Vitamin D Supplement May Improve Blood Pressure, Cholesterol, Insulin

According to a new meta-study, an average supplemental dose of 3,320 IU of vitamin D per day is associated with reduced blood pressure, total cholesterol, hemoglobin A1C, and fasting blood insulin and glucose.

The finding which is published in the journal ‘Engineering’ comes from a new meta-study of 99 randomised, controlled trials from around the world investigating the benefits of vitamin D for cardiomet- abolic health.

The meta-study attempts to explain and distill findings of sometimes inconsistent studies regarding vitamin D. A new, comprehensive review of existing, often conflicting, research on the benefits of vitamin D supple- mentation extracts a fresh view of its value in maintaining cardiometabolic health.

The authors of the meta-study found that taking a median dose of 3,320 International Units (IU) of vitamin D per day, or around 83 micrograms, was associated with several significant cardiometabolic benefits.

These benefits included reduc- tions in systolic and diastolic blood pressure, overall cholesterol, hemo- globin A1C—a marker of type 2 diabetes—and fasting blood glucose and insulin.

The researchers from China and the United States examined the details of 99 randomised, controlled trials (RCTs) published until March 26, 2024. The trials involved 17,656 participants and were conducted among widely varying populations in various global locations.

A key component of the metastudy was a cataloging of differences between the RCTs that might explain their varying conclusions. Once those differences were understood, the authors of the metastudy could re-analyse and compare the RTCs’ data in a more balanced, apples-to-apples manner.

The resulting findings were less hampered by conflicts, and a few special cases relating to specific populations emerged. The researchers found vitamin D supplementation provided the greatest benefit to non-Westerners, people with lower levels of circulating vitamin D in their blood, people with a BMI of under 30, and people ages 50 and older.

Simin Liu, MD, ScD, professor of epidemiology, surgery, and medicine at Brown University, Providence, RI, and corresponding author of the meta-study, described some ways in which the RCTs differed from each other that caused them to arrive at different conclusions.

“Several main sources of heterogeneity in earlier studies that led to conflicting findings relating supple- mentation to cardiometabolic risk factors included ethnocultural background, age, body weight, and study participants’ circulating 25[OH]D levels at enrollment,” he said.