Athletes who push their bodies to the limit are at a higher risk of illness and infections, writes performance nutritionist Mhairi Keil
It’s an unfortunate fact that athletes who train hard are at a higher risk of upper respiratory tract infections than those who are moderately active or sedentary individuals.
Factors that increase an athlete’s susceptibility to infection include:
- An inadequate diet: low energy and nutrient intake, poor recovery nutrition practice and dehydration
- Increased exposure to bugs, due to increased breathing rate and frequency
- Environmental conditions such as cold weather, altitude
- Psychological/emotional stress
- Intense training
- Lack of sleep
Alone or together, these factors can result in a suppression in immune function, increasing susceptibility to infection, which can also increase the risk of injury, or at least cause under-performance. Persistent illnesses and infections are not only frustrating, but also disruptive to training targets, body composition goals and, ultimately, competitive performances. There is a well-established role for nutrition in supporting the immune function and the key is prevention.
After intense training sessions functionality of certain immune cells is reduced. Carbohydrates are one of the major nutrients that have been shown to help minimise this suppression in immune function, helping to reduce the risk of illness.
Post-training recovery snacks that contain a good source of carbohydrates, either in the form of sports recovery drinks, flavoured milks, home-made pasta, rice or noodle dishes, sandwiches and wraps, or fruit, dried fruit and yoghurt, consumed as soon as possible or within 20 minutes after training, are vitally important.
High-quality proteins, found in dairy, lean meat, fish, eggs, or vegetarian sources, such as soy products (edamame beans, tofu, soy-based yoghurts or protein shakes), are essential to help with the production of new immune cells. Consuming small quantities at regular intervals throughout the day will be beneficial.
A diet that is rich in polyphenols – nutrients that have antioxidant properties – will help to minimise oxidative damage caused by high-intensity training and support the immune system. Such foods include: bright red, orange and green fruit and vegetables such as berries, cherries, pomegranate, broccoli, spinach, red peppers, sweet potato and butternut squash, foods rich in vitamin A, C and E (citrus fruits, kiwis, nuts, seeds, and the previous list of fruit and vegetables), red grapes, herbs and spices, particularly curcumin found in turmeric, green tea, olives and dark chocolate.
Probiotics: A wealth of evidence shows regular consumption of probiotics can help modify the immune response and reduce the incidence of infections. Probiotics sources include yoghurts, drinking yoghurt and probiotic drinks such as Yakult and Actimel.
Omega-3 fatty acids: These essential fatty acids play an important role in immune function, but are also integral to joint, brain and heart health. Food sources include oily ﬁ sh (mackerel, salmon, sardines), walnuts and seeds.
Vitamin D: This vitamin is produced by cells in the skin in response to UVB rays from the sun. Vitamin D insufficiency and deficiency are common in athletic and non-athletic populations in the UK and it has been shown to reduce immune function, as well as impact on bone health and muscle function.
Dietary sources of this nutrient are minimal, but include oily fish, eggs, fortified products such as margarine and cereals. These products may only account for up to 10% of our daily vitamin D requirements, therefore a low-dose vitamin D supplement is worth consideration. By consuming a healthy and balanced diet that meets an individual’s energy requirements and paying attention to food quality and nutrient timings, athletes can take a proactive approach to reducing the risk of illnesses and minimising disruptions to training and competition goals.