Elevating your immunity

Beyond vitamin C

It is winter season in South Africa, and unfortunately, winter season often means flu season for a lot of athletes and active individuals. Research has shown that strenuous bouts of prolonged exercise depresses the immune system – and what is more, inadequate and inappropriate nutrition can make the negative effects of a compromised immune system worse.

While you can’t control the weather, one thing that you have control over is your nutrition in the winter season. Several nutrients are of importance to make sure you are doing what you can to give your immune system the support it needs.

MICRONUTRIENTS

Iron

• Why it is important: Iron helps your red blood cells to carry oxygen to the rest of your body. It is also needed for the maturation and development of immune cells associated with a specific response to infection.
• Sources of iron: Meat sources of iron include red meat, liver, chicken and fish, while plant based sources include beans and lentils, fortified cereals, pumpkin seeds, tomato puree and green leafy vegetables like spinach. Make sure to include a source of vitamin C with plant-based sources to ensure maximum bio-availability.

Zinc

• Why it is important: Zinc is very important for normal development and function of cells involved in immunity such as neutrophils and natural killer cells, and a deficiency also affects the growth of other important cells involved in immune function.
• Sources of Zinc: Oysters, meat sources like chicken, beef or fish, yogurt and milk products, nuts like pecans, walnuts and almonds, and beans.

Vitamin A

• Why it is important: Interestingly enough, vitamin C steals all the limelight when it comes to immunity. But did you know that research has concluded that ”no nutritional deficiency is more consistently synergistic with infectious disease than that of vitamin A”? (Scrimshaw et al., 1968)
• Sources of vitamin A: Vitamin A is found as preformed vitamin A in foods such as liver, cod-liver oil, butter, eggs, and dairy products and as provitamin A carotenoids in foods such as spinach, carrots, and orange fruits and vegetables.

Vitamin D

• Why it is important: Vitamin D plays a role in the innate and adaptive immune responses. Vitamin D deficiency is associated with increased autoimmunity and a higher risk of infection
• Sources of vitamin D: Vitamin D made in the skin lasts about twice as long in the blood as vitamin D ingested in the diet. In the winter time we tend to get less sunlight exposure, both due to the fact that we are outside less often and wear more covering when we are outside, so be mindful to spend at least 15 minutes outside in the sun 3 – 4 times per week if you are not training outside. Food sources include fish like salmon, tuna and sardines, fortified milk, yogurt and margarine, liver, egg yolks, cheese, fortified orange juice and cereals and mushrooms.Mushrooms are the only plant food to contain vitamin D, and the amountof vitamin D varies depending on the type of mushroom as well as the amount of sunlight exposure the plant had, with maitake and portabella mushrooms boasting with the highest vitamin D content.

Vitamin E

• Why it is important: Vitamin E is a powerful antioxidant, has the ability to modulate host immune functions and plays a role in cell signalling, regulation of gene expression and other metabolic processes.
• Sources of vitamin E: Vegetable oils, nuts (especially almonds, hazelnuts and peanuts), green leafy vegetables, fortified cereals, and fruits like kiwifruit and mango.

B vitamins: vitamin B6 and B12

• Why it is important: Your body needs B6 in order to absorb vitamin B12 and to make red blood cells as well as immune system cells. Vitamin B6 is involved in the production of several neurotransmitters like serotonin, chemicals that carry signals from one nerve cell to another.
• Sources of vitamin B6: wholegrain cereals, such as oatmeal, wheat germ and brown rice, legumes like chickpeas, poultry, fish, beef, potatoes, and bananas.
• Sources of vitamin B12: B12 is found only in animal sources like liver, fish, chicken, beef, milk and milk products, and eggs. If you are a vegetarian or vegan, a supplement in oral form or injection is advised.

Vitamin C

• Why it is important: Vitamin C is an antioxidant and contributes to the immune response by supporting various cellular functions involved in immunity. Vitamin C deficiency results in impaired immunity and higher susceptibility to infections.
• Sources of vitamin C: Red peppers, oranges and orange juice, grapefruit, kiwifruit, strawberries, broccoli, cantaloupe, tomatoes, spinach and other green leafy vegetables.
• MACRONUTRIENTS

Often we just think of macronutrients in terms of the energy they provide, but did you know that they also play an important role in immune function?

Carbohydrates

• Why it is important: Consuming carbohydrate during prolonged strenuous exercise decreases the rise in stress hormones like cortisol and science has shown that it limits the degree of exercise-induced immune depression. If you are an athlete who is continually struggling with illness during hard training blocks, this might be an area that needs to be addressed. Glucose is an important fuel source for immune cells because metabolic rates of immune cells are extremely high. Evidence also suggest that carbohydrates play a role in immune recognition,
• Consuming 30-60 g carbohydrate per hour during intensive exercise during sustained intensive exercise attenuates rises in stress hormones such as cortisol and limits the immunosuppressive effects of exercise.
• Sources of carbohydrates: Focus on whole grain and low sources of carbohydrates before training and during the day (whole grain breads, pastas, brown rice, sweet potatoes etc.) and higher GI carbohydrates within hard training sessions, like a sports drink, banana, dates, or energy gels.

Protein

• Why it is important: Eating too little protein impairs immune function and leads to an increased susceptibility to infection, because the production of some important components of the immune system, depends on adequate protein availability.
• Sources of protein: Complete proteins contain all the essential amino acids (amino acids that can’t be made by the body) include animal based sources like meats (think lean beef, chicken or fish), eggs and dairy, while complete sources of protein from plants includes quinoa and soy. Plants like legumes (beans, split peas, and lentils), grains and nuts contain incomplete proteins, but eaten in combination and including enough of these foods in your diet can ensure adequate intake protein.

Fats

• Why it is important: Omega 3 fatty acids are powerful anti-inflammatory substances.
• Sources of omega 3 fatty acids: Fatty fish like salmon, sardines, and mackerel; seeds like flaxseeds. Chia seeds and hemp seeds; walnuts; canola oil; soy and soybean oil; seaweed and algae.

FINAL TIP

It is important to make sure you get these nutrients from real, whole food sources as far as possible, with the exception of vitamin B12 for vegans or in the case of a diagnosed deficiency. Not only is it better from a bioavailability standpoint, but when you eat real, whole foods you don’t just get individual nutrients – you get a whole range of other benefits like added fibre, phytochemicals and antioxidants that will ELEVATE your health, performance and immunity to the next level.

Resources

1. Gleeson, M., Nieman, DC., Pedersen, BK. 2004. Exercise, nutrition and immune function. Journal of Sports Sciences. 22(1):115-25,
2. Cobb, BA., Kasper, DL. 2005. Coming of age: carbohydrates and immunity. Eur J Immunol., 35(2):352-6.
3. Chandra, RK. 1997. Nutrition and the immune system: an introduction. American Journal of Clinical Nutrition. 66(2):460S-463S.
4. Gunzer, W., Konrad, M., Pail, E. 2012. Exercise-Induced Immunodepression in Endurance Athletes and Nutritional Intervention with Carbohydrate, Protein and Fat—What Is Possible, What Is Not? Nutrients. Sep; 4(9): 1187–1212.