Vitamin D and Immunity

Weight Loss


In light of the struggles with the coronavirus pandemic we are having, I have been discussing some ways to augment the immune response and perhaps stack the odds in your favor of not getting the disease if you are exposed, or abbreviating and softening the course if you do get it. I’ve previously discussed some unconventional strategies such as reversing thymic involution with L. reuteri yogurt and oxytocin, reducing the metabolic endotoxemia of SIBO, and supplementing L. casei Shirota to amplify resistance to respiratory viruses. Let’s now discuss vitamin D’s role in the immune response.

In addition to vitamin D’s effects on bone health, muscle strength, insulin sensitivity, mental clarity, and hormonal modulation, vitamin D is also known to play a major role in the immune response. The immune effects of vitamin D manifest as reduced potential for autoimmune diseases (e.g., type 1 diabetes and multiple sclerosis) and cancer. But vitamin D also plays a crucial role in generating a vigorous immune response. One of the ways that vitamin D status is reflected in infection is the seasonal fluctuation in influenza and the common cold that both peak in winter when vitamin D blood and body levels are lowest, both viral illnesses decreasing to virtually nothing in summer.

The immune supporting effects of vitamin D are multi-faceted with effects that include:

  • Stimulation of monocytes and macrophages–i.e., cells that attack invaders pathogenic bacteria, fungi, and viruses.
  • Stimulation of the expression of anti-microbial peptides by neutrophils, monocytes, natural killer cells, and in cells lining the respiratory tract.
  • Stimulation of dendritic cells that present antigens to T-lymphocytes and to B-lymphocytes that produce antibodies.
  • Increases IL-10 that, in turn, activates T-lymphocytes that play a major role in immunity. (This same biomarker is also triggered by our L. reuteri yogurt and oxytocin.)
  • Decreases inflammatory IL-17–Once again, adding to the effect on this inflammatory mediator generated by L. reuteri yogurt and oxytocin.

A recent clinical trial in children given small doses of vitamin D3 (300 units) cut respiratory infections in half, even though 25-hydroxy vitamin D levels were increased from 7 ng/ml to only 19 ng/ml, while 4000 units of D3 given to people with immune impairment or susceptibility to repeated respiratory infections experienced a reduction in frequency of infections, a reduction in nasal pathogens, and reduced need for antibiotics. Another study reported no benefit with vitamin D3, 100,000 units per month, though this study was criticized due to the high starting levels of 25-OH vitamin D of 29 ng/ml and the once-per-month dosing regimen (that has been shown to be inferior to daily dosing).

The role of vitamin D plays out in a practical way, also, in that those of us following the Wheat Belly lifestyle that includes restoration of a 25-hydroxy vitamin D blood level to 60-70 ng/ml rarely get ill with viral illnesses, even while those around you are cough, sneezing, and running fevers. And, as with other strategies in the Wheat Belly arsenal, there also seem to be important synergies among our strategies. If both L. reuteri/oxytocin and vitamin D stimulate IL-10 that stimulates the immune response, do we obtain a further boost by combining them?

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