Vitamin D and Your Gut

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The Pure TheraPro Team

The Pure TheraPro Education Team is comprised of researchers from diverse backgrounds including nutrition, functional medicine, fitness, supplement formulation & food science. All articles have been reviewed for content, accuracy, and compliance by a holistic integrative nutritionist certified by an accredited institution.
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Are your gut issues related to your low vitamin D levels? There appears to be a link. 

It is estimated that about 80% of the individuals are vitamin D deficient, and research is showing that these low levels are linked to gut dysbiosis, inflammation and autoimmune disease. Studies show that vitamin D increases microbiome diversity.

The human microbiome consists of an entire community of microorganisms that contain about 12 different phyla or families composed mostly of Bacteroidetes, Actinobacteria, Proteobacteria, Firmicutes and Euryarchaeota. They serve important roles in our gut from helping us to absorb and utilize nutrients by promoting and assisting digestion of the food we eat to mediating our immune system. 

The gut microbiome is a key component to health or disease and plays a role in what we know of as autoimmune disease. It is believed that foreign microbial peptides might cause “molecular mimicry,” meaning that they share structure and sequence with self-antigens and may therefore implode on themselves, destroying healthy cells instead of firing at pathogenic invaders when things go wrong. What might cause things to go wrong? Environmental toxins, overuse of antibiotics, chemicals, pathogens, nutrient deficiencies, chronic stress and illness--all of these may kill off colonies of good bacteria or cause miscommunication within the intricate balance of our microbiome and result in misfiring. 



Secretory IgA is the immune system barrier that protects the intestinal lining from permeability by toxins and pathogens. Any disruption here creates vulnerability. Higher levels of vitamin D, however, may support a stronger, more intuitive Secretory IgA barrier, tighter gut junctions and greater abundance and communication of pathogen-fighting good microorganisms, according to research. 

In a cross-sectional study of healthy individuals, low vitamin D intake was associated with a dysbiosis between Prevotella and Bacteroides bacterium. Eight weeks of vitamin D3 supplementation increased species diversity and decreased “bad” bacteria in the upper GI tract while increasing "good" bacteria.

Aside from microbiome diversity, vitamin D also plays a role in reducing inflammation and regulating immune cell activity. Low levels of vitamin D are part of the domino effect resulting in immunoregulatory dysfunction. BECAUSE low levels of vitamin D seem to negatively impact bacterial communities, the chain reaction can affect intestinal barrier function (secretory IgA) and genetic polymorphisms (resulting in autoimmune disease and chronic illness). It’s a cause and effect chain. Although a genetic predisposition must exist, non-genetic factors such as low vitamin D levels impacting the gut microbiome may create a scenario that makes one susceptible to dis-ease. 

Vitamin D works directly with the immune system and your microbiome. They are interconnected. A University of California San Diego study furthered this relationship by studying the gut microbiome of older men in connection with their vitamin D levels. The study also looked deeper at vitamin D forms, biomarkers and metabolism of vitamin D from the precursor to active form. 

The researchers discovered that microbiome diversity was not only related to vitamin D levels as measured in blood tests but how well someone can metabolize vitamin D from the precursor to the active form. It is believed that the greater the microbiome diversity, the greater health outcomes for an individual. The greater the microbiome diversity, the greater the metabolism of vitamin D to its active form.



Men in the study who had high levels of active vitamin D and high microbiome diversity were also found to have guts that included the 12 specific bacteria species that produce a beneficial fatty acid, butyrate, which is instrumental in gut health and a healthy gut mucosal lining (Remember that the gut lining is a vital force of immune function). 

The study also noted that how much vitamin D someone gets through sunlight or supplementation might be irrelevant. What matters is how well the body is able to metabolize vitamin D from the precursor form to the active form, but unfortunately, clinical studies haven’t focused much on this element of the domino effect to get a better scope of vitamin D’s role in promoting optimal gut health. It does appear, however, that vitamin D is a key player in this complicated relationship between microbiome diversity and its mediation with the immune system and gut lining.

One takeaway is the importance of optimizing nutrient absorption including vitamin D absorption by supporting gut health and a strong immune system. 


Our Leaky Gut Defense includes ingredients that help soothe and rebuild the mucosal gut lining as well as create an environment that is conducive to a healthy, flourishing microbiome. One such ingredient, Arabinogalactan, interacts with M-cells. M-cells are the communication experts residing in the lymphoid tissue and mediate the digestive tract’s immune function. Studies show that arabinogalactan activates these M-cells, which creates a domino effect, initiating T-cells and other immune system fighters throughout the body. 



Arabinogalactan is also slowly fermented by bacteria in the colon. Being difficult to digest, this fermentation process attracts good bacteria and creates essential short-chain fatty acids that further promote gut health.

Arabinogalactan helps create more butyrate and proprionate in the gut, which are two short chain fatty acids instrumental in fighting cancer-causing agents and protecting the lining of the intestinal wall. They attract bifidobacteria and lactobacillus, two friendly gut bacteria that help promote gut health.

Bifidobacterium longum also feeds and ferments off arabinogalactan and helps sustain a healthy microbiome. Studies indicate that fatty acids such as butyrate and a diverse microbiome play an important role in optimizing health. 


Of course, supplementing with vitamin D is also important. Our Vegan D3+K2’s upcoming production run will include micellized vitamin D3. The micellization of vitamin D provides increased bioavailability. Micellization creates extremely small clusters of water-soluble fat that is nearly identical to fat created intrinsically by our small intestine. Many people with absorption issues have been able to absorb micellized forms of fat soluble vitamins more efficiently than regular forms.



According to studies, micellization of D3 increases serum 25 (OH) by five times compared to emulsified vitamin D, so it may be the best option for those with absorption issues.


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