Immune system of athletes (Part five)

Amino acids are best known for their central function as a building block of the numerous proteins. They are essential for a functioning immune system and are needed for the synthesis of muscles and the structure of the skin. They are components of enzymes, hormones, DNA or act as important signal substances of the brain.

Amino acids can be divided into two categories: essential and non-essential amino acids. The first one, has to be taken in through food, since our body cannot produce them itself. In contrast, the non-essential amino acids can be produced by the body itself if sufficient amounts of nitrogen are available. A very unbalanced diet can lead to deficiencies in individual amino acids, because not all amino acids are present in all dietary proteins. Accordingly, a varied diet is of great importance, because only in this way can the need for all amino acids be met.

L-arginine and L-ornithine

L-arginine is the precursor of L-ornithine. L-arginine is involved in the release of various hormones. For example, growth hormones, insulin and noradrenaline. Furthermore, it is an important factor in the cellular immune response and is involved in the formation of collagen and in this context is important for wound healing and bone metabolism. 

In addition, L-arginine is the precursor of nitric oxide (NO), which plays a central role in the regulation of vascular tone (acts as a vasodilator).

Recommended daily intake

  • Women/men: 2 - 6 g

Occurrence in 100 g:

  • Peanuts: 3.5 g
  • Shrimp: 1.2 g
  • Chicken breast: 1.5 g
  • Oatmeal: 0.9 g
  • Chicken egg: 0.9 g

L-glutamine and L-glutamic acid

L-glutamic acid is a non-essential amino acid that the organism can produce in sufficient quantities from various precursors. Glutamic acid itself serves as a precursor for L-glutamine.

L-glutamine is a nitrogen supplier for the synthesis of many important DNA building blocks. Furthermore, L-glutamine is an important source of energy for cells of the immune system and for many tissues of the body.

In addition, L-glutamine itself is a messenger of the central nervous system (neurotransmitter).

Recommended daily intake

  • Women/men: 2 - 10 g

Occurrence in 100 g:

  • Parmesan cheese: 8.1 g 
  • Chicken breast: 4.1 g
  • Oatmeal: 3.1 g
  • Chicken egg: 1.8 g
  • Whole milk: 0.8 g


Lysine is an essential amino acid that must be consumed in sufficient quantities with food. A deficiency of L-lysine leads to growth disorders and reduced immune function. Accordingly, L-lysine plays an important role in immune function and has an antiviral effect. The most important function of L-lysine is bone metabolism (stimulates osteoblast activity).

Recommended daily intake

  • Women/men: 38 mg/kg body weight

Occurrence in 100 g:

  • Parmesan cheese: 3.0 g 
  • Tuna: 2.2 g 
  • Pork, fillet: 2.2 g 
  • Soybeans: 1.9 g 
  • Oatmeal: 0.5 g


Burgerstein, U. P., Schurgast, H. & Zimmermann, M. (2012). Handbuch Nährstoffe. 12. Aufl. Verlag: Trias.1.

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