Evening primrose oil is a natural oil extracted from the seeds of the Oenothera biennis plant. Native to eastern and central North America, this plant is recognized by its yellow flowers that open at dusk. Historically, various parts of the plant have been utilized in traditional practices.
The Primary Active Ingredient: Gamma-Linolenic Acid (GLA)
Gamma-Linolenic Acid (GLA) is a key component of evening primrose oil. It is an omega-6 polyunsaturated fatty acid (PUFA). GLA is considered a conditionally essential fatty acid, meaning the body can produce some, but dietary intake can be important under certain conditions.
Evening primrose oil is rich in GLA, typically containing 7% to 14% of its total fatty acids. This concentration makes evening primrose oil one of the recognized botanical sources of GLA, alongside borage oil and black currant seed oil.
Other Important Fatty Acids
Evening primrose oil also contains other fatty acids. Linoleic acid (LA) is present in the highest concentration, typically ranging from 70% to 74% of the oil’s fatty acids. As an omega-6 fatty acid, LA is essential, meaning the human body cannot produce it and must obtain it from dietary sources. It serves as a precursor to GLA in the body’s metabolic pathways.
The oil includes monounsaturated fatty acids like oleic acid, an omega-9 fatty acid, usually found in percentages ranging from 5% to 12%. Saturated fatty acids, such as palmitic acid (6% to 7%) and stearic acid (1% to 2%), are present as minor components.
How These Components Interact in the Body
Once consumed, the fatty acids in primrose oil undergo metabolic transformations in the body. Linoleic acid (LA) is converted into gamma-linolenic acid (GLA) through the action of an enzyme called delta-6-desaturase. This conversion is a key step in the pathway of omega-6 fatty acid metabolism. Subsequently, GLA is elongated to form dihomo-gamma-linolenic acid (DGLA).
DGLA then serves as a precursor for the synthesis of various biologically active compounds known as eicosanoids. These include specific types of prostaglandins, such as series-1 prostaglandins (e.g., PGE1). Eicosanoids are signaling molecules that influence a range of cellular functions, acting locally at the site of their synthesis. The presence of DGLA and its subsequent conversion products contribute to fundamental physiological processes at a cellular level.