D-Aspartic Acid (DAA): endurance enhancer, or non-functional supplement?

D-aspartic acid (DAA), present in the body in the form of aspartate, is an amino acid that is often presented as a way to boost energy and delay fatigue. But what does modern sports science actually say about it?

What is aspartate?

In biochemical terms it is a non-essential amino acid. That means our body can synthesise it on its own and we are not fully dependent on taking it in from food. In the body, aspartate takes part in a number of key processes, including the synthesis of pyrimidines (the building blocks of DNA and RNA) or as an intermediate in metabolic pathways.

The main promises: why do athletes take it?

Food supplements containing aspartate (often as magnesium and potassium salts) are aimed above all at endurance athletes. The main claims made include:

Mechanism of action: the fight against ammonia

The theory behind aspartate supplementation comes from its role in nitrogen metabolism. Aspartate is a precursor for intermediates of the Krebs cycle (TCA cycle), which is responsible for producing energy in cells.

It was assumed that an increased intake of aspartate might help reduce the build-up of ammonia in plasma during intense exercise. Because an elevated blood ammonia level is closely linked to the onset of fatigue, eliminating it should theoretically lead to longer and more intense performance.

What does science say? Reality vs marketing

Despite the attractive theoretical assumptions, the scientific evidence for the effectiveness of aspartate as an ergogenic aid is very weak.

Conclusion for athletes

Although aspartate is essential for metabolism to work properly, supplementing it for the purpose of increasing endurance is, according to current scientific knowledge, inefficient and ineffective.

1. Maughan RJ, Sadler DJ. (1983). The effects of oral administration of salts of aspartic acid on the metabolic response to prolonged exhausting exercise in man. Int J Sports Med, 4(2):119–123.
2. Jeukendrup A, Gleeson M. (2025). Sport nutrition (4th ed.). Human Kinetics.