Study reveals connection between gut bacteria and vitamin D levels
This study suggests that it doesn't matter how much vitamin D you get through sunlight or supplementation, nor how much your body can store. It matters how well your body is able to metabolize that into active vitamin D
FAB RESEARCH COMMENT:
Some of the many inconsistencies in research into Vitamin D may arise from the way that Vitamin D is usually measured, according to this new study - which also explored links between Vitamin D and the gut microbiota.Numerous studies have linked 'low Vitamin D status' to a wide range of physical and mental health conditions - in keeping with the numerous known roles of this powerful hormone in body and brain health.*
However, findings from clinical trials of Vitamin D supplementation have yielded very mixed evidence to date - and this new research suggests one possible reason for this.
'Active' Vitamin D is very tightly controlled in the body, so most research (and clinical tesring testing) assesses only levels of its precursor. But in this study, the researchers examined levels of the precursor and breakdown products, as well as active Vitamin D in a sample of older men.
They found that active Vitamin D - but not its precursor (the usual measure of Vitamin D status) - was related to measures of gut microbial balance and diversity - suggesting that the gut microbiota may play an important role in Vitamin D metabolism that has been overlooked in research to date.
However, most clinical trials of Vitamin D supplementation have suffered from many other limitations (including failing to take account of baseline Vitamin D status, or using only low dosages).
And with respect to Vitamin D metabolism, other key issues include synergies with other nutrients - including the fact that low magnesium status impairs Vitamin D metabolism. See:
Furthermore, although both Vitamin D and calcium are often supplemented together in studies of osteoporosis, the role of Vitamin K2 (a master regulator of calcium) still remains largely ignored.
Adequate supplies of this nutrient (not the better known Vitamin K1) are needed to ensure that calcium is mobilised as needed to strengthen bones and teeth, rather than being depostied in other organs or soft tissues - incuding arteries - where calcification is a risk factor for both cardiovascular disease and dementia.
For the related research article please see:
For further information on vitamin D please see:
30/11/2020 - Medical Xpress
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Our gut microbiomes—the many bacteria, viruses and other microbes living in our digestive tracts—play important roles in our health and risk for disease in ways that are only beginning to be recognized.
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Our gut microbiomes—the many bacteria, viruses and other microbes living in our digestive tracts—play important roles in our health and risk for disease in ways that are only beginning to be recognized.
University of California San Diego researchers and collaborators recently demonstrated in older men that the makeup of a person's gut microbiome is linked to their levels of active vitamin D, a hormone important for bone health and immunity.
The study, published November 26, 2020 in Nature Communications, also revealed a new understanding of vitamin D and how it's typically measured.
Vitamin D can take several different forms, but standard blood tests detect only one, an inactive precursor that can be stored by the body. To use vitamin D, the body must metabolize the precursor into an active form.
"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 Deborah Kado, MD, director of the Osteoporosis Clinic at UC San Diego Health.
"Greater gut microbiome diversity is thought to be associated with better health in general."
"Greater gut microbiome diversity is thought to be associated with better health in general."
Kado led the study for the National Institute on Aging-funded Osteoporotic Fractures in Men (MrOS) Study Research Group, a large, multi-site effort that started in 2000. She teamed up with Rob Knight, Ph.D., professor and director of the Center for Microbiome Innovation at UC San Diego, and co-first authors Robert L. Thomas, MD, Ph.D., fellow in the Division of Endocrinology at UC San Diego School of Medicine, and Serene Lingjing Jiang, graduate student in the Biostatistics Program at Herbert Wertheim School of Public Health and Human Longevity Sciences.
Multiple studies have suggested that people with low vitamin D levels are at higher risk for cancer, heart disease, worse COVID-19 infections and other diseases. Yet the largest randomized clinical trial to date, with more than 25,000 adults, concluded that taking vitamin D supplements has no effect on health outcomes, including heart disease, cancer or even bone health.
"Our study suggests that might be because these studies measured only the precursor form of vitamin D, rather than active hormone," said Kado, who is also professor at UC San Diego School of Medicine and Herbert Wertheim School of Public Health.
"Measures of vitamin D formation and breakdown may be better indicators of underlying health issues, and who might best respond to vitamin D supplementation."
"Measures of vitamin D formation and breakdown may be better indicators of underlying health issues, and who might best respond to vitamin D supplementation."
The team analyzed stool and blood samples contributed by 567 men participating in MrOS. The participants live in six cities around the United States, their mean age was 84 and most 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 quantify vitamin D metabolites (the precursor, active hormone and the breakdown product) in each participant's blood serum.
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 quantify vitamin D metabolites (the precursor, active hormone and the breakdown 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 particular types of bacteria appeared more often in the gut microbiomes of men with lots of active vitamin D. Most of those 12 bacteria produce butyrate, a beneficial fatty acid that helps maintain gut lining health.
"Gut microbiomes are really complex and vary a lot from person to person," Jiang said. "When we do find associations, they aren't usually as distinct as we found here."
Because they live in different regions of the U.S., the men in the study are exposed to differing amounts of sunlight, a source of vitamin D. As expected, men who lived in San Diego, California got the most sun, and they also had the most precursor form of vitamin D.
But the team unexpectedly found no correlations between where men lived and their levels of active vitamin D hormone.
"It seems like it doesn't matter how much vitamin D you get through sunlight or supplementation, nor how much your body can store," Kado said.
"It matters how well your body is able to metabolize that into active vitamin D, and maybe that's what clinical trials need to measure in order to get a more accurate picture of the vitamin's role in health."
"It matters how well your body is able to metabolize that into active vitamin D, and maybe that's what clinical trials need to measure in order to get a more accurate picture of the vitamin's role in health."
"We often find in medicine that more is not necessarily better," Thomas added. "So in this case, maybe it's not how much vitamin D you supplement with, but how you encourage your body to use it."
Kado pointed out that the study relied on a single snapshot in time of the microbes and vitamin D found in participants' blood and stool, and those factors can fluctuate over time depending on a person's environment, diet, sleep habits, medications and more.
According to the team, more studies are needed to better understand the part bacteria play in vitamin D metabolism, and to determine whether intervening at the microbiome level could be used to augment current treatments to improve bone and possibly other health outcomes.
According to the team, more studies are needed to better understand the part bacteria play in vitamin D metabolism, and to determine whether intervening at the microbiome level could be used to augment current treatments to improve bone and possibly other health outcomes.
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