Nutrition for Immune Support
Winter can be a challenging time for athletes and active individuals. The cold weather, busy schedules and increased risk of illness can make it challenging to maintain peak performance. It's a common topic of discussion during winter months at our London sports nutrition and performance clinic, and with the proper nutrition, you can help keep your immune system strong and your energy levels high. As the weather gets colder and the flu season approaches, supporting your immune system is more important than ever. Whether you're an athlete training hard or simply trying to stay healthy, a strong immune system can help you avoid getting sick.
Research shows that exercise improves immune function. However, intense exercise or sport can negatively impact your immune system. While it's great to stay active, excessive training can cause inflammation, making it harder to fight off illness. While no single nutrient or supplement can guarantee you won't get sick, specific nutrients and strategies are crucial in maintaining optimal health and immune function. By prioritising good nutrition for immune support during winter, you can help keep your immune system strong and your performance at its peak.
Underfuelling
Underfuelling, or not providing your body with the energy it needs, can impact your immune function. When you don't eat enough, your body may be deprived of essential nutrients that help your immune system fight infections. This can lead to deficiencies in vitamins and minerals, increased stress, hormone imbalances and impact your digestive system, which can negatively influence your immune system. A weakened immune system can make you more susceptible to various infections, including colds, flu, and other respiratory illnesses. It can also hinder your body's ability to recover from illness and decrease your performance. To ensure optimal immune function and athletic performance, it's essential to prioritise proper nutrition. Eating regularly, choosing nutrient-dense foods, staying hydrated, and listening to your body's hunger and fullness cues can prevent underfuelling and support your immune system. Unexpected downward trends in body mass can mean underfuelling or unplanned calorie deficits.
Antioxidants
Eat various fruits and vegetables, including the rainbow. Fruits and vegetables are packed with vitamins and minerals essential for a robust immune system.
Antioxidants, such as vitamins A, C, and E, support our immune system. By reducing inflammation caused by oxidative stress, these nutrients help our bodies fight off illness. Many antioxidant-rich foods, including fruits, vegetables, and whole grains, also contain polyphenols, which have been shown to have beneficial health properties due to their strong antioxidant and anti-inflammatory effects. While antioxidant supplements may seem appealing, excessive doses can hinder the body's natural adaptation to exercise and training. Instead, focus on consuming a diet rich in antioxidant-containing foods like whole grains, fruits, and vegetables.
Colour | Benefits | Sources |
Reds | Blood cells & anti-inflammatory | Tomatoes, strawberries, peppers, watermelon, raspberries |
Greens | Tissue healing, anti-inflammatory, muscle function, blood cells | Spinach, kale, broccoli, asparagus, kiwi |
Whites | Heart health & muscle function | Turnips, onions, garlic, pears, cauliflower |
Purples & Blues | Brain health enhances exercise adaptations | Blueberries, blackberries, purple grapes, plums, aubergine |
Orange & Yellows | Supports immune function, reduces muscle damage | Carrots, sweet potatoes, pumpkins, pineapple, mangoes |
Vitamin D
Vitamin D, a fat-soluble vitamin produced naturally by the sun, plays a crucial role in our bodies (It goes without saying that sun exposure should be done safely in line with health recommendations). Vitamin D is essential for bone strength, cell growth, calcium absorption, and immunity. A vitamin D deficiency can increase the risk of illness. The recommended daily intake for adults is 10 micrograms (400 international units). Many people may need help to get enough vitamin D from their diet, as there are only a few foods naturally rich in vitamin D. Fatty fish like salmon or mackerel, eggs, and fortified foods like orange juice and cereal are some rare sources. If you're vegetarian or vegan, you may need to consider taking a vitamin D supplement.
Omega-3 Fatty Acids
Omega-3 fatty acids are essential nutrients that our bodies cannot produce on their own. We must obtain them through our diet. Research has shown that omega-3s can benefit brain and heart health and immune function. They may also improve overall health due to their role in managing inflammation. There are three primary types of omega-3 fatty acids: EPA (eicosapentaenoic acid), DHA (docosahexaenoic acid), and ALA (alpha-linolenic acid). EPA and DHA are found in fatty fish like salmon, mackerel, and tuna. ALA is a plant-based form of omega-3s found in walnuts, chia seeds, ground flaxseed, and flaxseed oil.
