Regular readers will know that I have a particular interest in the role of sunlight in health, in large part due to its ability to stimulate vitamin D production in the body. Vitamin D, in turn, has been found to be association with a very wide variety of disease processes including cancer, diabetes, and multiple sclerosis. Back in 2007, one of my blogs focused on the relationship between vitamin D levels and risk factors for cardiovascular disease (e.g. heart disease and stroke). This study found that individuals with relatively low levels of vitamin D were at significantly increased risk of a variety of risk factors including high blood pressure, diabetes, obesity and raised levels of blood fats known as triglycerides.
I was therefore interested to read of a study published this week, that has found a relationship between vitamin D levels and cardiovascular disease [1]. This study involved following 6219 Finnish men and women for an average of about 27 years. In those with the highest levels of vitamin D, risk of death from cardiovascular disease was found to be 24 per cent than in those with the lowest vitamin D levels.
Cardiovascular disease death encompasses deaths due to heart disease and stroke. The authors of this study went further by looking at the relationship between vitamin D levels and these specific causes of death. They found no significant relationship between vitamin D levels and risk of death due to heart attack. However, there was a striking relationship between vitamin D levels and risk of death due to stroke. individuals with the highest vitamin D levels were at a 52 per cent reduced risk of dying from stroke compared to those with the lowest levels.
Now ‘epidemiological’ studies of this nature can only be used to show associations between things, and it is not certain whether optimising vitamin D levels actually reduces the risk of stroke. Ideally, any truly protective role of vitamin D needs to be proven with intervention studies (which, say, assess cardiovascular disease risk in individuals treated with vitamin D or placebo). In the meantime, I continue to attempt to optimise my vitamin D levels. If vitamin D turns out to help prevent stroke, then this optimising my vitamin D levels may turn out to be a very worthwhile endeavour (there is a strong history of stroke in my family).
References:
1. Kilkkinen A, et al. Vitamin D status and the risk of cardiovascular disease death. Am J Epidemiol 2009;170(8):1032-9
