In 1981, Professor Robert Scragg first hypothesized that vitamin D deficiency contributed to heart disease. He used latitudinal, seasonal and altitudinal data to support his theory. Thirty-two years later, we are getting closer to understanding the truth of his theory.
Recently, Dr Peter Brondum-Jacobsen and colleagues from the Copenhagen University Hospital in Denmark studied more than 10,000 men and women, pooling from people that had a vitamin D level drawn in the early 1980s and following the patients for 29 years to see who developed heart disease, a heart attack or died. The average vitamin D level of these patients was 19 ng/ml.
Brøndum-Jacobsen P, Benn M, Jensen GB, Nordestgaard BG. 25-Hydroxyvitamin D Levels and Risk of Ischemic Heart Disease, Myocardial Infarction, and Early Death: Population-Based Study and Meta-Analyses of 18 and 17 Studies. Arterioscler Thromb Vasc Biol. 2012 Aug 30.
The authors found that patients with the lowest vitamin D levels had a 72% increased risk for heart disease, a 99% increased risk of heart attack, and 88% increased risk of early death, and a 122% increased risk for fatal heart attack, compared to those with higher levels. After correcting for confounders, some of which obscured the strength of the corrected results, such as obesity and age, the results remained strong.
Then they did a metanalysis of 18 general population studies that included more than 82,000 people. The studies used various definitions of inadequacy. They found the risk of early death with “inadequate levels” was 46%. In this metanalysis, the highest levels were associated with the lowest risk with no U shaped curve. Furthermore, they found that countries that fortified food with vitamin D were not exempt from these deaths. That is, food fortification was too low to prevent the early deaths.
Remember, this was likely mostly sun-derived vitamin D. It remains an open question if vitamin D supplements will achieve the same effect, although the basic science of how vitamin D works in the cardiovascular system make it likely that supplementation studies (using an adequate dose) will be positive. Keep your 25(OH)D level at about 50 ng/ml and remember that the sun is your friend.