Pre & Probiotics
The gut microbiome, a complex ecosystem of bacteria and fungi in your digestive tract, plays a crucial role in various bodily functions. A healthy gut microbiome is essential for overall well-being, from energy production and vitamin synthesis to protecting against pathogens and regulating the immune system. Probiotics are the beneficial bacteria that reside within your gut. A diverse microbiome, rich in probiotics, can positively impact your health. Fermented foods like kimchi, sauerkraut, Greek yoghurt, kefir, miso, cottage cheese, and kombucha are excellent sources of probiotics. To further support the good bacteria in your gut, you can also consume prebiotics, a type of fibre found in foods like oats, bananas, asparagus, garlic, and apples. Prebiotics act as food for probiotics, helping them thrive and contribute to a healthier gut microbiome.
Iron
Iron is an essential mineral found in many foods. It is crucial in various bodily functions, including oxygen transport, growth, neurological development, cellular functioning, hormone synthesis, and immune cell development. Iron deficiency can impair immune function. The recommended daily intake for iron is 8.7 mg for males and 14.8 mg for females. However, athletes, especially female athletes participating in endurance sports, may require higher amounts due to the increased demand for iron during exercise. Iron deficiency can lead to early fatigue and diminished work capacity. Iron intake can be of concern for athletes or active vegetarian and vegan athletes because of the difference in bioavailability between heme and non-heme iron. Heme iron, found in red meat, organ meats, and some seafood, is more easily absorbed by the body than non-heme iron, which is present in plant sources like leafy greens, legumes, whole grains, and seeds. For vegetarians and vegans, the recommended daily intake of iron is 1.8 times higher than for those who eat meat. To enhance the absorption of non-heme iron, consider pairing it with vitamin C-rich foods like citrus fruits, tomatoes, or peppers. By incorporating iron-rich foods into your diet, you can help ensure adequate iron intake.
Useful Tip To Increase Iron Intake
Cooking with a cast-iron skillet can add significant amounts of iron to the meals.
Zinc
Zinc is an essential nutrient that is vital in various bodily functions, including DNA synthesis, wound healing, growth and development, and cellular function. It's also essential for a healthy immune system, as it is needed to grow and develop immune cells. The recommended daily intake for zinc is 11 mg for males and 8 mg for females. Zinc is present in many foods, such as chicken, pumpkin seeds, chickpeas, cashews, yoghurt, oysters, and beef.
Tolerance & Resistance: A New Understanding
Nutrient availability plays a vital role in immune function, as both macronutrients and micronutrients are essential for many immune processes. Macronutrients provide the energy and building blocks for immune cell metabolism and protein synthesis, while micronutrients contribute to antioxidant defences.
A more recent perspective on exercise immunology suggests a shift from solely focusing on immune resistance to considering both resistance and tolerance. Where resistance refers to the strength of the immune system's weaponry, and tolerance is the ability to differentiate between harmful pathogens and harmless substances, preventing excessive or inappropriate immune responses. Contrary to previous beliefs, recent evidence indicates that immune resistance - as stated above - may not be suppressed in athletes undergoing intense training, this may suggest that nutritional supplements primarily aimed at boosting immune resistance may have limited benefits in reducing infection rates, as the immune system is already functioning adequately.
The emerging paradigm of resistance and tolerance offers a more comprehensive understanding of the factors influencing immune health in athletes. Nutritional supplements with tolerogenic effects, such as probiotics, vitamin C, and vitamin D, are now being explored as potential strategies to reduce the infection burden. These supplements may help modulate the immune response, promoting a more balanced approach emphasising resistance and tolerance.
Non-Nutritional Ways to Support Immune Function
While nutrition plays a crucial role in boosting your immune system, several non-nutritional factors can contribute to overall immune health:
Adequate Sleep: Getting enough quality sleep is essential for a robust immune system. Aim for 7-9 hours of sleep each night.
Stress Management: Chronic stress can weaken your immune system—practice stress-reduction.
Regular Exercise: Regular physical activity can help boost your immune system. Aim for at least 30 minutes of moderate-intensity exercise most days of the week.
Avoid Smoking and Excessive Alcohol Consumption: Smoking and excessive alcohol consumption can weaken your immune system.
Limit Exposure to Germs: Wash your hands frequently, avoid touching your face, and practice good hygiene to limit exposure to germs.
Avoid exercise/training with below-the neck-symptoms.
Where possible, avoid sick people
Further reading:
Walsh, N. P. (2018). Recommendations to maintain immune health in athletes. European journal of sport science, 18(6), 820-831.
Calder, P.C. (2013). Feeding the immune system. Proc. Nutr. Soc. 72:299-309.
Walsh, N.P. (2019). Nutrition and athlete immune health: new perspectives on an old paradigm.Sports Med. In press.
Sharma, S. (2021). Effect of cooking food in iron-containing cookware on increase in blood hemoglobin level and iron content of the food: A systematic review. Nepal J Epidemiol. 2021 Jun 30;11(2):994-1005.
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