Low Vitamin D Levels and Higher MI Risk

Deaths from cardiovascular disease are more frequent at higher latitudes, increase during the winter months, and are more common at higher altitude. And lower blood levels of vitamin D occur with the same distribution. It’s not surprising, therefore, that a search has been made for an association between vitamin D levels and the frequency of heart attacks. Such a study has just been reported in the Archives of Internal Medicine.

Harvard researchers measured plasma 25-hydroxyvitamin D levels in over 18,000 healthy men aged 40 to 75. After 10 years, 454 of them had had a heart attack - fatal or non-fatal. These men were matched with records and blood samples from 900 men form the collective who were alive and free of any cardiovascular disease or symptoms.
Men who had deficient vitamin D levels (15 nanog/mL or less) were at significantly higher risk for having a heart attack, compared with men whose levels were at least 30 nanog/mL. Their relative risk, or likelihood of having a heart attack, was 2.4 times that of men with normal vitamin D levels. This finding remained significant - the relative risk was 2.09 - after adjustment for different cardiovascular risk factors and lipid levels were made.
How does vitamin D affect cardiovascular risk? Possible reasons include the vitamin’s effects on blood vessel muscle cell growth, blood vessel calcification, higher risk of inflammatory changes, or a blood pressure effect.

If, in fact, vitamin D deficiency proves to be a cause of some heart attacks, the amount of vitamin required to avoid this may be higher than the current recommendations, 200 – 600 IU daily. Thus to increase circulating levels of vitamin D from 12 nanog/mL to35.5 nanog/mL would require roughly 3,000 IU daily. Sunlight is obviously an important source –a glass of milk will only supply about 100 IU.