Vitamin D: New Way to Treat Heart Failure?

Strong bones, a healthy immune system, protection against some types of cancer: Recent studies suggest there’s yet another item for the expanding list of vitamin D benefits. Vitamin D, “the sunshine vitamin,” keeps the heart, the body’s long-distance runner, fit for life’s demands.

University of Michigan pharmacologist Robert U. Simpson, Ph.D., thinks it’s apt to call vitamin D “the heart tranquilizer.”

In studies in rats, Simpson and his team report the first concrete evidence that treatment with activated vitamin D can protect against heart failure. Their results appear online ahead of print in the Journal of Cardiovascular Pharmacology.

In the study, treatments with activated vitamin D prevented heart muscle cells from growing bigger – the condition, called hypertrophy, in which the heart becomes enlarged and overworked in people with heart failure. The treatments prevented heart muscle cells from the over-stimulation and increased contractions associated with the progression of heart failure.

About 5.3 million Americans have heart failure, a progressive, disabling condition in which the heart becomes enlarged as it is forced to work harder and harder, making it a challenge even to perform normal daily activities. Many people with heart disease or poorly controlled high blood pressure go on to experience a form of heart failure called congestive heart failure, in which the heart’s inability to pump blood around the body causes weakness and fluid build-up in lungs and limbs. Many people with heart failure, who tend to be older, have been found to be deficient in vitamin D.

“Heart failure will progress despite the best medications,” says Simpson, a professor of pharmacology at the U-M Medical School. “We think vitamin D retards that progression and protects the heart.”

The U-M researchers wanted to show whether a form of vitamin D could have beneficial effects on hearts that have developed or are at risk of developing heart failure. They used a breed of laboratory rats predisposed to develop human-like heart failure.

The researchers measured the effects of activated vitamin D (1,25 dihydroxyvitamin D3, a form called calcitriol) in rats given a normal diet or a high-salt diet, compared to control group rats given either of the same two diets, but no vitamin D treatment. The rats on the high-salt diet were likely to develop heart failure within months.

The rats on the high-salt diet, comparable to the fast food that many humans feast on, quickly revealed the difference vitamin D could make.

“From these animals, we have obtained exciting and very important results,” Simpson says.

After 13 weeks, the researchers found that the heart failure-prone rats on the high-salt diet that were given the calcitriol treatment had significantly lower levels of several key indicators of heart failure than the untreated high-salt diet rats in the study. The treated rats had lower heart weight. Also, the left ventricles of the treated rats’ hearts were smaller and their hearts worked less for each beat while blood pressure was maintained, indicating that their heart function did not deteriorate as it did in the untreated rats. Decreased heart weight, meaning that enlargement was not occurring, also showed up in the treated rats fed a normal diet, compared to their untreated counterparts.