About Medicine: Vitamin D and heart health

Bradley D. Berry, M.D.
Heart Failure Director
International Heart Institute of Montana
Providence Saint Patrick Hospital

Vitamin D and Heart Health
Vitamin D has long been known to be an important part of good nutrition to promote healthy bone growth, avoid Rickets, and to avoid bone conditions such as osteopenia or osteoporosis. Vitamin D leads to increased absorption of calcium and other minerals from ingested foods. Adequate vitamin D is necessary to manage the amount of calcium in our blood and bones. Nutritional sources of vitamin D are traditionally quite poor as a source of adequate vitamin D. Our bodies get most of its natural vitamin D from exposure to the sun. Synthesis of vitamin D in our skin from exposure Ultraviolet (UV) light converts cholesterol into vitamin D3 which is later converted inside our bodies into an active form.

As a population, we are spending less time in the sun and are more likely to protect ourselves from the harmful effects of UV light with sunscreen or clothing which compound the prevalence of deficiency.

Studies indicate that as many as two thirds of healthy volunteers have low blood levels of active vitamin D and nearly 40% are severely low. It has been noted that certain populations can run rates of deficiency at close to 100%. This effect is further compounded by living in northern latitudes such as western Montana. Risk factors for vitamin D deficiency include older age, living in northern climates, darker skin pigmentation, and obesity. Ideal sun exposure to maintain healthy levels of vitamin D may have harmful side effects, often leading to the need for supplementation.

In recent years, there has been increasing amounts of evidence that low levels of vitamin D are associated with many health issues and conditions. Low levels of vitamin D may be associated with conditions ranging from muscle and joint pain to a variety of cancers including colon, breast, prostate, esophagus, and the ovaries. Other serious conditions have been linked to low levels of vitamin D including hypertension (high blood pressure), diabetes, and immune conditions such as rheumatoid arthritis and multiple sclerosis.

In addition to diseases that increase the risk of heart disease such as diabetes and hypertension, there is significant evidence related to the association of low vitamin D levels and actual heart diseases.

Studies have indicated a relationship with vitamin D deficiency and heart attacks, strokes, congestive heart failure, rhythm disorders, and peripheral arterial disease. One Harvard study indicated Vitamin D deficient patients were at twice the risk of similar non-deficient patients for a heart attack. Studies have also indicated that very low levels may take on higher risk than mildly low levels. Italian studies have demonstrated a very high prevalence of vitamin D deficiency in patients suffering heart attacks throughout all seasons, but in summer months, with increased sun exposure, the prevalence was less.

Vitamin D may decrease risk through a variety of means including decreasing inflammation, hypertension and diabetes, arterial wall thickening, and arterial wall calcification. Normalizing vitamin D levels with supplementation can normalize parathyroid hormone. This is important because parathyroid in our blood rises in vitamin D deficiency in response to lower circulating calcium to maintain normal blood levels of calcium. In addition to weakening bones and leading to osteoporosis, high parathyroid hormone levels are inflammatory to blood vessels and are associated with vascular events such as heart attack and stroke.

The best evidence suggests that avoiding deficiency of vitamin D may decrease your risk for cardiovascular disease. There are several studies that indicate treating vitamin D deficiency with supplementation will decrease future risk, avoid poor outcomes, and decrease complications of cardiovascular disease. Early studies have shown promising results in treatment of cardiac disease.

Treating vitamin D deficiency with supplements appears to be involved in preventing and reducing risk of cardiovascular disease. Funding for such research is difficult, and larger studies has been lacking but some larger studies are underway. Studies have indicated that the use of vitamin D supplements has been associated with better tolerance of certain cholesterol medications common in cardiac patients.

In our own research focusing on patients with congestive heart failure and vitamin deficiency, we demonstrated dramatic improvement of quality of life as compared to placebo. This is important as many studies of congestive heart failure have demonstrated standard or guideline based therapies will improve survival but may be associated with decreased quality of life over the course of the study.

Additionally, hormonal markers for heart failure and exercise markers were improved in our study and demonstrated a marked reduction in parathyroid hormone in the treatment group. Many studies of vitamin D supplementation in cardiac disease have had issues with appropriate dosing and often don't provide sufficient dosing to overcome deficiency. Inadequate dosing is an issue with current guidelines for vitamin D supplementation in general as there is evidence that the national daily requirement recommendations leave many patients deficient, especially the most vulnerable patients.

The appropriate dose for any person should be discussed and decided on in consultation with their physician. Vitamin D supplementation has been demonstrated to be very safe. Toxicity occurs only at very high non-recommended doses and is rare in the absence of other medical conditions. The potential health benefits are many both for prevention, as well as treatment of many conditions including cardiac diseases in conjunction with other appropriate medications. Often, monitoring levels of vitamin D is helpful as people absorb, convert, and utilize vitamin D at very different rates. Always discuss supplement additions or dose changes with your healthcare provider as interactions with existing medications and conditions are possible.

This community health column is brought to you by Marcus Daly Memorial Hospital, Marcus Daly Cardiology Services and The International Heart Institute of Montana. For questions and or comments, please contact Bradley D. Berry, M.D., Heart Failure Director, International Heart Institute of Montana. Working together to build a healthier community!