By Densie Webb, PhD, RD
Research has well established that the nutrients and bioactive compounds that foods and beverages provide contribute to the functioning of the immune system in ways that are relevant to antiviral immunity.1 In the wake of COVID-19, the role of nutrition in immunity became a hot topic and has proven more critical than ever. An optimal immune response depends on optimal nutrition to reduce inflammation and oxidative stress and keep infections such as COVID-19 at bay.
Nutrients for Immunity
Frequently, poor nutrient status is associated with inflammation and oxidative stress, which in turn can impact the immune system. Dietary constituents that have high anti-inflammatory and antioxidant capacity include vitamin C, vitamin E, and phytochemicals such as carotenoids and polyphenols. Dietary fiber, fermented by the gut microbiota into short-chain fatty acids, also has been shown to produce anti-inflammatory effects that may help prevent infection.
“There are several studies and reviews on potential effects of nutrition on COVID-19, and I would say the most discussed are vitamin D and bovine lactoferrin, as well as maybe zinc and selenium,” says Joost van Neerven, PhD, a professor of mucosal immunity at Wageningen University & Research in Wageningen, The Netherlands. “There are no official (ie, broadly supported) recommendations on nutrition and COVID-19, but I think when recommending something from a viewpoint of ‘it doesn’t hurt, so why not use it,’ then extra multivitamins/minerals and/or vitamin D would be on my personal list.”
In addition, sufficient protein intake is critical for antibody production, and low levels of micronutrients, such as vitamin A, have been associated with an increased risk of infection.2 Zinc can disrupt the replication of respiratory viruses and prevent acute respiratory distress syndrome and lung damage in COVID-19, especially if zinc intake is increased from previously low levels.3 Vitamin D may prevent viral infection by interacting with cell entry receptors and preventing viruses from infecting cells.2
Monique Richard, MS, RDN, LDN, FAND, IFNCP, RYT, an integrative dietitian, owner of NutritionInsight, and a national media spokesperson for the Academy of Nutrition and Dietetics, says, “In practice, I typically encourage immune support with a variety of foods rich in zinc, vitamin C, magnesium, iron, quercetin, and B vitamins, as well as a focus on hydration, adequate protein, sleep, fresh air, and sun whenever a client is dealing with respiratory infections. But I also have found benefits in using oregano oil or combination products that include echinacea, goldenseal, elderberry, and milk thistle, among others.” While most of these herbal remedies have been researched regarding immune response, there’s little to no research on their efficacy for preventing COVID-19.
Probiotics and COVID-19
The application of probiotics as a possible adjuvant therapy in the prevention and treatment of COVID-19 has been studied and theorized. Several clinical studies included in systematic reviews and meta-analyses have reported that gut microbiota dysbiosis occurs in COVID-19 patients, and it’s well known that probiotics can have a positive effect on the gut microbiome. To date, one clinical study has addressed this question and concluded that, based on the current evidence available, additional trials are warranted to assess the potential role of probiotics in preventing COVID-19.4
Recently, it’s been suggested that treatment with probiotic bacteria using Bifidobacteria and Lactobacillus may provide a significant chance of recovery from COVID-19. Research also has suggested that the involvement of the gut in COVID-19 may be greater and more prolonged than involvement of the lungs in the infection.5 A narrative review of the research suggested that because the probiotics used to produce yogurt exhibit direct angiotensin-converting, enzyme-inhibitory, antiviral, and immune-boosting activities, and since COVID-19 infection involves angiotensin II accumulation, yogurt bioactive peptides hold potential for preventing infection.6
Bottom Line
Nutrition plays a vital role in maintaining the immune system’s ability to prevent infections, and this includes COVID-19. While each individual responds differently to a COVID-19 infection and to nutrition intervention, research has established that many dietary components may play a role. However, the exact roles of each vitamin, mineral, phytochemical, or probiotic are, as yet, not clearly understood.
— Densie Webb, PhD, RD, is a freelance writer, editor, and industry consultant based in Austin, Texas.
References
1. Govers C, Calder PC, Savelkoul HFJ, Albers R, van Neerven RJJ. Ingestion, immunity, and infection: nutrition and viral respiratory tract infections. Front Immunol. 2022;13:841532.
2. Iddir M, Brito A, Dingeo G, et al. Strengthening the immune system and reducing oxidative stress through diet and nutrition: considerations during the COVID-19 crisis. Nutrients. 2020;12(6):1562.
3. Sadeghsoltani F, Mohammadzadeh I, Safari M-M, et al. Zinc and respiratory viral infections: important trace element in anti-viral response and immune regulation. Biol Trace Elem Res. 2022;200(6):2556-2571.
4. Strauss M, Micetic-Turk D, Pogacar MS, Figan S. Probiotics for the prevention of acute respiratory-tract infections in older people: systematic review. Healthcare (Basel). 2021;9(6):690.
5. Fanos V, Pintas MC, Pintas R, Marcialis MA. Lung microbiota in the acute respiratory disease: from coronavirus to metabolomics. J Pediatric Neonatal Individ Med. 2020;9(1):e090139.
6. Gouda AS, Adbelruhman FG, Sabbah Alenezi H, Megarbane B. Theoretical benefits of yogurt-derived bioactive peptides and probiotics in COVID-19 patients — a narrative review and hypothesis. Saudi J Biol Sci. 2021;28(10):5897-5905.
