Vitamin D Reduces Heart Attack Risk
Low levels of vitamin D in men are associated with a higher risk of a heart attack, according to a new study in the Archives of Internal Medicine.(1) Men with lower blood levels of vitamin D (15 nanograms per millileter of blood or less) had double the risk of a heart attack than men who had sufficient levels (30 nanograms or more). Blood levels of 50 to 60 nanograms are probably optimal for adults.
The best dietary sources are oily fish such as salmon, mackerel, and sardines, and fortified milk. Vitamin D is also produced in the skin when exposed to UVB ultraviolet light from sunlight. The use of sunscreen inhibits most vitamin D production. Geographic latitude, season, smog, and melanin levels all affect UVB exposure and vitamin D production.
Other recent research has shown that low levels of vitamin D are more common than previously thought and also that low vitamin D levels increase the risk of diabetes, osteoporosis, breast cancer, and autoimmune diseases. The conclusion that many researchers have come to is that the RDA of 200 to 400 IU intake of vitamin D is significantly too low and the recommended daily intake should probably should be between 1000 and 4000 IU per day, depending upon age and level of sun exposure. The exact long term safe dose of vitamin D is not entirely known, but dosages up to 10,000 IU per day in healthy adults are believed to be safe and all known cases of vitamin D toxicity have involved dosage of at least 40,000 IU per day.
1. Giovanucci D, Liu Y, Hollis BW, et. al,. 25-Hydroxyvitamin D and risk of myocardial infarction in men. Archives of Internal Medicine. 2008; 168: 1174-80.