Eating for Immunity: Ideas to help you stay well this winter

Eating for Immunity: Ideas to help you stay well this winter

Now that the colder months are upon us, it’s time to be proactive with our nutrition for the best immune system defence. 

For active people, immune function plays a role not only in fighting off infections but also in promoting tissue repair to recover from exercise and injury. To function properly, the immune system requires lots of nutrients – both macro and micronutrients. 

For a triathlete under a heavy training load, requirements are even higher - putting you at risk of a suppressed immune system if you’re not meeting your needs.

To help you stay well over the colder months, I’ve put together a few key points to keep you firing on all cylinders this winter!

1. Rest and Recovery is Key

• Moderate training loads can support the immune system
• Heavy training loads, particularly with high-intensity sessions, can compromise the immune system
• Immune system down for 72 hours following high-intensity training making you more susceptible (especially to bacteria on the roads)
• Don’t want to see big spikes in the training load – slow and steady increase in TSB
• Rest and recovery are key 

2. Avoid Low Energy Availability

• Energy availability is the amount of energy left in the body once energy is expended on exercise
• That energy availability is what’s left to support regular body functions like your immune response
• Endurance athletes need to ensure their energy intake is greater than their energy expenditure
• You can’t eat the same thing each day unless your training is exactly the same
• Support your immune system by scaling up on heavier training days

3. Carbohydrate is Protective

• Training in a carbohydrate-depleted state, or not refuelling properly can be a contributing factor to impaired immunity
• After sustained exercise, there’s an automatic release of stress hormones
• These hormones in excess (think cortisol) suppress the body’s immune response immediately following a training session, leaving us susceptible to infectious agents²
• Ensuring we have enough carbohydrates in our diet to support the demands of training, we can blunt the release of stress hormones and reduce the stress placed on the immune system²
• If you are unsure of your individual carbohydrate requirements, meet with a Sports Dietitian to calculate the correct amount and timing for your training schedule 

4. Gut Health

• 70% of immune cells reside within the gut
• Front line – intestinal wall. Acts as a physical barrier to foreign invaders (think the bouncer)
• Second-line – a more sophisticated immune system made up of cells, tissues and organs (think alarm, security cameras etc)
• Delicate balance of fending off the bad and balancing the good microbes
• Imbalance can lead to auto-immune disease or immune-compromised
• How to keep your gut microbes happy:

          - Fibre

          - Prebiotic foods – foods that feed our microbes:

                   < inulin, FOS + GOS – nectarines, chickpeas,  almonds, asparagus, grapefruit

          - Probiotic foods – yoghurt, miso, tempeh, sourdough
 

5. Eat the Rainbow

• Consume a wide variety of fruit and vegetables to ensure you’re getting all the right vitamins and minerals
• Iron, zinc^1,2, Vitamin C & D
• Athletes with even mild deficiencies in any of these micronutrients can have an altered immune response¹

Like everything else, there’s no magic pill to improve your immunity. Plan rest days and some lighter training weeks, eat a variety of fruit and vegetables and ensure you’re meeting your energy and carbohydrate requirements. Sleep well, wash your hands before eating and stay well this winter.

To delve deeper, take a listen to my recent Triathlon Nutrition Academy Podcast, Episode 44: Eating for Immunity

References

1. Burke, L., & Deakin, V. (2015). Clinical Sports Nutrition (5^th ed.). North Ryde, NSW: McGraw-Hill.
2. Gleeson, M., Nieman, D., & Pedersen, B. (2004). Exercise, nutrition and immune function. Journal of Sports Sciences, 22(1), 115–125. doi:10.1080/0264041031000140590
3. Seher Çağdaş Şenişik. (2015). Exercise and the immune system. Turkish Journal of Sports Medicine, 50 (1), 11–20. 
4. Nutrition and the Immune System. (2018). Nutrition Health Review. 118(1), p13. 

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