Immune-Boosting Nutrition
COVID-19 is still looming, and flu season is right around the corner…
While you may still be wearing your sore, vaccinated arm as a badge of honor (as you should), you aren’t bulletproof from COVID-19, influenza, or even the common cold. Aside from washing your hands, diet and exercise are two of the best (and simplest) ways to protect yourself from illness - so break out the fruity-smelling hand sanitizer and read on to learn about 6 important immune-boosting nutrients.
1. Vitamin D: Sunshine, fortified dairy/juice/breakfast cereals, fish, beef, egg yolks
Over 1/3rd of US adults are deficient in Vitamin D. While many factors are to blame, including skin pigmentation, old age, desk jobs, and geographic location, Vitamin D can be obtained from food.
Vitamin D has anti-inflammatory & anti-microbial roles and is important for interacting with cells in the immune system to help us fight off infection.
Good sources include fortified milk, yogurt, and cereals, fatty fish (salmon, mackerel, herring, cod, tuna, sardines), red meat, and egg yolks.
COVID: While current evidence does not suggest that Vitamin D can prevent COVID, it may lead to less severe symptoms and reduce the risk of death from certain respiratory symptoms.
2. Vitamin C: Citrus fruits, strawberries, peppers, broccoli, tomatoes, kale
This one is probably not a surprise. You might even gulp down an Emergen-C when you feel the sniffles coming on.
Vitamin C is a potent antioxidant with anti-inflammatory functions. While we can’t say for sure whether Vitamin C prevents illness, it may shorten symptoms of the common cold.
COVID: Vitamin C has been utilized in hospitalized patients to combat “cytokine storm”, an inflammatory response that occurs with COVID-19, but more research is needed to investigate the full effects of Vitamin C on COVID-19 symptoms.
3. Zinc: Shellfish, meat/poultry, beans
Zinc is an immune system superstar. Due to its antiviral roles, zinc has been commonly recommended during the COVID-19 pandemic. Supplementing with zinc has been shown to increase key immune cells and inhibit coronaviruses, and may even shorten the duration of the common cold by up to 40%!
Don’t get too excited, though. Over-supplementation of zinc can cause copper deficiency, which comes with nasty side-effects.
Lucky enough to live near the ocean? Oysters boast a significantly large amount of zinc, at about 7x the daily value (DV) per 3 oz serving!
Otherwise, a warm bowl of zinc-filled chicken noodle soup may be “just what the doctor ordered.”
4. Vitamin E & Selenium: Avocados, nuts & seeds, leafy greens, whole grains, fish, eggs, mushrooms
Vitamin E and selenium are major antioxidants that have been shown to enhance immune pathways. They may even increase resistance to respiratory infections.
COVID: Unfortunately, there is not enough evidence to suggest a benefit from Vitamin E or selenium for COVID-19.
5. Omega-3 fatty acids: Fish, seaweed, walnuts, chia seeds, flaxseed, canola oil
Omega-3 fatty acids are an example of a “healthy fat”. They are anti-inflammatory and have been shown to inhibit replication of the influenza virus.
Note: We recommend eating fatty fish like salmon, mackerel, tuna, herring, cod, and sardines at least 1-2x per week, since plant-based types (with the exception of seaweed) are not converted as efficiently by the body.
While the use of omega-3 fatty acids in those with COVID-19 is still controversial, some hospitals are supplementing patients with omega-3 to reduce inflammatory responses. Overall, more research is needed before we can make any recommendations about the use of omega-3s for COVID-19.
What about supplements?
I typically recommend a “food-first” approach, since vitamins and minerals are often absorbed better when they come naturally in food. Also, fruits and vegetables contain other antioxidants that are not found in your typical multivitamin.
However, some people may benefit from supplements. If you are unable to maintain a well-balanced diet, are over 50 years of age, take certain medications (like acid-blockers), have had gastrointestinal surgery, or have certain medical conditions, you may require supplemental vitamins and/or minerals. Ask your healthcare provider if you may benefit from vitamin or mineral supplements.
Can you spot all of the immune-boosting foods on your dinner plate tonight?
References:
Jeffery L.E., Burke F., Mura M., Zheng Y., Qureshi O.S., Hewison M., Walker L.S., Lammas D.A., Raza K., Sansom D.M. 1, 25-Dihydroxyvitamin D3 and IL-2 combine to inhibit T cell production of inflammatory cytokines and promote development of regulatory T cells expressing CTLA-4 and FoxP3. J. Immunol. 2009;183(9):5458–5467.
Shakoor H, Feehan J, Al Dhaheri AS, Ali HI, Platat C, Ismail LC, Apostolopoulos V, Stojanovska L. Immune-boosting role of vitamins D, C, E, zinc, selenium and omega-3 fatty acids: Could they help against COVID-19? Maturitas 2021;143:1-9. doi: 10.1016/j.maturitas.2020.08.003.
Ran L, Zhao W, Wang H, Zhao Y, Bu H. Vitamin C as a Supplementary Therapy in Relieving Symptoms of the Common Cold: A Meta-Analysis of 10 Randomized Controlled Trials. Biomed Res Int 2020;2020:8573742. doi: 10.1155/2020/8573742.
te Velthuis AJ, van den Worm SH, Sims AC, Baric RS, Snijder EJ, van Hemert MJ. Zn2+ inhibits Coronavirus and ARTERIVIRUS RNA POLYMERASE activity in vitro and Zinc ionophores block the replication of these viruses in cell culture. PLoS Pathogens 2010;6. doi:10.1371/journal.ppat.1001176.
Hemila H. Zinc lozenges and the common cold: a meta-analysis comparing zinc acetate and zinc gluconate, and the role of zinc dosage. JRSM Open 2017;8(5):2054270417694291. doi: 10.1177/2054270417694291.
Wu D, Meydani SN. Vitamin E, immune function, and protection against infection. Vitamin E in Human Health 2019:371–84. doi:10.1007/978-3-030-05315-4_26.
Kieliszek M, Lipinski B. Selenium supplementation in the prevention of coronavirus infections (COVID-19). Med Hypotheses 2020;143:109878. doi: 10.1016/j.mehy.2020.109878.
