Six studies confirm the health benefits of vitamin D

We often see headlines mentioning a chemical or vitamin has astonishing new health benefits, only to have those claims fall apart under more thorough investigation. Vitamin D is looking like it might be an exception. Science News highlights six studies on the vitamin’s health benefits:

• An analysis of 24 clinical trials in children finds that kids getting vitamin D supplements had a 47 percent reduced risk of dental caries, researchers report in Nutrition Reviews.

• A study of 242 healthy adults getting daily calcium supplements shows that those who also took modest vitamin D supplements of 800 IU per day saw their blood pressure decrease. Their top blood pressure number fell by 10 points on average after a year and their bottom BP number fell by four points. Writing in Nutritional Influences on Bone Health, the researchers also report that the vitamin D folks saw their heart rate decline from 74 to 70 beats per minute. The calcium-only group saw no improvement on average.

• A 28-year study in which Danish scientists monitored the health of nearly 10,000 people finds that those who developed a tobacco-related cancer during that time had vitamin D levels at the study outset of 14.8 nanograms per milliliter of blood on average, compared with 16.4 ng/ml on average for everyone else. That report shows up in Clinical Chemistry.

• BMJ reports in a review of 31 studies that pregnant women with vitamin D levels of less than 30 ng/ml had an increased risk of developing a complication such as preeclampsia or gestational diabetes.

• Low vitamin D levels may hamper metabolism in blacks. A study in Nutrition Research finds that adult blacks averaged vitamin D of only 14.6 6 ng/ml compared with 25.6 ng/ml on average in whites. Blacks were also more likely to have insulin resistance, a condition in which cells fail to use the hormone insulin efficiently to process glucose. But when researchers compared groups with similar vitamin D levels, the differences in insulin resistance disappeared. That suggests that the higher burden of insulin resistance in blacks is at least in part the result of low vitamin D, they conclude.

• Very low vitamin D might be linked to suicide risk. An analysis of military service members finds that people who committed suicide appear to have similar vitamin D levels on average compared with those who don’t. But a closer look finds that people with the very lowest levels, less than 15 ng/ml, were roughly twice as likely to commit suicide as people with vitamin D ranging from 17 to 41 ng/ml. That study appears in PLoS One.