Nutrition tip: Dietary Supplements and sports
Nutrition tip: Dietary Supplements and sports
Faster, higher, further and even better... clear goals for competitive athletes, who are often urged to take dietary supplements for their success. At the same time, the distribution of these supposedly performance-enhancing agents in popular sports is under increasing observance. How useful or promising are dietary supplements, and where is the line between supplements and doping? (Foto: ©elenathewise)

What is it?

According to regulation, dietary supplements are legally considered to be foods. As a rule, they are a concentrate of vitamins, minerals or other substances with nutrition-specific or physiological action. In sports, powdered drinks, gels, energy bars and pills are popular. Dietary supplements are not medications and do not require prescription.

From grass roots to competitive sports

Popular sport: Sport that is practised mainly in one’s free time, not to achieve national or international excellence in competitions, but for the joy of movement, physical fitness or health aspects.
Competitive sport:
Competition-oriented sport with the aim of achieving national or international excellence.

Dietary Supplements and their effects

The necessary amount of protein should basically be supplied by a normal diet. With moderate exercise, the recommendation is 0.8 – 1.2 grams per kilogram of body weight per day. Athletes can achieve this amount as part of a balanced diet. Protein powder, mostly based on milk or soy protein, is only sensible in extreme training phases for power athletes. However, an intake of more than 2 g / kg of body weight per day is not advisable and may be harmful to the liver and kidneys.

In order to prevent fatigue-related drops in blood glucose levels during endurance exercise, muscle and liver glycogen stores must be well-filled before starting and must be topped up with carbohydrates during activity. In competitive sports, supplements rich in carbohydrates, such as glucose polymer solutions (also called energy concentrates) or energy gels are sometimes recommended.

Isotonic drinks
With physical activity, the fluid requirement increases primarily because of sweating. In order to avoid dehydration during activities of longer than 60 minutes, it is important to start hydrated and to quickly replace the sweat loss orally. As a rule of thumb, drink 400 to 800 ml per hour. Rapid rehydration is possible with isotonic drinks. Ideally, one litre should contain around 80 g of sugar (glucose, sucrose, fructose, maltodextrin) and at least 400 mg of sodium (= 1 g of table salt; as a comparison, 1 level teaspoon is equivalent to 5 g of table salt). Watered down fruit juices (fruit juice spritzers), at a ratio of one part juice to one part sodium-rich mineral water, are also suitable.

Micro and macro nutrients
Potentially critical nutrients include iron (in women and vegans), magnesium and antioxidant vitamins such as B6, potassium, calcium and zinc. Deficiencies of these nutrients should be monitored by keeping a food diary (recording findings relating to insufficient nutrient supply) and by means of clinical chemical blood and urine analysis. Where necessary, nutritional deficiencies should be corrected by substitution. It makes little sense to take a “scattergun approach” when it comes to vitamin and mineral supplementation.

Ergogenic substances
These are dietary supplements that are said to have a performance-boosting effect, although this cannot be proven beyond doubt.
  • Caffein: Numerous studies have shown an increase in performance (3-6 mg/kg body weight) in endurance sports. Larger quantities and use in weight training have brought no advantage. The continued intake of caffeine in sport is usually in a concentrated form (pills, powder, ampoules, gels and carbohydrate bars).
  • Creatine: Significant increases in performance are evident in high-intensity sports (throw, jerk, jump and sprint), where a short and rapid release of strength is needed. This increase is not seen in endurance sports.
  • Buffer substances (substances that can absorb or release excess acid, so that they can be neutralised) are intended to correct an acid-alkaline imbalance and reduce associated fatigue.
  • Nitrate is intended to reduce oxygen consumption during exercise. Due to its effect on iodine transport and the formation of nitrosamine, which is carcinogenic, high doses of nitrate should be taken with caution.

Where does doping begin?

A very different problem with dietary supplements is that, in many cases, the composition is not known. Even if the composition is listed on the label, there can be no assurance that it will not contain traces of other substances (which may be on the doping list), whether intentional or unwanted (through the production process). Referring to the Cologne List (a product database) minimises the risk of unwanted intake of a doping agent -


In principle, it can be assumed that in meeting energy needs with a balanced and varied diet, the nutrient needs are met. The prerequisite for this is that the diet must be adapted to the sporting activity. Athletes who are vegan or vegetarian, or who sometimes follow a low-calorie diet for intentional weight loss, or who have food intolerances are excluded. In competitive sports, the use of some supplements may be helpful in certain situations, such as during intense training periods, competitions and overseas travel (limited food choices). Each athlete should develop an individual risk-benefit profile. Criteria for this are: type of sport, training and competition load, nutritional status and medical data.

If you would like to find out more on the topic of dietary supplements and sport, we recommend the following website:

If you have any questions, requests, suggestions or tips, please send an email to The Kornspitz® team is always happy to hear from you.

Mag. Gerda Reimann-Dorninger
Nutrition Scientist

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