January has been and gone, but those pesky winter bugs are still hanging around.  For a number of reasons, this time of year is one when most of us have to work that little bit harder to stay healthy; the repercussions of burning the candle over the festive season, lack of daylight and vitamin D (more on this later), your sniffly work colleagues and as an athlete starting to ramp up the training for the season ahead, your body is under more stress.  Yes, exercise is a form of stress! And, as in many scenarios when you need to throw things out of balance to achieve great things, the conditions need to be right for you to reap the benefits.

What do I mean by that? A strong immune system is important for fighting off colds, flu and infections, but also for being able to recover properly from training and in turn see results from the hard work you put in.  It’s about getting the balance right; there’s lots of research to suggest that exercise itself benefits the immune system.  But, remember, stress is cumulative, so even if you don’t think you’re training that hard, being busy at work, dealing with emotional stress, scrimping on sleep can all impact on your system as a whole and throw things out of kilter – cue sore throats, lack of motivation, lethargy, the list goes on.  You don’t have to be laden in bed to be experiencing immune suppression.

What is the immune system? And, why is it so important?

A lot more complex than meets the eye, the immune system is made up of several synergistic segments, which are constantly responding to our internal and external environment.

  • Physical barriers: saliva, tears, the respiratory tract, the gastrointestinal tract
  • Innate immunity: the first line of defence – bleeding, inflammation and acute pain you experience immediately when you hurt yourself
  • Adaptive immunity: the immune response with memory! We become immune to certain pathogens by acquiring that immunity from previous exposure (think of those nasty childhood illnesses – chicken pox, measles, mumps)

These segments constantly talk to each other, making sure when one hasn’t been able to fix the problem, another can jump in and offer a helping hand. In it’s entirety, the immune system protects us from infectious substances, it’s integral in healing and repair and it’s self regulating, meaning it responds at just the right level required to deal with the task in hand.  When it’s over or under stimulated, you can run in to problems.

This is where the T regulatory cells come in – it’s their job to shut down the immune reaction at the end of a response, bringing your body back into a healthy balance.  So, keeping these guys happy is particularly important.

How do you maintain a healthy, balanced immune system?

  • Look after your gut! Your T-regulatory cells live there and are responsible for 60% of your overall immunity. There is increasing evidence now to suggest the nutritional value of food is somewhat determined by the state of the gut microbiome, and likewise the food we consume shapes the microbiota that live there. If that symbiotic relationship is failing you can be putting lots of goodness in, but getting minimal gains. What steps can you take to keep your gut happy and health? Up your intake of fibre – a wide variety of fruit and vegetables, whole grains, beans, pulses, lentils, which acts as a prebiotic, creating the right environment for healthy and a wide diversity of bacteria to thrive.


  • Probiotics can be helpful, particularly when you up your training a notch. A substance called Secretory IgA – the secretory form of antibody immunoglobulin A, is released in the gut to provide protection against pathogens. It’s the first line of defence against bad bacteria, yeast, parasites and other toxins, which can lead to systemic inflammation and infections.  And, it’s commonly dampened down when your body is under stress. Saccharomyces Boulardii in particular stimulates sIgA and has been used to strengthen immune responses in athletes. 


  • Eat a balanced diet, and don’t skimp on carbs! Your body needs glucose, the metabolite of carbohydrate, to fuel your muscles and to produce energy. Therefore training in a carbohydrate depleted state is more likely to increase the amount of the stress hormone cortisol produced by your adrenals, and with it an increase in inflammatory cytokines, which trigger immune responses in the body.  Eat something small before exercising and within 30 minutes after to dampen that stress response – oatcakes and nut butter, a banana.  And, be sure to eat a good balanced meal within 90 minutes of a workout.  Training on empty consistently can lead to burnout – chronic inflammation, illness and injury.


  • Oats in particular are an under-rated ‘super food’, made up of beta-glucans, a soluble fibre known for immune boosting properties. The Japanese have been using them as a natural treatment for decades, research indicating that they up-regulate communication between different strands of the immune system, making for a stronger team! It’s worth noting that the body doesn’t produce beta-glucans – they need to come from your diet if you want to reap the benefits! You can read more about the health benefits of oats here.


  • Eat the rainbow (aim for 8-10 a day). Yes, the Government guidelines previously suggested 5 was enough….however, those guidelines were set over 20 years ago (!!) and recently have been doubled.  Endurance athletes need to pay more attention than most to their fruit and vegetable intake, due to the stress they put their bodies under.  The harder you train, the greater the demand for micronutrients.  As well as providing fibre, which keeps you fuller for longer and keeps your digestive function healthy, below are just some of the nutrients you should be looking out for. Although simply by aiming for a variety of colour and 8-10 a day, you’ll already be on to a winner!


  • Vitamins A, C & E: antioxidant nutrients acting to prevent oxidative damage, which occurs as a result of free radical formation (this occurs with prolonged physical activity, so common place in endurance athletes).   Vitamin C is also integral in collagen formation, which is crucial for healing of tissues and tendons, and Vitamin A is a precursor to formation of sIgA, which we know is important in immune support.  Foods rich in vitamin C include citrus fruits, broccoli and leafy greens, berries; Vitamin E you can get from almonds, spinach, avocado, sunflower seeds; There are 2 types of vitamin A – pre-formed found in animal products and pro-vitamin A carotenoids found in fruit and veg– butternut squash, carrots, sweet potatoes.


  • Vitamin D: particularly important for keeping your regulatory T cells healthy and balancing out the immune system.  It’s also a key nutrient in maintaining healthy bones and in turn production of red blood cells, which are made in the bone marrow.  We need sunlight to absorb the active form of vitamin D (cholecalciferol – vitamin D3) and given we live in Scotland, it’s not surprising most of us are depleted in our stores.  Food sources include mushrooms, oily fish, eggs.  In addition, a supplement is recommended at around 1000ius daily, particularly in the winter months.


  • Magnesium – needed for production of energy, muscle contraction and relaxation. It is a cofactor in just about every function in the body including digestion, detoxification and production of neurotransmitters such as serotonin and GABA, which are integral to sleep, mood and motivation. It also has a strong connection with immune function, deficiencies leading to inflammatory responses in the body.  Load up with plenty of green leafy vegetables, whole grains such as brown rice, quinoa, beans and pulses.


  • Folic Acid – essential for formulation of red blood cells. They carry oxygen around your body, fuelling your muscles, providing nutrients to tissues, initiating immune responses when they are required.   Unsurprisingly, dark leafy greens are also rich in folate….common pattern occurring?


  • Zinc – the research into the benefits of zinc on immunity is vast. It’s central to development and function of the cells mediating immune response.  Back to regulating the immune response, zinc supports the role of T-regulatory cells ensuring the immune response doesn’t spiral.


  • Lastly, tune into your body, it will tell you everything you need to know if you listen carefully enough. Endurance athletes in particular are used to dealing with pain, so much so, we can become desensitised! Know when to pull back and recover. Monitoring your resting heart rate is a good way of seeing where you’re at every day – if it’s raised your body is probably working a bit harder to maintain a healthy balance.


So, to summarise, your body is a complex system, with systems always working hard to keep you strong and healthy.  When you put it under stress of any kind, it becomes even more important to look after yourself.  If you’ve taken anything away from this, it’s hopefully that it’s not rocket science.  As an athlete, you need to get plenty of sleep, rest regularly and treat this as part of your training, eat 8-10 portions of fruit and veg a day, keep meals balanced – protein and carbohydrates with every meal, stay hydrated.  Your body will thank you for it!


This article was written by Sarah Ormerod, trainee nutritionist and athlete training with DeZeiner Fitness.