The two most important dietary for tired athletes are energy and carbohydrate intake, but other nutrients can also help to prevent chronic fatigue in athletes.
Protein is one nutrient that athletes tend to favour. Because there is a link between protein malnutrition and immune system depression, it may be a good idea to check if you are getting sufficient protein in your diet. A depressed immune system will make an athlete more susceptible to infections, particularly of the respiratory tract and this can lead to chronic fatigue.
Research results indicate that athletes who participate in resistance and/or endurance training need 1,3 to 1,8 g of protein per kg of body weight on a daily basis.
A 70 kg athlete would, therefore, need to eat between 91 and 126 g of protein per day. Interestingly enough studies have found that athletes who train at high altitudes need even more protein, namely 2,2 g per kg body mass per day.
A 70 kg athlete would thus need 154 g of protein a day when training at altitude. A 100 g portion of meat or fish provides about 25 g of protein, an egg about 7 g of protein and a 300 ml glass of milk about 10 g of protein.
All these high-protein foods also contain quite a lot of fat, so if you are protein-loading take care to reduce your fat intake (see below) and to use low-fat milk and dairy products, lean meat and fish and not to add too much fat during food preparation.
Researchers are at present not sure if athletes should increase their fat intake to improve endurance and boost their immune systems, or not.
Until we have greater clarity about the role of fat in the diet of high performance athletes, it is safe to obtain about 35% of energy from fat. This translates to about 80 g of fat per day for an athlete who uses 8 400 kJ. Five tablespoons of polyunsaturated margarine or cold-pressed oil or salad dressing will supply 80 g of fat to the diet. As mentioned above, high protein intakes will also provide considerable quantities of fat to the diet and must be taken into consideration when you are calculating your fat intake.
Exhaustive exercise causes a great deal of oxidative stress in the human body resulting in the formation of free radicals which can depress the immune system and contribute to chronic fatigue. Studies indicate that certain antioxidant vitamins can assist athletes to avoid chronic fatigue.
The following vitamins are powerful antioxidants and athletes can benefit from increasing their intake as follows:
- Vitamin C - rich sources are oranges, grapefruit, lemons, naartjies, pawpaw, spanspek, strawberries, guavas, Kiwi fruit, cabbage, cauliflower, broccoli, green peppers;
- Beta-carotene - best sources are yellow peaches, pawpaw, mangoes, spanspek, carrots, pumpkin, sweet potatoes, butternut;
- Vitamin E - cold pressed vegetable oils (wheat germ oil, cottonseed oil, avocado oil), leafy green vegetables (spinach), whole-grain cereals, liver and eggs.
Athletes should attempt to obtain these antioxidant vitamins from foods whenever possible, especially vitamin C and beta-carotene (the precursor of vitamin A).
There are, however, some indications that the population in general does not obtain sufficient vitamin E to meet increased needs, so that athletes who definitely have an increased requirement, may have to take vitamin E supplements.
New avenues of research have found that certain plant compounds which are called plant sterols and sterolins, have a positive effect on the human immune system.
Athletes suffering from chronic fatigue may find it helpful to take plant sterol supplements.
It is, however, important not to overdose on any supplement as this can also have negative effects on health.
Taking too much vitamin A can cause a number of potentially harmful side-effects such as flaky skin and liver damage. Always make sure that you take vitamin and mineral supplements as prescribed. Don’t fall into the trap of thinking that if a small amount (1 tablet/sachet) of a supplement a day does you good, then taking more will have even better results.
Vitamins and minerals are beneficial as long as you take them in moderation.
Hopefully these diet tips will help all of you who exercise intensively, to prevent chronic fatigue. - Dr I V van Heerden, D.Sc.