In this article, we will discuss the role of vitamin D3 and lung health, and whether vitamin D supplementation is beneficial.
Vitamin D3 supplement often helps with respiratory tract infections
When we take vitamin D3, it gets converted into 25-hydroxy vitamin D (25D) in the liver and then to the hormonal form 1,25-dihydroxyvitamin D (calcitriol) in the kidneys1. Calcitriol can then activate the vitamin D receptors (VDR), which combine with a vitamin A receptor called RXR to turn on certain genes.
The innate immune response prevents the viruses from entering the cells. In the lungs, VDR activation leads to production of antiviral peptides such as cathelicidin and defensin-2 into the mucus that line the airway, which are part of our innate immune response2,3. By boosting the innate immune response, vitamin D may reduce the incidences of flu4,5,6.
Once the viruses infect the cells and start to expand, VDR activation prevents the immune system from going overboard with fighting off the virus, which may explain why vitamin D supplementation may reduce the severity of flu4,5,6.
Vitamin D also appears to help with many lung conditions, including asthma, chronic obstructive pulmonary disorder, and tuberculosis in addition to common colds and flus7.
The antiviral and lung-protecting role of vitamin D might explain why vitamin D appears to be protective against respiratory tract infections according to several meta-analyses8,9. However, some studies demonstrated no benefits, possibly because only severely vitamin D deficient people would benefit from vitamin D supplementation, especially people with darker complexion10.
Why vitamin D supplementation may not be the answer
Vitamin D deficiency is remarkably common, affecting ~ 1 billion people worldwide, especially the elderly11. The standard of care for these individuals is to recommend vitamin D supplementation, but this recommendation is shortsighted!
Low 25-D levels and lower sun exposure strongly correlate with autoimmune disease and chronic inflammation. Interestingly, many autoimmune patients have elevated levels of calcitriol while their 25-D level is very low12. Clinically, our founders and colleagues observe that many of our patients with chronic inflammation, obesity, and cancer have very low 25-D levels. In addition, even very high doses of D3 supplementation for months cannot restore healthy vitamin D levels. Possibly, vitamin D supplementation in this group may not be beneficial because their bodies are clearly resisting it.
High blood lipopolysaccharide is a marker of leaky gut from unhealthy diets (metabolic endotoxemia), which can contribute to obesity, diabetes, hypertension, and cardiovascular disease13. Lipopolysaccharides inhibit vitamin D receptor function14. Inhibiting VDR not only prevents vitamin D from reducing inflammation but also prevents the breakdown of active vitamin D, causing a build up of it in the blood12.
As such, chronic inflammation may cause low blood 25-D level when there is vitamin D receptor resistance15,16.
Cold viruses and many other pathogens also protect themselves by reducing vitamin D receptors, reducing vitamin D activation, and increasing vitamin D breakdown3. Despite these vitamin D receptor inhibitions, vitamin D supplementation remains beneficial, but are rarely considered as part of treatment.
Also, the inflammation-related vitamin D receptor resistance may also hamper the appropriate immune response, thus worsening their prognosis for any infections.
The key is to restore vitamin D receptor function, not vitamin D levels
In order to restore vitamin D receptor function, it is important to address infections and repair leaky gut. To repair leaky gut, you need to eat a healthy anti-inflammatory diet and support your gut bacteria.
A healthy gut microbiome helps reduce lipopolysaccharides and chronic low-grade inflammation in many different ways. One of the ways our friendly gut bacteria help balance the immune response is by improving vitamin D receptor function17,18.
Our patented tributyrin delivery system in Complete Biotic makes the butyrate more bioavailable throughout the body. Tributyrin can increase vitamin D receptor function in gut lining cells in cell-based studies19,20. Therefore, Complete Biotic can help promote a healthy and balanced immune response by improving vitamin D receptor function.
