From Anirva. This article is general information, not medical advice. These statements have not been evaluated by the Food and Drug Administration. This article is not intended to diagnose, treat, cure, or prevent any disease.
Several everyday nutrients have been studied for their role in supporting normal immune system function. Here's what that research actually covers — and what it doesn't.
In this article
Key Takeaways
- Vitamin C, zinc, vitamin D, and probiotics all play documented roles in normal immune system function.
- This research is about supporting general immune function — it does not show that any of these nutrients prevent, treat, or protect against any specific illness, including COVID-19 or any other infection.
- Several other botanicals (olive leaf extract, curcumin, ginseng, ashwagandha, elderberry) have been studied for a possible role in immune-related processes, but the evidence is early and should not be read as disease prevention or treatment.
- A balanced diet is the primary source of these nutrients; supplements can help fill gaps, but aren't a substitute for medical care.
Vitamin C
Vitamin C (ascorbic acid) is an antioxidant that plays a role in normal immune system function, including supporting the activity of certain immune cells (1). Good dietary sources include citrus fruits, kiwis, and guavas. The recommended daily allowance is 75 mg for women and 90 mg for men.
Zinc
Zinc supports the normal function of immune cells and has antioxidant properties. Zinc deficiency has been studied in relation to immune function; the recommended daily allowance is 8 mg for women and 11 mg for men. Dietary sources include dairy, eggs, nuts, seeds, legumes, meat, and shellfish.
Vitamin D
Vitamin D has long been studied for its role in immune function. Research has looked at the relationship between vitamin D levels and respiratory health outcomes (2). Food sources include salmon, mackerel, tuna, beef liver, egg yolks, and cheese; the standard adult RDA is 600 IU per day.
Probiotics
Probiotics are live microorganisms studied for a range of potential benefits, including a possible role in regulating immune cells in the gut (3). Fermented foods such as yogurt, kimchi, kombucha, sauerkraut, and miso are natural sources.
Other Nutrients Studied for Immune Support
A number of other botanicals have drawn research interest for a possible role in immune-related cell processes. This research is generally early-stage, and none of it shows that these ingredients prevent or treat any disease:
- Olive leaf extract — studied for a possible role in supporting certain immune cell activity (4).
- Curcumin — the main compound in turmeric, studied for a possible role in immune cell regulation.
- Korean ginseng (Panax ginseng) — a traditional herb studied in laboratory research for interactions with certain bacteria (5).
- Ashwagandha — an herb used traditionally in Ayurvedic medicine, studied for a possible role in cell-mediated immunity (6).
- Black elderberry — studied for a possible role in the duration of colds and flu symptoms (7).
What the Research Does Not Yet Show
Supporting normal immune function through diet is different from preventing or treating a specific illness. None of the nutrients above have been shown to prevent, treat, or protect against COVID-19 or any other infectious disease. If you have concerns about your immune health or are managing a medical condition, a doctor is the right resource — not a supplement regimen based on this or any other article.
Frequently Asked Questions
Can these supplements prevent COVID-19 or other infections?
Do vitamin C and zinc cure colds?
Should I take these supplements instead of seeing a doctor?
References
- Vitamin C and respiratory infections: a review. PMID: 29099763.
- Vitamin D status and respiratory infection risk. PMCID: PMC3166406.
- Probiotics and immune regulation: a review. PMCID: PMC4006993.
- Olive leaf extract and immune cell activity. PMID: 29149822.
- Panax ginseng and antibacterial interactions: Journal of Ginseng Research. PMCID: PMC3659612.
- Ashwagandha and cell-mediated immunity. PMCID: PMC3252722.
- Black elderberry and cold/flu symptom duration. PMID: 28198157.
