It’s now the time of year when runners look to target a spring marathon, for others, it will be donning the trail shoes or spikes and turning up to cross country races.

One thing that is often overlooked is how changes in season, training load and lifestyle can have a negative impact on your immune health. Now is a perfect time to get on top of this to prevent it having an adverse influence on your health and performance over the winter months.

There is a lot of evidence that demonstrates how strenuous training, if not managed well through rest, recovery and nutrition, can depress the immune system, hindering performance outcomes.


Good nutritional practices are necessary for performance and immune health; however, it is not just about what you eat but also about maintaining hydration. Good hydration should not be ignored as it encourages the production of saliva which contains IgA and is the body’s first line of defence.

Most fluid whether that be tea, juice, no added sugar squashes or even coffee in moderation, contribute towards your fluid intake.

It is also worth noting that if you train indoors on a treadmill through the winter months, you may find using an electrolyte drink a useful way to keep on top of losses, as the salts help to draw fluid into the body.

With so many mixed messages around nutrition, it can be confusing to know what is right and what needs to be avoided or at least consumed in moderation. It is also important to highlight that a lot of the mixed messages around nutrition are related to general health, rather than specifically for those of us who are moderately or very physically active.

With this in mind, it is vital to consume a sufficient number of carbohydrates throughout the day, particularly in high intensity or higher volume training blocks. This not only ensures appropriate fuelling for the body but also helps to prevent the suppression of the immune system, which can be a result of inadequate nutrition.

As a general rule of thumb recommendation, aim for a third of a plate at every meal of wholegrain nutrient dense carbohydrates such as sweet potato, pasta, rice etc. on training days and a quarter plate on non-training days.

Depending on training load and individual goals, you may also require additional carb based snacks such as oatcakes with peanut butter; toast with mashed avocado or Greek yoghurt, fruit and honey.

In addition to fuelling the body, these whole grains along with beans and pulses are prebiotics; these are nutrients necessary for the correct action of probiotics to encourage a positive environment for gut flora to thrive, helping to boost immune health.

Studies have demonstrated that in times of high training or competition there is evidence in taking a 12-week course of high strength probiotics; this process has shown to prevent the incidence of upper respiratory tract infections in athletes, something they may be more prone to in heavy training.

Don’t forget that nutrition is not just about what to eat before training, it also includes what to have during longer endurance based sessions over 90 minutes and also in the immediate recovery.

Often we forget to think about fuelling during a session in training but this is equally as important as on race day. When it comes to recovery, timing and composition will be very dependent on your training plan.


Nutrition is not the only factor involved in optimising immune health and recovery; it is important to obtain sufficient sleep each night, ideally around 8 hours.

Few people know that Growth Hormone, responsible for physical repair is at its highest around 12-2am. Aiming to get to bed early enough will ensure that you make the most of this.

To minimise sleep disruption aim to turn off laptops and phones at least 30 minutes before your preferred sleep time; the blue light interferes with melatonin production – a key hormone required for quality sleep.

Try and establish some good sleep behaviours –this may include reading, having a hot drink or even listening to audio-books. By creating these protocols, and practising them daily, they become part of your preparation.

This will enable you to put them into practice wherever you are, even if you are travelling or racing away from home, ensuring that you are well rested and recovered.


The final piece to the puzzle around immune health involves regularly monitoring. This may simply be a crude measure of your resting heart rate – 5-10 beats above normal, suggest the body is either under-recovered, dehydrated or potentially coming down with an illness.

By listening to your body and making these observations, you can alter your running as required to ensure that you are not overly stressing your system and putting your body at risk.

For a more accurate measure, some runners and athletes may benefit from monitoring levels of Iron, Ferritin and B12, thyroid function, Vitamin D and WCC in the form of a blood test at regular intervals.

These biomarkers are particularly good at demonstrating how well the immune system is functioning, especially during high volume and/or intensity training blocks. With this knowledge, strategies can be implemented to ensure improved health outcomes.

One of the main challenges, especially for runners and athletes who live in region limited/lack of sunshine, is to ensure you get enough Vitamin D, therefore this is one level I would advise is regularly monitored.

Vitamin D is a very important nutrient when it comes to immune function and mood. Luckily it is very easy to supplement through the winter months.

For individuals who are highly active a serum Vitamin D level of above 75 is recommended, anything under a should be supplement required – if levels are below 50 then aim for 4000 iu (international units) a day; if levels are 50-75 then aim for 1000 iu a day.

About the Author
Renee McGregor is a Performance Dietitian and author who works with elite athletes, coaches and sport science teams to provide nutritional strategies to enhance performance and manage eating disorders.

She is the author of Training Food, Fast Fuel books and Orthorexia, when Healthy eating goes bad (Out November 2017).