Vitamin D—a Heart Healthy Nutrient
July 31, 2008—Low levels of vitamin D in the blood may increase risk of cardiovascular events such as a heart attack, according to two recent studies published in the Archives of Internal Medicine.
In addition to its critical role in bone development and maintenance, recent research has shown that vitamin D may be far more important for other aspects of health and disease prevention than was previously realized. In fact, research has linked low levels of vitamin D with chronic diseases such as cancer and multiple sclerosis. Now, new research suggests that inadequate vitamin D may increase the risk of heart attacks and death due to cardiovascular disease and other causes.
Investigating diet’s impact on heart health
In the Health Professionals Follow-up study, a study evaluating the associations between diet and the incidence of chronic disease, 18,225 men ages 40 to 75 were evaluated for their blood levels of vitamin D (measured as 25-hydroxyvitamin D [25(OH)D]) and subsequent risk of heart attack. After ten years of follow-up, 454 men had a heart attack or died from coronary artery disease. Men who had less than 15 nanograms per milliliter of the vitamin D measure had a 50% increased risk of having a heart attack compared with men whose blood levels were 30 nanograms per milliliter or higher.
In another study, 3,258 men and women (average age 62) who were scheduled for angiography because of suspected coronary artery disease were followed for subsequent cardiovascular death or death by another cause. People in the study had blood levels of vitamin D drawn at the time of angiography. After 7.7 years of follow-up, 737 people died and 463 of those people died from cardiovascular disease. People with the lowest levels of vitamin D—less than 13.3 nanograms per milliliter—had a higher risk of death from any cause, and a higher risk of death from cardiovascular disease compared with those people whose levels were greater than 28.3 nanograms per milliliter.
Vitamin D may help prevent heart disease by lowering blood pressure, decreasing calcification in the heart vessels, or by other mechanisms. However, the optimal daily level of vitamin D to prevent chronic disease and maintain health is still not known.
“Vitamin D deficiency has been related to an increasing number of conditions and to total mortality,” said Edward Giovannucci, MD, ScD, and his colleagues from the Harvard School of Public Health, Boston, Massachusetts. Dr. Giovannucci comments that the amount of vitamin D required for optimal health may be much higher than the current daily recommendation of 200 to 600 IU per day. This would be especially true for those with minimal sun exposure, added Dr. Giovannucci.
Getting enough vitamin D
Sources of vitamin D include the sun, food, and dietary supplements. People who live in sunny climates who wear less clothing and therefore allow more daily exposure of their arms and legs usually have higher levels of vitamin D compared with people who live in more northern or more cloudy climates.
Food sources of vitamin D are limited but include some fish such as salmon, mackerel, and tuna; cod liver oil; fortified milk; and fortified cereal products. Eggs, fortified margarine, some cheese, and other foods have small amounts of vitamin D.
Ask your doctor about how to get enough vitamin D from appropriate dietary changes or supplements based on your current health.
(Arch Intern Med 2008;168:1174–80; Arch Intern Med 2008;168:1340–9)
Jane Hart, MD, board-certified in internal medicine, serves in a variety of professional roles including consultant, journalist, and educator. Dr. Hart, a Clinical Instructor at Case Medical School in Cleveland, Ohio, writes extensively about health and wellness and a variety of other topics for nationally recognized organizations, Web sites, and print publications. Sought out for her expertise in the areas of integrative and preventive medicine, she is frequently quoted by national and local media. Dr. Hart is a professional lecturer for healthcare professionals, consumers, and youth and is a regular corporate speaker.
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