Alanine is a non-essential α-amino acid involved in protein biosynthesis that is produced by the human body from other amino acids. It is the main amino acid released by the human forearm muscle and its production in skeletal muscle may be related to the rapid oxidation of branched-chain amino acids. It helps the human body convert glucose into energy and has the function of removing excess toxins from the liver. 

It is produced synthetically by acetaldehyde, sodium cyanide, ammonium chloride (Strecker reaction). Commercially, it is used in the forms L-alanine and β-alanine.

It is an α-amino acid.

Amino acids play a key metabolic function in the human body and are constituents of proteins. 

As food additives they perform different functions: preservatives, flavour enhancers, food supplements and more.

Amino acids together with their salts are used in cosmetics as conditioning agents for both hair and skin (e.g. as moisturisers and other similar functions). Moisturisers are different in nature: the best are the natural ones that exploit the mechanism of integration between the ingredient and the skin by moisturising the horny hydrolipid film, i.e. the thin protective layer that covers the epidermis protecting it from harmful external microbes, keeping the skin moisturised and supple and its pH or acidity value between 4 and 6.  Then there are the occlusive moisturisers, usually derived from petroleum (Paraffinum, Paraffinum liquidum and others), but also triglycerides, lanolin oil, natural or synthetic waxes, fatty acid esters and others that create an artificial occlusive layer on the stratum corneum of the skin with the advantage of accelerating the protective process but with the disadvantage of preventing the skin's natural transpiration.

α-amino acids that have similar physical structures undergo similar changes with regard to solubility in water/ethanol mixtures, and technologies to separate α-amino acids from industrial residues, which may not even be innocuous, are constantly being improved. However, many data on the solubility in water-ethanol and ethanol of some α-amino acids are contradictory or even lacking, and the effects of ethanol on the solubility of amino acids may be different. Overall, the scientific literature considers that α-amino acids do not pose significant problems for human health when taken orally, except in people with certain genetic diseases.

Food safety: amino acid α generally considered safe.

Cosmetic safety: amino acid α generally considered safe when formulated to be non-irritant.

Alanine occurs as a white crystalline powder, odourless with a sweetish taste, soluble in water, ethanol, insoluble in ether and acetone.

What it is used for and where

Medical

Some clinical studies have reported alanine as a modulator of anxiety behaviour (1), while the better-known β-alanine is known as one of the most popular sports supplements as an ergogenic strategy to increase intramuscular carnosine content. and for which the associated potential adverse effects as well as benefits have been examined (2). Any positive results depend on the role and high levels of carnosine as an antioxidant. However, the scientific literature has not revealed any changes in metabolic contribution (3).

L-alanine is used in parenteral and enteral nutrition and plays an important role in the transfer of nitrogen from tissue sites to the liver. Intermediate component for the production of medicines.

Cosmetics

Alanine plays an adjuvant role in cell protection as a moisturiser.

Food

Dietary L-alanine is synthesised by the reaction of aspartate 4-decarboxylase, an enzyme, with the amino acid L-aspartate.  Flavour enhancer, sweetener, preservative.

Agriculture

Food supplement and acid correcting agent in agriculture and animal feed, and intermediate component in the production of various organic chemicals. It has also shown a cholesterol-lowering effect in animals.

The most relevant studies on this ingredient have been selected with a summary of their contents:

Alanine studies

Typical commercial product characteristics L-Alanine

• Molecular Formula     C₃H₇NO₂
• Molecular Weight     89.09
• Exact Mass    89.093
• CAS  56-41-7
• UNII    OF5P57N2ZX
• EC Number   200-273-8
• DSSTox Substance ID  
• IUPAC  (2S)-2-aminopropanoic acid
• InChI=1S/C3H7NO2/c1-2(4)3(5)6/h2H,4H2,1H3,(H,5,6)/t2-/m0/s1
• InChl Key      QNAYBMKLOCPYGJ-REOHCLBHSA-N
• SMILES   CC(C(=O)O)N
• MDL number   MFCD00064410
• PubChem Substance ID    24891260
• ChEBI  16977
• Beilstein  1720248
• eCl@ss      32160406
• RTECS   AY2990000
• NACRES  NA.26

Synonyms

• L-alanine
• (2S)-2-aminopropanoic acid
• L-α-Aminopropionic acid

References_________________________________________________________________

(1) Francisco Eda S, Guedes RC. Neonatal taurine and alanine modulate anxiety-like behavior and decelerate cortical spreading depression in rats previously suckled under different litter sizes. Amino Acids. 2015 Nov;47(11):2437-45. doi: 10.1007/s00726-015-2036-8. 

(2) Hoffman JR, Emerson NS, Stout JR. β-Alanine supplementation. Curr Sports Med Rep. 2012 Jul-Aug;11(4):189-95. doi: 10.1249/JSR.0b013e3182604983.

(3) Norberto MS, Barbieri RA, Bertucci DR, Gobbi RB, Campos EZ, Zagatto AM, De Freitas EC, Papoti M. Beta alanine supplementation effects on metabolic contribution and swimming performance. J Int Soc Sports Nutr. 2020 Jul 25;17(1):40. doi: 10.1186/s12970-020-00365-6. Erratum in: J Int Soc Sports Nutr. 2020 Oct 8;17(1):50.