I have lately been discussing a variety of ways to boost the immune response, given current concerns with the COVID-19 pandemic. Among the topics we have discussed are boosting T-cell immunity with vitamin D; reduction of metabolic endotoxemia by eliminating the gliadin protein of wheat and eradicating small intestinal bacterial overgrowth, SIBO; reversing thymic involution by boosting oxytocin via L. reuteri yogurt; and reducing potential for respiratory viruses with Lactobacillus casei Shirota. This is not fluff; these are exceptionally powerful ways to augment immunity. It won’t make you impervious to viral infections, of course, but can stack the odds in favor of minimizing or abbreviating viral infections. This is how we do it in the Undoctored lifestyle: We do NOT “treat” health conditions; we address the factors that allow disease to emerge in the first place. We don’t treat coronavirus or other viruses; we take steps to augment the immune response to provide better protection.
But there is a popular argument that zinc supplementation can improve immunity to viral illnesses. Is this true?
There is no question that zinc is essential for function of the immune system. Worldwide, it is estimated that 20-30% of the world’s population, especially in the developing countries of Africa and Asia, has at least intermittent zinc deficiencies that are associated with impaired learning and growth in children, increased susceptibility to viral infections, increased allergies, and cancer. In these populations with malnutrition, zinc replacement has life-saving effects.
But what can we expect in developed countries in which zinc deficiency is less severe? Are there immune benefits for people like us? While the evidence is mixed, on the whole it suggests that zinc supplementation can shorten the duration of the common cold (doses of 9-24 mg every 2 hours) and perhaps other viral illnesses (especially genital warts improved with topical zinc preparations, another viral illness due to human papillomavirus, HPV).
But there are a few issues to be aware of in deciding whether or not zinc supplementation is of any benefit for us on the Undoctored or Wheat Belly lifestyles:
- Because we eliminate all wheat and related grains from the diet, we have eliminated the dominant source of dietary phytates that bind zinc (and other positively-charged minerals) in the gut and cause them to be passed out in the toilet. Just as wheat/grain consumption contributes to deficiencies of iron, magnesium, manganese, and calcium, it also contributes to zinc deficiency. Zinc deficiency can occur even with adequate intake of dietary zinc, especially in people with diets over-reliant on phytate-rich foods such as rice, corn, and wheat. Eat no wheat or grains is therefore a substantial advantage in zinc status.
- Because the foods richest in zinc are from animal products, vegans, vegetarians, and people who eat minimal quantities of animal products are at risk for zinc deficiency, especially if wheat/grains remain a part of their diet.
- Elderly institutionalized people who are zinc deficient experience a reduction in viral infections over one year by taking zinc gluconate, 45 mg per day.
- Several studies have failed to show any amplification of the immune response after vaccine administration.
- Adding zinc to conventional therapies for hepatitis C yielded no substantial advantage to treatment efficacy
It is therefore unlikely that zinc supplementation provides an immune advantage to someone who does not consume grains and includes zinc-rich foods in their diet. Preliminary evidence even suggests that supplementation in those who are not zinc-deficient can impair the immune response. In other words, supplementing zinc in someone without deficiency is like topping up the gas tank in your car in the hopes that it goes faster—it doesn’t work. Deficiency can be corrected to advantage, but further supplementation in someone who is not deficient cannot drive a process to higher levels and may even be harmful.
I believe that a clearer picture is emerging: In a well-fed U.S. population, wheat and grain consumption coupled with lower zinc intakes in some populations (vegans, vegetarians, and the elderly) are responsible for the appearance of modest benefit with zinc supplementation. However, if you are not consuming wheat and grains and include animal products in your diet, as well as a varied intake of nuts, seeds, and plant products, it is unlikely that zinc yields any benefit in boosting your immune response.
Here is a list of zinc content of various foods, as provided by the USDA Nutrient Database and the National Institutes of Health Office of Dietary Supplements. (“Percent DV” = percent daily value for adults with 11 mg per day zinc intake regarded as adequate. The zinc needs of most adults are confidently met with an intake of 15 mg per day)