No, you are not getting enough essential nutrients for keeping a healthy immune system.
In the past two years, there has been much focus on the importance of vitamin D and how it associates with COVID disease outcomes. Perhaps you are already taking vitamin D supplements to support your immune system. But is that all? Are there any other dietary supplements for maintaining or boosting immunity? Let’s find out together.
- Why is your immune system weakened?
First, we need to understand that our immune system function is dynamic, meaning it is not always functioning in the same way. What we eat and our lifestyle can affect our immune function. Factors such as chronic diseases, old age, nutritional deficiencies, chronic obesity, and mental stress can all weaken our immune system.
While we cannot modify our age, we have much more control over our nutritional status.
- Myth: No one needs to take supplements with a balanced diet
Many researchers argue that no one should take supplements if they are on a balanced diet. But the truth is that most Americans do not have an adequate intake of many essential nutrients.
A recent National Health and Nutrition Examination Survey (a biannual cross-sectional study of the US population conducted by the CDC) evaluated data from 26,282 adults aged 19 to 99.
According to the study, 95% of the US adult population had inadequate vitamin D intake, and 84% had inadequate vitamin E intake. Furthermore, 45%, 46%, and 15% of the US adult population had deficiencies in vitamin A, vitamin C, and zinc, respectively.
https://www.cdc.gov/nchs/nhanes/index.htm
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7352522/#B10-nutrients-12-01735
- Vitamin C
Vitamin C (L-ascorbic acid) is a water-soluble nutrient that is naturally present in some foods, added to some foods, and available as a dietary supplement. The human body is unable to produce this vitamin. Extensive research has established that vitamin C is a vital nutrient in overall immune health and is the most well-known immune-boosting supplement.
What is the evidence?
A 2013 Cochrane review looked at results from 29 clinical trials involving more than 11,000 people who regularly took at least 200mg of vitamin C daily. They did not find vitamin C to reduce the incidence of colds in the general population. Still, it is associated with a modest reduction in the length and severity of cold symptoms.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8078152/
A 2012 review exploring the treatment of the common cold in pediatric patients and adults found that prophylactic vitamin C moderately diminished the duration of cold symptoms but not the prevalence of colds in both patient populations.
https://pubmed.ncbi.nlm.nih.gov/22962927/
Although the evidence does not say taking vitamin C every day will prevent a person from getting a cold, a consistently sufficient level of vitamin C does appear to shorten the course of illness. For me, even one less day of runny and stuffy nose is worth it.
So, how much vitamin C do you need?
According to the 2015-2020 Dietary Guidelines for Americans, the recommended daily value of vitamin C changes with age. Adults need more daily vitamin C than children; men also need a little more than women.
https://ods.od.nih.gov/factsheets/VitaminC-HealthProfessional/
Smokers have a significantly lower plasma level of vitamin C compared with nonsmokers. While I am not suggesting vitamin C can improve chronic smokers’ overall health, the study showed vitamin C could improve blood vessel functions.
https://www.ahajournals.org/doi/full/10.1161/01.cir.94.1.6
What about side effects?
Generally, excess vitamin C is excreted through urine. But too much of it can cause diarrhea, nausea, and abdominal cramps. People with decreased kidney function need to watch how much they take, and it is generally a good idea to talk to your doctor before starting it.
What about vitamin C and COVID?
A Spain study saw that up to 82% of critically ill patients had low vitamin C values. A systematic review, however, did not see a significant benefit with vitamin C given in COVID-19 patients.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8269403/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8552785/
If you ask my opinion, I tend to think vitamin C’s effect on the immune system has more of a chronic management role. That means taking a short course of high-dose vitamin C may not going to do much immediately for people who are already sick. But if a person constantly maintains an adequate level of vitamin C, then it is possible to have some beneficial effect on the disease outcome.
- Zinc
Zinc is an essential trace mineral with multiple roles in the body, including normal growth and the development of reproductive organs. Zinc is also involved with T-cell development, differentiation of T helper and T killer cells, and T-cell and B-cell activation signaling.
What is the evidence?
A 2015 meta-analysis of 3 randomized trials reported that the use of zinc acetate lozenges for the common cold (dosages of 80-92 mg/day) reduced the duration of many common cold symptoms, such as runny and stuffy nose, sneezing, sore throat, cough, and muscle ache.
The authors concluded that zinc acetate lozenges (at doses of ≈80 mg/day) might be a beneficial treatment for the common cold when started within 24 hours of symptom onset and used for less than two weeks.
https://pubmed.ncbi.nlm.nih.gov/25888289/
A 2006 small randomized clinical trial determined that there is evidence supporting the use of oral zinc in pediatric patients to treat and prevent the common cold. They found that prophylactic use of zinc sulfate at a dose of 15 mg/day during respiratory illness season resulted in a noteworthy reduction in the number of colds and days absent from school.
https://pubmed.ncbi.nlm.nih.gov/16982486/
So, how much zinc do you need, and how to take zinc supplements?
Zinc is most effective when taken 1 hour before or 1 hour after a meal, but if your stomach cannot tolerate it, it is also ok to take that with food.
Long-term use of zinc, especially in high doses, is not typically recommended, may cause copper deficiency, and may increase the risk of urinary tract issues.
Since most dietary zinc is obtained from animal products, vegetarians may need higher amounts of zinc because diets high in fiber can reduce zinc absorption.
https://ods.od.nih.gov/factsheets/Zinc-HealthProfessional/
What about Zinc and COVID?
Similar to vitamin C, an observational study also identified a significant number of COVID-19 patients with zinc deficiency early on during the pandemic. And it is associated with worse disease outcomes.
https://pubmed.ncbi.nlm.nih.gov/32920234/
Unfortunately, a small open-labeled clinical trial using high-dose zinc and vitamin C to treat non-hospitalized COVID-19 patients did not show improvement in symptoms.
https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2776305
To sum up, vitamin C and zinc both have shown their role in supporting the immune system. But the evidence leans more toward having an adequate level consistently rather than taking one or both when illness occurs. While we can certainly get the vitamins and micronutrients from food, we may not be eating the right food. Many of us are too busy to fix a good meal every day consistently. So, this is when supplements could make a difference. But if you are taking multiple prescription medications, it is always a good idea to double-check with your primary care doctor before starting a new supplement.
