Your Microbiome & Vitamin D Levels May Be Linked: Study

MONDAY, Dec. 7, 2020 (HealthDay News) -- The diversity, and therefore the health, of the microbes in your gut is linked to your levels of vitamin D, a new study suggests.

The gut microbiome is composed of bacteria, viruses and other microbes that live in our digestive tracts and are important factors in our health and risk for disease.

In this study, researchers analyzed stool and blood samples from 567 men in six U.S. cities (average age: 84). Most rated their health as good or excellent.

The University of California, San Diego investigators found that the makeup of the men's gut microbiome was linked to their levels of active vitamin D, which is important for bone health and immunity.

Vitamin D comes in different forms, but standard blood tests detect only an inactive precursor that can be stored by the body. To use vitamin D, the body must metabolize the precursor into an active form, the researchers explained.

"We were surprised to find that microbiome diversity -- the variety of bacteria types in a person's gut -- was closely associated with active vitamin D, but not the precursor form," said senior author Dr. Deborah Kado, director of the Osteoporosis Clinic at UC San Diego Health.

"Greater gut microbiome diversity is thought to be associated with better health in general," she said in a university news release.

Researchers also found that 12 specific types of bacteria were more common in the gut microbiomes of men with lots of active vitamin D. Most of those 12 types produce a fatty acid called butyrate, which helps maintain gut lining health.

A number of previous studies have suggested that people with low vitamin D levels are at higher risk for cancer, heart disease, more severe COVID-19 infections and other diseases.

But the largest randomized clinical trial to date (more than 25,000 adults) concluded that taking vitamin D supplements has no effect on health, including bone health and the risk of heart disease and cancer.

"Our study suggests that might be because these studies measured only the precursor form of vitamin D, rather than active hormone," Kado said. "Measures of vitamin D formation and breakdown may be better indicators of underlying health issues, and who might best respond to vitamin D supplementation."

"We often find in medicine that more is not necessarily better," said co-author Dr. Robert Thomas, a fellow in endocrinology at UCSD School of Medicine. "So in this case, maybe it's not how much vitamin D you supplement with, but how you encourage your body to use it."

The findings were published Nov. 26 in the journal Nature Communications.

More information

Learn more about gut health at the U.S. National Institutes of Health.

SOURCE: University of California, San Diego, news release, Nov. 30, 2020