Research appearing in the Archives of Internal Medicine (June, 2008; 9; 168(11):1174-80) looked at data from the Health Professionals Follow-up Study. Blood samples collected from men aged 40 to 75, taken between 1993 and 1995 were tested for 25-hydroxy vitamin D. During the following 10 years 454 men either had a non-fatal myocardial infarction or fatal heart disease. They were matched with the 900 subjects with similar age, smoking status, family history and other risk factors, who did not have heart disease. It was found that patients with plasma vitamin D levels lower than 15 ng/ml had a 2.4 fold increase in the risk for a heart attack when compared to subjects with serum vitamin D greater than 30 ng/ml.