Yes it can, but be skeptical of supplements making these claims because there’s no single food or nutrient that will magically boost immunity. For example, Echinacea, a very popular herb (in the daisy family) taken to combat colds does not have research to support cold/flu/virus prevention when tested against a placebo. In most studies, Echinacea also didn’t lessen symptoms for those who got sick. However, don’t be discouraged; there are other ways you can keep our immune system strong to prevent catching a cold or recover faster if you do.
 1. Food before supplements
Skip the million of vitamin supplements and instead load up on the fruits and veggies. A nutritionally-diverse diet emphasizing fruits and veggies appears to be beneficial. Research has compared people eating either their normal diets (averaging two to three servings of fruits and veggies) versus a diet to including at least five plus servings of fruits and vegetables each day. The higher fruit-and-vegetable groups have repeatedly shown to have a better immune response than the people who didn’t up their produce intake. Important nutrients to focus on are protein, zinc and vitamins A, C and E are important.
Examples of foods that have these nutrients are:
- Protein: fish, legumes (beans, peas and lentils), lean meat or poultry, tofu, nuts and seeds, eggs, and milk and milk products
- Zinc: lean meat and poultry, fish, whole grains, legumes, nuts and seeds
- Vitamin A: dark green or orange vegetables, red, yellow and green sweet peppers, sweet potatoes, and winter squash. These are good sources of carotenoids, which our bodies convert to Vitamin A. Preformed vitamin A is found in fatty fish and fortified foods like milk and soy beverage.
- Vitamin C: kiwis, oranges, red, yellow and green sweet peppers, guava, broccoli, strawberries, and Brussels sprouts
- Vitamin E: nuts and seeds, nut and seed butters, avocadoes, fish, vegetable oils, and leafy green vegetables
Besides vitamins and minerals, also consider what is happening with your good gut bacteria. There’s significant evidence to suggest that there is a connection between your gut and immune system. Increasing the amount and variety of good bacteria in your gut directly enhances your immunity. Add more foods like sauerkraut, kimchi, miso, kombucha, plain yogurt and kefir.
2. Manage your stress
People who manage stress better and have a more positive emotions are much less likely to become sick than those with chronically elevated stress levels. Cortisol (stress hormone) can wreak havoc and suppress your immune system. Research suggests that people are five times more likely to develop a cold or virus if they have significant stress in their life persisting for a month or more.
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3. Keep Moving
The key is to get moving almost daily. To be immunologically fit, you need to be physically fit. Exercise gets white blood cells (important for the immune system) moving by increasing your blood flow, so they can do their surveillance jobs and seek and destroy in other parts of the body. Get some physical active in some way every day whether its a CrossFit class or doing yoga or going on a walk outdoors.
4. Take your Vitamin D
People with higher vitamin D levels have a lower risk of upper respiratory infections. Vitamin D has been shown to increase the production of proteins that act as natural antibiotics. We recommend clients take a vitamin D supplement, especially during winter months in Canada.  We also do not receive adequate amounts of vitamin D through our diets. Speak with one of our Dietitians if you’re uncertain about dosage of specific vitamins or mineral supplements.
5. Sleep
Less sleep can increase cortisol and cause other immune dampening effects on the body. Â Based on when you are getting up in the morning be sure to determine an appropriate time to hit the hay to get enough shut eye!
6. Skip the alcohol
Forget boozing through the period where colds and viruses are common, because heavy drinking also depletes our immune cells. Some studies have suggested that the first-line-of-defence (macrophages) are not as effective in people who have had a lot of alcohol. And there’s been suggestions that high alcohol consumption can lead to a reduction of the lymphocytes as well. So if the bug gets into you, you’re not going to be as good at containing and fighting it off.
SUMMARY & ACTION STEPS:
- Consider adding in vitamin D and probiotics as a presentative measureÂ
- Avoid exposure to those that are sickÂ
- Focus on stress management and getting loads of sleepÂ
- Drink enough fluid
- Get extra fresh fruit and vegetables into your dietÂ
- Continue exercising regularlyÂ
- Limit alcohol consumptionÂ
Looking for more guidance and help? Book a FREE nutrition consultation HERE.
Blog written by:
Alysha Coughler
Food for 6S Registered Dietitian, Sports Dietitian, PTS
References:
(1) Martineau AR, et al.. Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data. BMJ. (2017)
(2) Aglipay M, et al. Effect of High-Dose vs Standard-Dose Wintertime Vitamin D Supplementation on Viral Upper Respiratory Tract Infections in Young Healthy Children. JAMA. (2017)
(3) Meng H, et al. Consumption of Bifidobacterium animalis subsp. lactis BB-12 impacts upper respiratory tract infection and the function of NK and T cells in healthy adults. Mol Nutr Food Res. (2016)
(4) Braga VL, et al. What do Cochrane systematic reviews say about probiotics as preventive interventions?. Sao Paulo Med J. (2017)
​(5) Wang Y, et al. Probiotics for prevention and treatment of respiratory tract infections in children: A systematic review and meta-analysis of randomized controlled trials. Medicine (Baltimore). (2016)
