Lower Your Heart Attack Risk with Vitamin D
By: David A Fein, MD
Vitamin and nutritional supplements have become increasingly popular as strategies for feeling well and avoiding disease. Whether on the internet, radio and TV ads or in the popular media, numerous claims are made for the abilities of these supplements to keep us well. In fact, the evidence for most of these supplements is quite slim. Some vitamin supplements may actually even increase the risk of cancer or heart disease.
Vitamin D may be the exception. Vitamin D has long been recognized as important for maintaining bone health. Its primary role is to control the absorption of calcium from the diet. But it is also known to have a role in the control of blood pressure, inflammation and the immune system. Evidence continues to accumulate that Vitamin D deficiency is a risk factor for several serious diseases. And, Vitamin D deficiency is much more common than most of us realize.
A study published in the June 9, 2008, issue of Archives of Internal Medicine highlights the role of Vitamin D deficiency in the risk of heart attacks in men. Although the study only evaluated men, it is reasonable to assume that these results apply equally to women. The authors found that men who had normal Vitamin D levels, defined as 25 (OH) Vitamin D levels of at least 30 ng/ml, had approximately half the risk of heart attack compared to men with lower Vitamin D levels. Put the other way, having a low Vitamin D level doubles your chances of having a heart attack. When the data was analyzed to look at the risk of fatal hearts, rather than total heart attacks, the risk was even higher. Having a low Vitamin D level not only doubles your risk of a heart attack, it increases your risk of dying from a heart attack even more.
It is just as alarming to note that only 23% of the men in the study group had Vitamin D levels above 30 ng/ml. More than three quarters of the population in this study was Vitamin D deficient! The authors wrote that “this percentage is typical of many populations, and the prevalence of deficiency is even higher in subpopulations such as dark skinned individuals and elderly persons”. Vitamin D is produced by the skin upon exposure to sunlight. So in areas where sun exposure is high, Vitamin D levels often reach as high as 90 ng/ml. It is possible that levels that high might be associated with an even greater reduction in the risk of cardiovascular disease.
Vitamin D comes from both our diet and from sun exposure. Very few foods contain significant levels of Vitamin D. Current recommendations for daily Vitamin D intake are usually in the range of 200 to 600 units per day. However, these recommendations are based on maintaining a minimum blood level of only 20 ng/ml, well below the level at which increased cardiovascular risk was found in the Archives study.
Fish such as salmon, mackerel and tuna, along with fish liver oils are excellent sources of Vitamin D. A serving of fish may have 300 to 400 units of Vitamin D and a tablespoon of Cod Liver Oil has about 1300 units. Vitamin D is often added to certain foods such as dairy, yogurts, orange juice or cereal. These are usually labeled as “fortified with Vitamin D”. Even so, the usual dose of Vitamin D in a glass of milk is only about 100 units. So it would take more than a quart of milk per day just to maintain a minimal blood level of Vitamin –D.
Vitamin D can be synthesized in the skin with exposure to UV-B rays in sunlight. This is normally our major source of Vitamin D. In general, it takes about 10 30 minutes of exposure to midday sunlight to make the Vitamin D you need. Of course, this also affected by other factors such as latitude, cloud cover, clothing and wearing sunblock. UV-B does not penetrate glass. So exposure to sunlight inside your house or car will not result in Vitamin D production. Those who live in higher latitudes where sun exposure is weaker, or those who are rarely outdoors during daylight hours, may need even more exposure to maintain adequate levels. Those who live at latitudes above that of Boston can not get sufficient sunlight, regardless of time spent outside, to maintain normal Vitamin D levels from November through February. Only those living south of South Carolina are able to get adequate sun exposure throughout all 12 months of the year.
Since most of us do not get nearly enough sun exposure on a regular basis to maintain high levels of Vitamin D and our diets are often too low in Vitamin D, this is one nutritional supplement that appears to offer a potential benefit even in those who otherwise have healthy diets. Of course, overly aggressive supplementation of Vitamin D can be associated with serious side effects. Daily intake up to 3,000 10,000 units per day has been reported to rarely cause toxic effects. Long-term intake of doses beyond that range can cause intestinal symptoms and excessive calcium levels in the blood.
As the evidence mounts for the wide range of detrimental effects associated with low levels of Vitamin D we are increasingly recognizing that many of us are deficient in this important nutrient. Those who can not increase their daily sun exposure, or are concerned about the potential carcinogenic and aging effects of sun exposure on their skin, should consider adding a Vitamin D supplement to their daily regimen. Our recommendation is a daily dose of 800 units per day as a general preventive.