Better health … study reveals the relationship between gut bacteria and vitamin D.

The Nature Communications study also revealed a new understanding of vitamin D and how it is usually measured.

“We were surprised that the diversity of the microbiome – the different types of bacteria in a person’s gut – was closely related to the active vitamin D, but not the precursor form,” said senior researcher Deborah Cadeau, director of Osteoporosis. Clinic. At UC San Diego Health.

“Greater diversity in the gut microbiome is believed to be linked to better overall health,” added Cadeau.

Cadeau led the study for the National Institute on Aging-funded Research Group for the Study of Osteoporosis in Men (MrOS), a large, multi-site effort that began in 2000.

Collaborated with Rob Knight, Ph.D., professor and director of the Center for Microbiome Innovation at the University of California, San Diego, and co-authors Robert L. Thomas, MD, Ph.D., Fellow in the Department of Endocrinology at the University of California Medical School in San Diego, and Serene Lingjing Jiang, graduate student of the biostatistics program at the Herbert Wertheim School of Public Health and Human Longevity Sciences.

However, the largest randomized clinical trial to date, with over 25,000 adults, concluded that taking vitamin D supplements had no effect on health outcomes, including heart disease, cancer, or even the health of women. bones.

“Our study suggests that the reason for this is that these studies only measure the elemental form of vitamin D, not the active hormone,” said Cadeau, who is also a professor at UC San Diego School of Medicine and Herbert Wertheim School. of Public Health.

“Measurements of vitamin D composition and breakdown may be better indicators of underlying health problems and who might respond best to vitamin D supplementation,” added Cadeau.

The team analyzed stool and blood samples provided by 567 men participating in MROS. Participants lived in six cities in the United States, with an average age of 84, and most of them reported being in good or excellent health.

The researchers used a technique called 16s rRNA sequencing to identify and quantify the types of bacteria in each stool sample based on unique genetic identifiers. They used a method known as LC-MSMS to determine the vitamin D metabolites (precursor, active hormone, and hydrolysis product) in each participant’s blood serum.

In addition to discovering a link between active vitamin D and overall microbiome diversity, the researchers also noted that 12 specific types of bacteria appeared more often in the gut microbiomes of men who had too much active vitamin D. Beneficial fatty acids that help maintain a healthy intestinal lining.

“Gut microbes are really complex and differ a lot from person to person. When we find associations, they’re usually not as distinct as we’ve found here,” Jiang said.

Because they live in different regions of the United States, the men in the study are exposed to varying amounts of sunlight, which is a source of vitamin D. As expected, the men who lived in San Diego, California received more sunlight and had also the greatest number of vitamin D precursors.

But the team unexpectedly found no correlation between where the men lived and their levels of the active vitamin D hormone.

Cadeau added: “It is important to what extent your body can metabolize it into active vitamin D, and perhaps this is what clinical trials need to measure to get a more accurate picture of the vitamin’s role in health.”

Thomas added: “In medicine, we often find that more is not necessarily better. So, in this case, it might not be about how much vitamin D you get, but how to encourage the body to use it.”

Cadeau pointed out that the study was based on a single timely shot of the microbes and vitamin D found in the participants’ blood and feces, and these factors can vary over time depending on the person’s environment, diet, habits of the sleep, medication, etc.

According to the team, more studies are needed to better understand the role of bacteria in vitamin D metabolism and determine whether a microbiome-level intervention could be used to augment current treatments to improve bone and possibly other health outcomes.