Linolenic acid

The alpha linolenic acid (linolene-lini - linseed), ALA for short, is a triple unsaturated, essential C18: 3 omega-3 acid (also called omega-3 fatty acid) which occurs in numerous vegetable oils. The term "alpha-linolenic acid" is often used synonymously to linolenic acid.
The gamma-linolenic acid, also called gamolenic acid, has a slightly different chemical structure than C18: 3-omega-6 acid (omega-6 fatty acid).
Linolenic acids are found in vegetable oils, such as Borago officinalis seed oil (borage), Cannabis sativa (hemp), linseed oil, walnut oil, rapeseed oil and soybean oil.
Linoleic acid, an omega-6 fatty acid similar to linolenic acid by name, has one double bond less than linolenic acid (see figure).
Linolenic acid, chemically bound, is found as an ester in many triglycerides which make up a large part of natural fats and oils.
The triglycerides of a whole range of naturally extracted vegetable oils are rich in linolenic acid residues.

Gamma-linolenic acid is used medicinally to fatten the external skin in atopic eczema. It is also used in the case of age- or drug-related (e.g. through the use of retinoids) desiccation of the skin.
The use of gamma-linolenic acid in acne vulgaris requires further investigations.

1. Desbois AP et al (2013) Antibacterial activity of long-chain polyunsaturated fatty acids against Propionibacterium acnes and Staphylococcus aureus. Mar Drugs 11:4544-4557.
2. Fujii M et al (2013) Deficiency of n-6 polyunsaturated fatty acids is mainly responsible for atopic dermatitis-like pruritic skin inflammation in special diet-fed hairless mice. Exp Dermatol 22:272-277.
3. Kawamura A et al (2011) Dietary supplementation of gamma-linolenic acid improves skin parameters in subjects with dry skin and mild atopic dermatitis. J Oleo Sci 60:597-607.
   
4. Lee HR et al (2014) The efficacy and safety of gamma-linolenic acid for the treatment of acne vulgaris. Int J Dermatol 53:e199-e200.