The makeup of a person's gut microbiome is linked to their levels of active vitamin D, a hormone important for immunity, fighting illnesses from cancer to Covid, and for bone health, according to researchers from the University of California San Diego Medical School and Microbiome units.
Vitamin D is actually a group of compounds with the two most important being vitamin D3 (cholecalciferol) and vitamin D2 (ergocalciferol).
D3 is made by the action of sunlight (UVB) on the cholesterol in the lower layers of the skin and both D3 and D2 can be obtained through supplementation.
Diet contains very little – for example in oily fish or in vitamin enriched Vitamin D – and technically, the vitamin D from diet or supplements is inert – it has to be activated by two enzyme steps, one in the liver to make calcifediol and one in the kidneys to make calcitriol. This is the active form and acts on receptor sites all over the body and in the immune system, as if it were a hormone.
Calcifediol is the form of vitamin D measured in blood tests.
Many studies have consistently concluded that people with low vitamin D levels are at higher risk of cancer, heart disease, diabetes, other chronic illnesses and recently COVID-19
However, recently, the largest randomized clinical trial to date, with over 25,000 adults, concluded that taking vitamin D supplements had no effect on improving immunity, health outcomes and even bone health.
The UC San Diego researchers concluded that the problem was that this big study had only measured the precursor form of vitamin D, rather than active hormone.
Professor Kado of the UC San Diego School of Medicine 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."
The study focussed on older men and the team analyzed both stool and blood samples from 567 healthy males (mean age 84). Using micro-RNA sequencing to identify and quantify the types of bacteria in each stool sample, they also quantified vitamin D metabolites (the precursor, active hormone and the breakdown product) and compared the two.
Despite the men coming from different regions of America the ‘health’ of their vitamin D seemed to matter little how much sunlight they had received. The researchers found a clear link between active vitamin D and overall microbiome diversity. Moreover, 12 particular types of bacteria appeared more often in the microbiome of men with high levels of active vitamin D. In particular, most of these 12 bacteria produced butyrate, a powerful short chain ester that improves the gut lining, controls inflammation and can even attack cancer cells.
The gut lining is linked to the immune system, and it varies hugely from person to person. This just may be the connection.
Go to: Butyrate seriously improves your health