For linoleic acid (no n), see linoleic acid. Gamma-linolenic acid or GLA (γ-Linolenic acid), (INN and USAN gamolenic acid) is a fatty acid found primarily in vegetable oils. It is sold as a dietary supplement for a variety of human health problems, although there is little or no evidence of its effectiveness.LA is obtained from vegetable oils such as evening primrose (Oenothera biennis) oil (EPO), blackcurrant seed oil, borage seed oil, and hemp seed oil. GLA is also found in varying amounts in edible hemp seeds, oats, barley, and spirulina.