In the journals
Adequate levels of vitamin D can help strengthen bones and lower the risk for diabetes and some cancers. But research published online April 5, 2017, by JAMA Cardiology found that high monthly doses of supplemental vitamin D did little to ward off cardiovascular disease.
The recommended daily amount of vitamin D is 600 international units (IU) for men ages 51 to 70 and 800 IU for men ages 71 and older. It is not yet clear how vitamin D may improve heart health, but studies have found a higher rate of cardiovascular disease among people with low levels of vitamin D.
Previous research showed that low-dose supplementation (400 IU daily) had no effect in preventing cardiovascular disease, so researchers wanted to explore whether higher monthly dosages might be better. Approximately 5,000 people, 58% of them men, received an initial dose of 200,000 IU of vitamin D. A month later, they were split into two groups: every month, those in one group took a 100,000-IU dose of vitamin D, and the others a placebo, for more than three years.
By the end of that period, cardiovascular disease had occurred in about the same number of people in each group — 11.8% of those in the supplement group, and 11.5% of those in the placebo group. Cardiovascular disease was measured by whether they developed conditions like heart attack, stroke, pulmonary embolism, or high blood pressure.
The researchers added that while a high monthly dosage did not prove effective, it is possible that a daily or weekly dose in other amounts may have a different outcome, and more research is needed.