What’s the latest research in Nutrition and Immunity

GSSI – Walsh, 2019

The most common question I get asked around this time of year is, “how can I not get sick?”. While most people are often looking for some elaborate response, my reply is very simple – “Reduce your stress and get more than 7 hours of sleep so that your body has the strength to resist and fight off illness”. While the answer seems basic and (to some) maybe disappointing, I’ll expound a bit on the details below and discuss some of the things that expose us to a greater risk of getting sick and basic strategies you can follow to help mitigate this risk, as reported in a large GSSI publication.

Factors that increase the risk of sickness:

  1. Fall and winter – common cold and flu season
  2. Poor hygiene and exposure to sick people
  3. Recent symptoms
  4. Air travel
  5. Poor sleep
  6. Life stress, depression, anxiety
  7. Low energy availability
  8. Increases in training load

Strategies for combatting sickness:

  1. Try to avoid sick people
  2. Ensure good hygiene and proper vaccination
  3. Avoid exposing yourself by touching eye, nose, mouth
  4. Don’t train with below the neck symptoms
  5. Manage all stress
  6. Aim for >7 hours of sleep
  7. Eat a well-balanced diet

Finally, around this time of year, supplements are always a hot topic. Everything from essential oils to supercompensation of vitamin C has been recommended for resistance to infection, but what does the research show?

  1. Zinc Lozenges (Hemilia, 2017)
    1. Zinc ions in oral lozenges inhibit rhinovirus replication and have antioxidant effects.
    1. Benefit: decrease duration of the Upper Respiratory Tract Infection (URTI) by 33%. Side effects, bad taste.
    1. Suck on Zinc Lozenges – 80mg/day which would be about 15 lozenges.
  2. Probiotics (Cox et al. 2010)
    1. These live microorganisms modulate immunity. Live microorganism administered orally for several weeks, can increase the number of beneficial bacteria in the gut.
    1. A cochrane review shows about a 50% decrease in URTI incidence and 2 day shortening of URTI. (Hao, Dong, Wu, 2015)
    1. Take 2 pills per day. Thorne FloraMend Prime has the correct strands.
  3. Vitamin D (Berry et al. 2011) (He et al. 2013)
    1. Vitamin D is an anti-inflammatory, essential fat-soluble vitamin. It influences innate immunity and has anti-inflammatory effects. Skin exposure to sunlight accounts for 90% of the source of vitamin D.
    1. Meta-analysis showed protective effects for vitamin D for URTI. Deficiency associated with longer lasting URTI in athletes. Monitoring required.
    1. Recommend 1000mg/day D3 from Thorne
  4. Vitamin C (Hemelia and Chalker, 2013)
    1. Vitamin C is a water soluble antioxidant vitamin that quenches ROS.
    1. A cochrane review of 5 studies in heavy exercisers shows about 50% decrease in URTI taking vitamin C .25-1g/day. The literature is unclear as to whether Vitamin C blunts adaptation in well-trained athletes. (Hemelia and Chalker, 2013)
    1. To stay on the food side and avoid the detrimental effects to blunting adaptations with excess vitamin C, drink 1 – 16oz bottle 100% Orange Juice.
  5. Polyphenols (Walsh, 2018)
    1. Polyphenols are anti-inflammatory, plant flavonoid, antioxidants. In vitro studies have shown strong anti-pathogenic effects following polyphenol ingestion.
    1. Meta-analysis of 14 studies show some reduction in upper respiratory infection (URTI), including during intensified training. However, there remains limited evidence for its enhanced influence on immunity.
    1. While the results of polyphenols on immunity remain unclear, increase your consumption of grapes, pistachios, cranberries, blueberries will help to boost your resveratrol intake.

So… What does this all mean…

Practical Guidelines to Maintain immunity

  1. Eat a well-balanced diet – lots of color and variety
  2. Ensure adequate protein intake (1.2-1.7g/kg/day)
  3. At the onset of cold take zinc lozenges (75mg/day)
  4. Consider taking probiotics for illness prone/travelling (greater than 10 billion bacteria/day)
  5. Consider 1000IU Vit D3
  6. Consider vitamin C for illness prone/traveling and during intense competition >200mg/day


1. Walsh, N.P. (2018). Recommendations to maintain immune health in athletes. Eur. J. Sport Sci.18:820-831.

2. Hemila, H. (2017). Zinc lozenges and the common cold: a meta-analysis comparing zinc acetate and zinc gluconate, and the role of zinc dosage. J.R. Soc. Med. Open 8:2054270417694291.

3. Hemila, H., and E. Chalker (2013). Vitamin C for preventing and treating the common cold. Cochrane Database Syst. Rev.:CD000980.

4. Cox, A.J., D.B. Pyne, P.U. Saunders, and P.A. Fricker (2010). Oral administration of the probiotic Lactobacillus fermentum VRI-003 and mucosal immunity in endurance athletes. Br. J. SportsMed. 44:222-226.

5. Berry, D.J., K. Hesketh, C. Power, and E. Hypponen (2011). Vitamin D status has a linear association with seasonal infections and lung function in British adults. Br. J. Nutr. 106:1433-1440.

6. He, C.S., X.H. Aw Yong, N.P. Walsh, and M. Gleeson (2016). Is there an optimal vitamin D status for immunity in athletes and military personnel? Exerc. Immunol. Rev. 22:42-64.

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