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Milk and cereal grains are often fortified with vitamin D.
found in a another study of vitamin D intake in 2007 the Canadian Cancer Society, (a national community-based organization of volunteers) recommended that all adults begin taking 1,000 IU per day (five times more than the government says they need) . A US National Cancer Institute study analyzed data from the third national Health and Nutrition Examination Survey to examine the relationship between levels of circulating vitamin D in the blood and cancer mortality in a group of 16,818 participants aged 17 and older. It found no support for an association between 25(OH)D and total cancer mortality. However, the study did find that "[c]olorectal cancer mortality was inversely related to serum 25(OH)D level, with levels 80 nmol/L or higher associated with a 72% risk reduction (95% confidence interval = 32% to 89%) compared with lower than 50 nmol/L, Ptrend = .02." Unlike other studies, this one was carried out prospectively — meaning that participants were followed looking forward — and the researchers used actual blood tests to measure the amount of vitamin D in blood, rather than trying to infer vitamin D levels from potentially inaccurate predictive models. A report from the National Health and Nutrition Examination Survey (NHANES) involving nearly 5,000 participants found that low levels of vitamin D were associated with an increased risk of peripheral artery disease (PAD). The incidence of PAD was 80% higher in participants with the lowest vitamin D levels
Cardiovascular disease
(<17.8 ng/mL). Cholesterol levels were found to be reduced in gardeners in the UK during the summer months. Low levels of vitamin D are associated with an increase in high blood pressure and cardiovascular risk. Numerous observational studies show this link, but of two systemic reviews one found only weak evidence of benefit from supplements and the other found no evidence of a beneficial effect whatsoever. There is a certain amount of evidence to suggest that dietary vitamin D may be carried by lipoprotein particles into cells of the artery wall and atherosclerotic plaque, where it may be converted to active form by monocyte-macrophages. These findings raise questions regarding the effects of vitamin D intake on atherosclerotic calcification and cardiovascular risk. Calcifediol (25-hydroxy-vitamin D) is implicated in the