PL9 - EXTRASKELETAL EFFECTS OF VITAMIN D

Osteoporos Int (2010) 21:Suppl1S1–S6 May 2010
B. Dawson-Hughes 1,*; 1USDA Human Nutrition Research Center on Aging, Tufts University, Boston, United States
From IOF World Congress on Osteoporosis & 10th European Congress on Clinical and Economic Aspects of Osteoporosis and Osteoarthritis – Plenary Lectures Abstracts

Abstract
In addition to its classical effects on bone and muscle, vitamin D has been associated with a number of chronic diseases, including diabetes, cancer, cardiovascular disease, and infection. Mechanisms may involve effects of vitamin D and its metabolites on inflammation and on cell differentiation, proliferation, and apoptosis. Diabetes currently affects 285 million people worldwide at a cost of 11.6% of the total world health expenditure. Observational studies show a fairly consistent association between low vitamin D status and both prevalent and incident type two diabetes mellitus (t2DM). Evidence from post hoc analyses of vitamin D and/or calcium supplementation trials suggests that combined vitamin D and calcium supplementation may have a role in the prevention of t2DM, particularly in high-risk populations with glucose intolerance. In 2010, cancer will become the world’s leading cause of death. It has been estimated that one third of cancer deaths may be attributable to diet. Higher levels of 25OHD have been linked to lower rates of cancer of the colon, prostate, breast, and lung.

For prostate and breast cancer, there appears to be a U-shaped association, with cancer mortality declining as 25OHD levels approach 60 to 100 nmol/L and increasing as they exceed this range. In contrast, serum 25OHD may be positively associated with pancreatic cancer incidence rates, at least in male smokers.
Polymorphisms in the vitamin D receptor gene seem to affect cancer risk, particularly at low calcium intake levels. In the one available prospective calcium and vitamin D intervention trial, supplementation appeared to reduce the incidence of all cancers, but this finding needs to be confirmed in larger studies.
Finally, vitamin D insufficiency has been associated with several autoimmune diseases and infections, and with hypertension and cardiovascular disease. Highlights of the clinical evidence will be reviewed. In conclusion, evidence linking vitamin D insufficiency to chronic disease progression is based largely on association studies. These studies must be interpreted with caution because of their inability to account entirely for the impact of powerful known confounders. The true effect of vitamin D on chronic disease risk and progression will remain unknown until randomized, controlled clinical trials are performed.