The immune system

The body faces numerous assaults throughout the year, athletes during intense training sessions, non-athletes during the late autumn with weather changes. All of this can be anticipated. Therefore, I will explain the role of the immune system, how assaults work, and most importantly, how to strengthen the immune system with dietary advice to achieve the perfect balance between prevention and health.

Training and damage of the immune system

Intense training can create a lot of changes regarding the organism and some parameters of the immune system. A lot of these changes are due to the hormonal response and the athlete’s profile. In this population, we often see on food balance sheet, inappropriate supplies of energy and essential micro nutrients regarding the needs like Omega 3 fatty acids, zinc, copper, calcium, A, B6, B9, B12, C, D and E vitamins… All of them involved in the good functioning of the immune system. These deficiencies can impact the regulation of the immune system, especially if they are numerous and non isolated! I therefore guide you towards an adapted alimentation by proposing at the end of this article a non exhaustive list of better food sources, permitting you to create on your own your « natural immune system » menus.

C vitamin : better winter protection

A rich in C vitamin alimentation can have a good impact on athletes who are often touched by upper respiratory infections (URI) and who train in a hard and intense manner. The harder the training is, the greater is the risk for the athletes to be touched by URI. However, moderate training stimulates the immune functions whereas an intense physical period (running an ultra, Ironman…) provokes a transitional weakness of the first line of defence against infections. Then, a few weeks after the intense effort, the URI are more likely to happen. It is proven that the ingestion of some food and eventually some C and E vitamins and carbohydrates (glucose, fructose, maltodextrine, starch…) before, during and after an intense training, has the ability to boost the immune mechanisms in order to limit these kind of infections.

Note: Other factors like stress, lack of sleep, mental fatigue, weak nutritional supplies or weight loss can affect the immune system.

Probiotics : a health ally…

Probiotics, living micro organisms (most of the time bacteria), taken in sufficient quantities, can have a great impact as it improves the intestinal flora balance. The intestine is known as the « second brain of the human body ». Probiotics have a real interest regarding infectious diarrheas, the intolerance to lactose and to gluten, it helps the intestinal transit and some immune tags. Having an intense physical activity (especially running, trail, triathlon…) can create gastrointestinal disorders. As we now know the qualities of probiotics, it seems interesting to include them into the athlete’s diet. They are found in yogurts and in fermented milks.

Note: As a supplement of these probiotics, it’s interesting to add non digestible prebiotics that are beneficial to the host by stimulating selectively the growth or the activity of some colon bacteria. Prebioctics are found in fresh fruits and vegetables: artichoke, asparagus, beetroot, banana, strawberry, chicory, flax, garlic, onion, honey, leek and cereals like rye and barley.

Ginseng : a great root

Ginseng is known as a plant that favours a better resistance to respiratory infections and stimulates the immune activity. It’s therefore interesting to think about taking some as a supplement during training periods or even for an upcoming competition.

Food sources

Practical information: Main food sources of essential micro nutrients for your immune system that can help you realise by yourself your menus:

• A Vitamin: Fish liver, egg yolk, butter, fat dairies (cheese, sour cream, whole milk..), poultry liver and meat;
• A Provitamin: fruits and vegetables (carrots, watercress, cabbage, spinach, fennel…);
• C Vitamin : fruits (citrus fruits like orange, lemon…, kiwi, exotic fruits, acid berries : blackcurrant, red fruits….), green vegetables (cabbage…);
• D Vitamin : cod liver oil, fat fished (sardine, herring…), fish livers, egg yolk + « sun exposition »;
• E Vitamin: plant oils (olive, colza), oilseed proteins (almonds, hazelnuts, nuts…), wheat germs, eggs, butter, fruits and vegetables (avocado, tomato, spinach, brocoli…);
• B6 Vitamin : meats and fished, offal, wheat germs, yeast, whole cereals and whole cereals products, leguminous (beans, lentils…), banana;
• B9 Vitamin: offal (liver…), meat, green vegetables (spinach, cauliflower…), leguminous (beans, peas…), cereal germs, whole cereals and whole cereal products (pasta, bread…);
• B12 Vitamin : Offal (liver…), fishes, meats, cheeses, seashells (oysters…).

As a conclusion

Do not forget that a diverse alimentation that includes seasonal products and avoids transformed mass production issued products is the key to your health! Answering positively your needs will optimise your efficiency, limit your weak moments and improve your performances!

Sportingly,

Nicolas AUBINEAU
Sports Dietitian Nutritionist