Dietary supplements for athletes

Optimal results, important for burning fat, gives the full pump, effective muscle growth - if you believe the promises of relevant catalogs or companies on the Internet, you might get the idea that nothing works without sports nutrition. In particular strength athletes put in addition to an intensive training on the intake of dietary supplements.

Advertising promises a lot, but can it hold it?

How big are the side effects of expensive protein drinks, vitamin supplements, power bars and performance enhancers like carnitine or creatine? Ministries, consumer centers and scientific institutes such as the German Society for Nutrition (DGE) are in agreement: foods fortified with vitamins, trace elements and minerals are completely unnecessary for the athlete as their needs are fully covered by a balanced, healthy diet.

Nevertheless, consumers are obviously willing to spend considerable sums on expensive sports food. Also, an additional protein requirement for building muscle is falsely fooled the athletic consumers.

Are additional protein preparations really necessary?

Protein supplements represent the largest product group on the market for sports nutrition. However, since 60 to 70 percent more protein is already consumed in Germany than meets the recommendations of the DGE, this oversupply itself meets the needs of competitive athletes.

An artificially increased intake of protein therefore unnecessarily requires only the kidneys due to increased urea production. Athletes or fitness bars should actually provide the basically positive to be assessed carbohydrates for the energy supply. However, this is done primarily only by a high sugar content.

A banana consumed in between is therefore far more effective for the athlete for the subsequent supply of energy and also much cheaper.

In addition, the recommendations of the Federal Institute for Risk Assessment (BfR) with regard to the maximum levels of minerals and vitamins in food supplements should be observed in order to avoid consequential harm due to long-term overdosage.

Performance promotion through ergogenic substances

The effect of performance enhancers or ergogenic substances should be in the improvement of energy supply, proliferation of muscle tissue or prevention of sports-related cell damage. However, these modes of action are not scientifically proven.

In addition, there are sometimes serious side effects when taking these products. Caffeine is therefore enjoyed in higher doses (from six cups of coffee) even on the list of prohibited substances for the sport (doping list), with creatine inclusion in this list is still being discussed.

The ergogenic substances include:

  • creatine
  • L-carnitine
  • Various amino acids such as arginine, ornithine, glutamine or tryptophan
  • BCAA is an abbreviation for branched-chain amino acids such as valine, isoleucine and leucine
  • CLA, the conjugated linoleic acid
  • taurine
  • Herbal drugs and extracts: Guarana (active ingredient caffeine), ephedrine in the medicinal herb Ma Huang
  • Phosphate salts, alkali salts and coenzyme Q 10


Creatine is currently the most popular active ingredient that is supposed to improve performance. It is a key substance for the provision of energy in the body and consists of the amino acids arginine, glycine and methionine.

Creatine is formed in the liver, kidneys and pancreas, in muscle this substance is stored to about 95 percent. Humans require about two grams of creatine daily, of which about half is mainly from meat and fish-rich food, while the other half is formed by the body itself.

Side effects of creatine

Scientific studies have shown that after taking creatine, the concentration of this substance in the muscles increases, but at the same time increases the risk of injury to the muscles. Only at maximum short-term exposure could creatine be associated with an increase in exercise capacity. In endurance sports and submaximal loads no effect was detectable.

In addition, side effects may occur in the form of gastrointestinal disturbances and an increase in body weight of on average two kilograms due to water retention in the muscles. Since normally the body's own production (synthesis) and the supply of a well-balanced diet are sufficient for a sufficient Creatinversorgung of the body, altogether from this means is advised against.


L-carnitine consists of the amino acids lysine and methionine and is formed in the human organism in the liver, kidneys and brain. Carnitine is also not an essential substance, meaning our body can produce it ourselves. For this synthesis of L-carnitine, the vitamins C, B 6 and niacin, as well as the mineral iron are needed.

In conjunction with a balanced diet, the body is provided with sufficient carnitine even during exercise. It occurs mainly in meat, but also to a lesser extent in dairy products, eggs, vegetables, fruits and whole grains.

L-carnitine acts as a transport medium for long-chain fatty acids in the cell power plants (mitochondria). Therefore, it plays an important role in energy production from fat. However, since L-carnitine is not consumed in the transport, but can be used over and over again, scientific studies have not been able to demonstrate the alleged positive effect on performance with additional carnitine intake. Even the untrained user of this product will therefore continue to be plagued by sore muscles after an excessive effort. In contrast, only training, but not the intake of carnitine helps.

A longer-term use of this product also leads to a decrease in the body's carnitine production.

amino acids

  • arginine
  • ornithine
  • glutamine
  • tryptophan
  • BCAA: (branched-chain amino acids): valine, isoleucine, leucine

The erroneous opinion prevailing in athletes that an additional protein intake strengthens the muscle, continues even with these dietary supplements, because amino acids are the building blocks of the proteins. However, the muscle-building (anabolic) effect with a supplementation of amino acids such as arginine or ornithine could not be confirmed scientifically. There is a direct correlation between the protein synthesis and the glutamine content in the muscle. In addition, glutamine is also necessary for the immune system.

For the amino acid tryptophan an anticatabolic effect is discussed. This means that this means the muscles during intense training to protect against degradation processes and thus counteracts a central fatigue of the muscles under heavy load.

This should also be the case with the branched-chain amino acids valine, leucine and isoleucine. Although the three amino acids are essential, they are absorbed into the body through animal foods to a sufficient degree through a balanced diet.

