L'enotera - Oenothera biennis, fam. Onagraceae - is a biennial herbaceous plant up to 150 centimeters high.
Native to North America, but nowadays cosmopolitan, Enera prefers dry and sandy places. The leaves, opposite and lanceolate, are about 10 - 20 cm long and have an irregularly toothed margin; the flowers, yellow in color, collect in an apical inflorescence that blooms in the evening.
Thanks to its particular richness in polyunsaturated fatty acids, and in particular GLA, evening primrose oil is proposed as a food supplement for the treatment of various conditions, among which we mention: premenstrual syndrome, atopic dermatitis, rheumatoid arthritis, breast pain associated with the menstrual cycle, symptoms of menopause, diabetes and coronary heart disease. Gamma-linolenic acid can in fact suppress inflammation by inhibiting the synthesis of pro-inflammatory prostaglandins (PGE2) and leukotrienes, as well as producing series 1 prostaglandins (PGE1) with antiplatelet, cardioprotective, anti-atherogenic, vasodilatory and anti-inflammatory activity. The most studied application of evening primrose oil concerns the treatment of atopic dermatitis; there are conflicting results in this regard. It is possible that the anti-inflammatory activity of evening primrose oil is enhanced by a low glycemic load diet rich in fish; on the contrary, the excess sugar and the reduced intake of EPA and DHA could reduce the anti-inflammatory action of this food supplement. For a series of biochemical reasons due to the transformation of gamma linolenic acid, first into DGLA (which has anti-inflammatory effects) and then into arachidonic acid (which has pro-inflammatory effects), the simultaneous association of EPA and GLA has been proposed to slow down the conversion of DGLA (obtained from the latter) to arachidonic acid. The association with vitamin E is also recommended to control the production of free radicals.
Evening primrose oil is a powerful inhibitor of 5-alpha reductase, both type I and type II, and could therefore exert a certain beneficial effect in the prevention of acne, prostatic hypertrophy and hair loss.
Evening primrose oil is generally standardized in gamma-linolenic acid and marketed in capsules. The recommended doses are 6-8 grams in the adult and 2-4 grams in the child; the administration is oral. In general, the dosages are calibrated to provide 160-400 grams of gamma linolenic acid per day.
Evening primrose oil is well tolerated by most people; mild side effects include headaches and gastrointestinal problems (dyspepsia, nausea, loose stools). To be used with caution and under strict medical supervision in the presence of schizophrenia. Given the seriousness of some conditions for which evening primrose oil is indicated, it is recommended in any case a preventive medical consultation.
