γ-Linolenic Acid (GLA) naturally exists in plants and microorganisms. It is currently known that there are more than 80 species of higher plant seeds in the world that contain GLA, such as Willowaceae, Saxifragaceae, Scrophulariaceae , Ranunculus, Acer and Boraginaceae.

Chemical Structure and Physicochemical Properties of γ-Linolenic Acid

γ-linolenic acid is a new fatty acid found in the seed oil of evening primrose. γ-linolenic acid belongs to all-cis polyunsaturated fatty acids and is an isomer of α-linolenic acid. The chemical name is 6,9,12-octadecatrienoic acid, the molecular formula is C18H30O2, the molecular weight is 278, and the CAS number is 506-26-3.

GLA is a colorless oily liquid, insoluble in water but easily soluble in non-polar solvents such as ether. It is unstable in the air, and it is easily oxidized especially under high temperature conditions. Under alkaline conditions, the isomerization reaction of the configuration of the double bond is prone to occur to form conjugated polyene acids.

Physiological Functions and Effects of γ-Linolenic Acid

Sterilization, Anti-inflammatory: GLA has inhibitory effects on a variety of Gram-negative and Gram-positive bacteria. GLA inhibits the growth of bacteria by increasing the level of peroxidation and changing the permeability of the membrane, and can be used in the treatment of various inflammatory diseases involving oxidative stress, such as rheumatoid arthritis, inflammatory bowel disease, nephritis, bronchial asthma and coronary arterial disease etc.

Lowering blood fat: After GLA is converted into AA in the body, it can enhance insulin sensitivity, reduce lipogenesis, and increase fat oxidation. GLA can reduce the rebound after weight loss in the crowd, and the maintenance time is longer.

GLA can inhibit platelet aggregation and thromboxane (TXA) synthesis in vivo. GLA can directly produce prostaglandins to inhibit platelet aggregation, and then derivate into DGLA to reduce the production of AA, inhibit the activity of platelet TXA synthase, and adjust the ratio of TXA and prostaglandins to improve vascular conditions.

Others:  GLA can enhance human immune function, inhibit gastric ulcer and gastric bleeding, relieve menopausal syndrome, and reduce the severity of dermatitis.It can be used to treat schizophrenia, common ichthyosis, women's menstrual syndrome, periodic breast pain, Huntington's disease, phenylketonuria, Parkinson's disease, asthma, eczema, hyperparathyroidism and other diseases.

Common Consumption Methods and Recommended Intake

As a food : As a food additive or as a nutritional supplement, long-term use can correct lipid metabolism disorders and enhance the body's immunity. γ-linolenic acid can be used to prepare milk powder, vegetable oil, and beverages, and the dosage is 20~50g/kg.

As a health food: Evening primrose oil rich in gamma-linolenic acid is used as a health product in the United States, Canada, Germany, the United Kingdom, and Japan.

As a medicine, it is clinically used as a blood lipid-lowering drug in the form of evening primrose capsules to treat hypertension, cerebral thrombosis, atherosclerosis, coronary heart disease, atopic eczema and breast diseases.

As a cosmetic, a small amount can be absorbed through the skin to produce effects. From the blood circulation to the phospholipids of the cell wall, it can delay skin aging. It reacts with kojic acid to form kojic acid monolinolenate, which can be used as an inhibitor of tyrosinase and has anti-pigmentation properties. Generatively active, it can be used as an active ingredient in brightening cosmetics and in the form of ointments for anti-pigmentation.

Recommended Intake

FAO/WHO recommends that the total polyunsaturated fatty acid should be 6%~11%E, and the n-6 polyunsaturated fatty acid represented by LA should be 2.5%~9%E. EAR is 2%E. According to the dietary allowance (RDA) recommended by the Chinese Nutrition Society: 100mg/kg per day for infants; 36mg/kg per day for adults.