However, scientific results on a positive effect of the amino acids on the fatigue process are not available or are contradictory with regard to tryptophan. However, protection against the breakdown of the musculature does not seem to make sense on the whole, since in the body catabolic processes (concerning the degradation metabolism) naturally exert a stimulus on anabolic (anabolic) effects.

At higher doses of an oral intake of branched chain amino acids must also be expected with gastrointestinal complaints.

Conjugated linoleic acid

This linoleic acid can be found in 16 different chemical forms, occurs mainly in the ruminal rumen of ruminants and accumulates in butter, muscle meat and milk. Animal studies show that it inhibits the growth and spread of cancer and reduces vascular changes.

In sports, this substance is said to have an antioxidant effect by acting as a preventive measure against coronary heart disease. However, the oral intake and the correct chemical structure of the conjugated linoleic acid are not yet known. It should also reduce the body fat and increase the muscle content.

So far, however, these observations have been made only on the basis of test tube or animal experiments on chicks and mice, a transferability to humans is doubtful. Since the conjugated linoleic acid is associated with growth of liver tumors at high doses, it is not recommended to take it.


Taurine is formed in the body with the help of vitamin B 6 from the amino acids methionine and cysteine ​​in the liver and brain in sufficient quantity to meet the daily needs, including an athlete. Particularly taurine-containing are tuna fish in canned meat. Dairy and vegetable foods contain little taurine. Taurine on the one hand should act as an antioxidant cell substance, on the other hand, it should have positive effects on the cardiovascular system.

In advertising, taurine is said to provide "the necessary building blocks for muscle protein" along with other amino acids, but there are no scientifically recognized studies of performance enhancement with the addition of taurine, nor is the scientifically proven antioxidant effects of this substance.

Caffeine in guarana, ephedrine in medicinal herb Ma Huang

Guarana is a name for the seeds of a South American creeper species. The caffeine contained in it has a stimulating effect on the brain and respiratory and circulatory system. The caffeine gets into the brain immediately after its admission and leads there to increased concentration ability and reaction speed. This stimulating effect lasts four to six hours.

Strong coffee drinkers, however, do not use this as a caffeine habituation begins. In the first few minutes of exercise, caffeine should increase energy production from fat. This results in long-lasting sporting stress to a saving of the body's memory for strength in the muscle, the so-called muscle glycogen. The diuretic effect of caffeine has a negative impact on the water balance during sport.

The side effects of caffeine intake can be:

  • Irritability, nervousness
  • diarrhea
  • Trembling or
  • insomnia

Ephedrine from the Chinese medicinal herb Ma Huang (Ephedra sinica) is often offered commercially in combination with caffeine and aspirin. It works by its natural amphetamines both stimulating on the circulation and weight-reducing.

Phosphate salts, alkali salts and coenzyme Q 10

Phosphate salts are components of the body's energy stores ATP (adenosine triphosphate) and KP (creatine phosphate). They are intended to increase performance in short and long distance runners and prevent lactic acid formation. However, scientific research is contradictory.

Alkali salts as chemical compounds with bicarbonate and citrate residues are said to increase the performance of sprinters and short-distance swimmers by "buffering" the resulting lactic acid. However, scientific studies have yielded contradictory results in this respect, and even had negative effects on endurance performance. Additional side effects such as stomach cramps or diarrhea were also observed.

The coenzyme Q 10 aims to improve the breakdown of carbohydrates, fats and proteins. However, scientific studies could not prove this.

Legal regulations

At present, the manufacturers of sports food products determine how their products are composed, since scientifically sound and legally binding provisions are still missing. In addition, the allocation of dietary supplements in a legal framework is confusing and problematic, because every day 20 new funds of this kind come on the market.

According to the Food and Consumer Goods Act (LMBG), foodstuffs are considered that serve to maintain life processes. This includes:

  • Proteins, fats, carbohydrates,
  • Vitamins, minerals and fiber
  • Trace elements.

Dietary supplements are also assessed according to the LMBG. They are supposed to supplement the diet when, under certain circumstances, deficiency symptoms are to be expected. Because of their health risks of misuse, however, the vitamins A and D, minerals, trace elements and amino acids are declared as additives according to the LMBG. This allows an approval only only in case of avoidance of consumer delusion and health safety. The latter should be controversial, at least for the amino acids.

The foods adapted to the particular nutritional needs of competitive athletes can be declared as dietary foods. They serve in contrast to the dietary supplements not prophylaxis, but are used only if there are already certain food-related requirements. In this group belongs a part of the mentioned Leistungssteigerer.

The German Medicines Act (AMG) assesses all substances that prevent illness or influence bodily functions. Here you will find in the sports training area many doping products, which are combated by national and international sports associations. In any case, the addition of a drug to a food is not permitted.

Expressly banned in Germany are anabolic steroids (drugs that are derived from male hormones) and prohormones (precursors of these hormones). However, the problem is that up to 20 percent of sports nutrition supplements are contaminated with undeclared prohormones and anabolic steroids, most of which are contaminated with vessels or equipment.

In particular products from Holland, USA, Russia and China are to be affected. There are some substances in sports nutrition that are in the gray area between food and medicine. These include, for example, substances such as vitamin B 6, which bodybuilders in amounts up to 50 mg (2500 percent of the daily requirement) is offered, because it should contribute to the anabolic effect of protein preparations. Creatine, taurine, CLA and L-carnitine are also substances that are on a balancing act in this regard.

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