The long-running Harvard University cohort studies, the US Nurses Health Study, Health Professionals Study and Physician Health study, have studied in great detail the health outcomes of these professional groups related to various risk factors.
This review, published in Molecular Food and Nutrition Research has revealed the great importance of vitamin D supplementation.
While the methodologies and statistics used in the each of the studies reviewed from this cohort varied, the message was strong and clear.
The risk of various cancers was reduced with vitamin D supplementation or maintenance of adequate vitamin D levels; for pancreatic cancer by 41%, breast cancer 28% and bowel cancer 33%. For MS there was a 65% reduction in risk, for hip fractures 37% and for heart attacks, there was a 2.1% reduction in risk for every 2.5nmol/L increase in vitamin D level in the blood.
The authors concluded that, based on the findings from the Harvard cohorts, as well as many other studies, the risk of various chronic disease endpoints is minimised at a circulating vitamin D level of at least 30 ng/mL (75nmol/L). We recommend for people who actually have one of these disease, maintaining the level at 150nmol/L at least provides the best chance of a good outcome.