Eating To Support Your Immune System

Immunity is on everyone’s mind right now as the world grapples with COVID-19. Many of us are taking more precautions than usual including washing our hands more often, working from home and practicing good respiratory hygiene. 

While there’s no known cure for COVID-19, maintaining a healthy diet can help support your immune system during this stressful time. The nutrition tips below are by no means a replacement for the WHO and CDC recommendations, but instead, a few add-ons to nourish your natural defenses.

Probiotics

The gut microbiome forms a protective layer between our bloodstream and the outside world, and plays an important role in regulating immune function and inflammation. Studies suggest that taking probiotics may help shorten the duration of respiratory illnesses in some people [1]. Although the right dosage and bacterial strains are still being determined, incorporating a probiotic supplement and/or probiotic-rich foods may offer immune benefits. 

Ideas: Food sources of probiotics include yogurt, kefir, kombucha, sauerkraut, and kimchi. For something different try this Yogurt Parfait with Pistachio Oil and Apricot Compote.

Vitamin D

Vitamin D can be synthesized by our bodies from cholesterol and exposure to the sun, however, many of us run low after winter. Vitamin D is involved in various immune pathways, and some studies suggest daily or weekly supplementation of vitamin D may help protect against respiratory tract infections, especially among those with low baseline levels [2].

Ideas: Vitamin D is relatively hard to find in food, however, salmon, sardines, swordfish, tuna, and vitamin-D fortified dairy products like yogurt and milk are all decent sources of the ‘sunshine vitamin’. Try this Roasted Salmon Sheet Pan Dinner to help you meet your daily vitamin D needs.

Vitamin C

Vitamin C has long been associated with immune function but for most people, it appears to be more helpful for shortening the duration of cold symptoms, rather than preventing colds altogether [3]. In addition, vitamin C is an antioxidant vitamin and may help off defend against free-radical damage associated with pollution, smoking, alcohol, stress, etc. 

Ideas: Vitamin C is found in a wide variety of foods, particularly fruits and veggies. Aim for ½ a plate of vegetables and three colors at every meal. This salad is packed with vitamin C-rich ingredients like oranges, jicama, and avocado.

Zinc

Zinc is important for normal immune function and low zinc levels can make you more susceptible to illness. Furthermore, some studies suggest that zinc may be helpful for reducing the duration of cold-like symptoms [4]. Vegetarians and vegan are particularly susceptible to low zinc. Although zinc can be found in plant-based foods, it tends to be less bioavailable than zinc from animal sources because of the presence of phytates. 

Ideas: Long-term zinc supplementation can lead to copper deficiency and is generally not advised. Aim to incorporate a couple of zinc-rich foods throughout the week such as oysters, crab, pork chops, chicken, yogurt, beans, almonds, pumpkin seeds, and cashews. Soaking or sprouting nuts and legumes may improve the bioavailability of zinc from plant-based sources. Try this easy Crab Cake recipe to boost your zinc intake.

Probiotics, vitamin D, vitamin C, and zinc can be helpful for maintaining a healthy immune system, but don’t lose sight of the bigger picture. Follow the CDC/ WHO guidelines; eat a wide variety of whole foods especially colors; get adequate sleep and regular exercise, and manage your stress to minimize your risk and strengthen your immune defenses.

Edwina Clark, MS, RD, APD (Aus), CSSD

Edwina is a nationally-recognized dietitian and wellness expert, dually credentialed in Australia and the US. She has worked for several early-stage businesses as a nutrition consultant, content creator, and brand spokesperson, and has been featured on sites such as TIME, Women’s Health, SELF, and Shape, among others. In her free time, you can find Edwina blogging on edwinaclark.com, running, and planning her next travel adventure.

References:

[1] King S, Glanville J, Sanders ME, Fitzgerald A, Varley D. Effectiveness of probiotics on the duration of illness in healthy children and adults who develop common acute respiratory infectious conditions: a systematic review and meta-analysis. Br J Nutr. 2014;112(1):41–54. doi:10.1017/S0007114514000075

[2] Martineau AR, Jolliffe DA, Hooper RL, et al. Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data. BMJ. 2017;356:i6583. Published 2017 Feb 15. doi:10.1136/bmj.i6583

[3] Hemilä H, Chalker E. Vitamin C for preventing and treating the common cold. Cochrane Database Syst Rev. 2013;(1):CD000980. Published 2013 Jan 31. doi:10.1002/14651858.CD000980.pub4

[4] Singh M, Das RR. Zinc for the common cold. Cochrane Database Syst Rev. 2013;(6):CD001364. Published 2013 Jun 18. doi:10.1002/14651858.CD001364.pub4

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