Beta-alanine is an amino acid the body does not use to build proteins; muscle uses it to make carnosine, which helps buffer the acid that builds up during hard, short efforts. As a supplement it is taken by athletes hoping to improve high-intensity exercise lasting from about 30 seconds to a few minutes.
Also known as: β-alanine, CarnoSyn, carnosine precursor.
Most studies in the review the NIH Office of Dietary Supplements (ODS) describes used 1.6 to 6.4 g a day, split into two to four servings, for 4 to 8 weeks. The International Society of Sports Nutrition (ISSN) describes 4 to 6 g a day for at least 2 to 4 weeks, in divided servings of about 1.6 g or less. These are study protocols, not a recommendation.
It is sold in the US as a dietary supplement. Under the 1994 dietary supplement law (DSHEA), FDA does not approve dietary supplements before they are marketed, and the maker, not FDA, is responsible for safety and labeling. ODS says diets supply from none (vegans) to about 1 g a day (heavy meat eaters), and that 4 to 6 g a day for 10 weeks can raise muscle carnosine by up to 80%, though the response varies widely between people.
What studies show is mixed. A 2017 meta-analysis of 40 placebo-controlled studies (1,461 people) found a small overall benefit, larger in exercise lasting 30 seconds to 10 minutes; ODS notes these were mostly small, short studies with varied methods. A Department of Defense-sponsored review of 20 trials concluded the evidence did not support beta-alanine for active adults, while the ISSN position stand concluded it can improve high-intensity exercise lasting about 1 to 4 minutes. Several ISSN authors list supplement-industry affiliations. ODS says there is not enough expert agreement on its value or on its safety with regular use for several months or longer.
Safety, per ODS: 1.6 to 6.4 g a day for up to 8 weeks appears safe. Single servings of at least 800 mg, or more than 10 mg per kg of body weight, can cause paresthesia, a tingling, prickling or burning feeling in the face, neck, hands and upper body that usually lasts 60 to 90 minutes and is not harmful. Smaller divided servings or sustained-release forms reduce it. Itchy skin has also been reported. There are no safety data beyond 1 year.
We could not find a single published half-life or time to peak for beta-alanine that applies to a supplement dose, so we do not list one. What matters in studies is the slow rise in muscle carnosine over weeks; ODS describes a study in which levels took 6 to 15 weeks to return to baseline after people stopped, depending on how strongly they had responded.
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