessarily the beta carotene itself.
Vitamin D and heart disease:
Investigators followed a total of 1,194 men over a median duration of 12.7 years in this longitudinal study looking at the link between blood levels of vitamin D and mortality. They looked at vitamin D levels and cardiovascular-related as well as all cause mortality. There was a clear U-shaped curve when looking at the relationship between vitamin D levels and all-cause mortality along with cancer-related mortality, meaning the risk of mortality was significantly increased at both low and high blood levels of vitamin D. In this study, the range with the lowest mortality was about a vitamin D concentration of 24 to 34 ng/ml (60 to 85 nMol/L), which approximately translates 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 but no increase in cardiovascular mortality was seen. There was a sharp drop in cardiovascular related death rates as study participants went from being vitamin D deficient to approaching a level of 26 ng/ml. At this point there was a leveling off with no added benefit or increase in mortality seen with higher vitamin D levels. Men with low concentrations of vitamin D had a higher cardiovascular mortality. Overall mortality was increased by 50–60% among subjects in the lowest 10% and highest 5% of the vitamin D distribution, whereas cardiovascular mortality was increased only in the bottom 10%. The ideal vitamin D dose according to findings in this study is 2000 IU/d. (13)
Vitamin D is important for reducing the risk of heart disease. A report by the Institute of Medicine (IOM) and the Endocrine Society’s Clinical Practice Guidelines tripled the amount of vitamin D required for most children and adults. The Endocrine Society’s Clinical Guidelines for vitamin D concluded that vitamin D deficiency be defined as a 25(OH)D < 20 ng/ml, insufficiency as a 25(OH)D of 21–29 ng/ml and sufficiency as a 25(OH)D of 30–100 ng/ml. For preventing and treating vitamin D deficiency the Guidelines recommended vitamin D intake should be: children < 1 y 400-1,000 IU/d, children 1-18 y 600-1,000 IU/d and adults 1,500-2,000 IU/d to maintain 25(OH)D concentrations of 40–60 ng/ml. Upper limits of vitamin D intake were also set as follows: 2000 IU/day for children up to age 1 year; 4000 IU/day for children aged 1 – 18 years, and up to 10,000 IU/day for adults aged 19 years and older. The IOM report concluded that dietary and supplemental vitamin D intake is adequate to satisfy both children and adult, but their study suffered from serious flaws. A study (Moore et al) suggests that neither children nor adults in the US are obtaining the new RDA for vitamin D. Among women vitamin D intake from food was 156–208 IU/d and with supplements 244–324 IU/d. For men, corresponding values were 208–320 IU/d and 308–392 IU/d. There is no evidence that there is a downside to increasing vitamin D intake in children and adults, with the exception of those with chronic granuloma forming disorder or lymphoma in which high vitamin D levels may occur resulting in high calcium levels. (35)