Health care professionals have long thought of vitamin D as having a sole purpose: preserving bone health.

Until recently, that is.

As a practicing cardiologist and long-time advocate of self-empowering strategies to reduce the risk of heart disease, I am excited about a growing body of research indicating vitamin D may reduce the risk of heart disease.

Heart attacks during winter months

Current research supports the concept that vitamin D may play a role in reducing plaque buildup and in reducing the risk of coronary disease. It shows that vitamin D deficiency contributes to conditions such as high blood pressure, poor insulin sensitivity, inflammation and other fundamental processes that underlie heart disease.

The attention toward vitamin D’s possible role in heart health began when researchers noticed that the farther north you live, the more likely you are to suffer a heart attack. This suggested that exposure to sunlight may somehow protect the heart, perhaps through vitamin D. Not surprisingly, Eskimos are an exception to this pattern. Why? Probably because they eat large quantities of oily fish, a rich source of vitamin D and omega-3 fatty acids.

A New Zealand study of 179 heart attack victims provided further evidence that vitamin D deficiency might cause heart disease. Sufferers of heart attacks showed lower vitamin D levels compared to people who’ve never had a heart attack.

Further, the National Registry of Myocardial Infarction maintained a database of 259,891 heart attacks. This nationwide tabulation showed a 53% increase in heart attacks during sun-deprived winter months compared to summer.

A strong predictor of atherosclerosis

Several studies have demonstrated the striking seasonal variation of heart attacks: more frequent in winter and fewer in summer. Emerging data connects this phenomenon back to vitamin D. In one study of 2,500 postmenopausal women, those with osteoporosis were four times more likely to have a heart attack than women without the disease.

According to a University of Illinois study, the computed tomography (CT) heart scan score (a measure of coronary atherosclerotic plaque) in women with osteoporosis averaged 222 (optimal is zero), while women with normal bone density had far lower average scores of 42.

In yet another recent study, Italian researchers determined that the greater the vitamin D deficiency, the more carotid atherosclerotic plaque was present. The study’s authors concluded that low blood levels of vitamin D were an independent and strong predictor of atherosclerosis.

Bone health, blood pressure and more

New data documents the substantial effects on vitamin D supplementation across the entire spectrum of conditions such as accelerated osteoporosis, high blood pressure, insulin resistance, multiple sclerosis, and cancer of the colon, prostate, bladder, and breast.

Vitamin D is crucial for prevention of osteoporosis and fracture prevention. In fact, vitamin D exerts a far more potent effect than calcium. Intestinal calcium absorption increases up to four-fold when vitamin D levels are brought to normal.

Blood pressure is reduced modestly through vitamin D’s suppression of the blood pressure-raising hormone, renin, an effect similar to the ACE inhibitor class of prescription medications.

Among the most exciting newly-recognized effects of vitamin D supplementation is the body’s enhanced sensitivity to insulin, which counteracts the poor responsiveness seen in pre-diabetes and diabetes. Raising blood vitamin D levels to the normal range reduces blood sugar, which in turn raises HDL (good) cholesterol and reduces triglycerides.

Getting enough vitamin D

Severe vitamin D deficiency easily affects 50% or more of adults. In environments where sun exposure is minimal, deficiency can be as high as 90%. The elderly are more prone to deficiency since the capacity to activate vitamin D in the skin is lost as we age. However, simply living in a sunny climate provides no guarantee against deficiency. Studies in south Florida and Hawaii have demonstrated surprising levels of deficiency. A Florida study measured an average summertime blood active vitamin D level of 26.8 ng/mL, clearly in the deficient range.

Very little vitamin D is obtainable through a normal diet. The only good sources are oily fish like mackerel and salmon providing up to 400 IUs per 3-ounce serving; cod liver oil with 10-200 IUs per teaspoon; milk, providing up to 100 IUs per 8-ounce serving added by USDA regulation; and egg yolks with 20 IUs per yolk. Many adults mistakenly believe that a glass or two of milk every day provides all the vitamin D they need—but it’s not even close.

Vitamin D supplementation will likely be necessary if sun exposure is sporadic, and often even when sun exposure is abundant. Vitamin D3 is the preferred form, since it is far better absorbed than D2. In northern climates or sun-deprived lifestyles, 2,000 IUs per day is a reasonable dose. It’s wise to not exceed 2,000 IUs per day, in agreement with the Institute of Medicine’s recommendation of a safe upper limit, unless instructed to do so by your doctor and based on your blood level.

A multifaceted approach to improving heart health includes vitamin D

While the scientific community is still debating vitamin D’s role in coronary disease prevention, my clinical experience indicates vitamin D is a crucial part of a coronary plaque reversal program.

My clinic follows a multi-faceted approach. First, we document the quantity of coronary atherosclerotic plaque through a CT heart scan. We then guide participants in correcting cholesterol patterns like low HDL and high cholesterol and triglycerides, preferably with a minimum of medication. We advise that patients consume fish oil at a minimum dose of 4,000 mg per day (containing 1,200 mg of a combination of EPA and DHA), along with L-arginine (3,000-6,000 mg twice per day) to support endothelial health.

Lastly, we use vitamin D supplements to raise blood levels of vitamin D to 50 ng/mL (125 nmol/L). Most people in the northern half of the U.S. require 2,000-4,000 IU or more per day in winter, and slightly less in summer. Using this approach, we now have an impressive track record of reducing CT heart scan scores. Reductions of 20-30% in the first year are not uncommon.