The effectivity of evening primrose oil

The effectivity of evening primrose oil.

Evening primrose (Oenothera L.) is a plant belonging to the Onagraceae family. There are about 145 species in the genus Oenothera L. The most numerous species in the Oenothera L. family is Oenothera biennis, which also has the best studied biological activity. It has been indicated that Oenothera biennis is beneficial in the treatment of many diseases^[1].

Evening primrose oil is obtained from Oenothera biennis seeds using the cold-pressing method^[1] or solvent extraction^[2]. Evening primrose oil is very high in linoleic (70–74%) and gamma-linolenic (8–10%) acids, and also contains other fatty acids: palmitic acid, oleic acid, stearic acid, and (in smaller amounts) myristic acid, oleopalmitic acid, vaccenic acid, eicosanoic acid, and eicosenoic acid^[1]. 

Biological Activity of Evening Primrose Oil.

The most important components in terms of quantity are polyunsaturated fatty acids, mainly linoleic acid and gamma-linolenic acid which belong to the group of omega-6 acids^[1].

Linoleic acid is classified as an essential fatty acid. They are not synthesized by the human body and must be obtained from diet. Because they are precursors of molecules that lead to the synthesis of anti-inflammatory substances, they help numerous tissues in the human body operate properly^[1].

Linoleic acid plays an important role in the proper functioning of the skin, especially the stratum corneum, in which it is one of the main components of the ceramides building the lipid layer. It has been shown that the presence of this acid prevents the skin from peeling and the loss of water through the epidermis, while at the same time improving skin softness and elasticity and regulating the process of epidermal keratinization. A deficiency of linoleic acid, which is contained in large quantities in ceramide, leads to its replacement by oleic acid. This causes a deterioration in the protective properties of the epidermis^[1].

Evening primrose oil also has a beneficial moisturizing effect on the mucous membrane in acne patients treated with isotretinoin because of its linoleic acid content. This means that supplementing the skin with evening primrose oil helps the skin’s water equilibrium, which has been weakened by isotretinoin treatment. Moreover, gamma-linolenic acid, contained in large amounts in the oil, is a source of the anti-inflammatory, which have anti-proliferative properties that effectively prevent epidermal hyperproliferation. Furthermore, these compounds inhibit the proliferation of smooth muscle cells and prevent the development of atherosclerotic plaque^[1].

Uses & Effectiveness.

• Premenstrual syndrome (PMS)

PMS is a condition, which is associated with somatic, emotional and behavioral symptoms during the women menstruation. Anxiety, depression, acne, fatigue, and headache are common symptoms of PMS. Insomnia and suicidal thoughts are severe symptoms of premenstrual dysphoric disorders. Menstruating women of 85% are affected by these symptoms. PMS is characterized by over 150 clinical symptoms (behavioral, psychological, and physical) including cyclical mastalgia, headache, backache, irritability, depression, food carving, and irritable bowel syndrome during the luteal phase of menstrual cycles. Low level of prostaglandin E1, as the result of a deficiency in essential fatty acids causes high sensitivity to prolactin, which produces at ovulation time and increases the high level during the luteal phases^[3].

Many clinical trials have been conducted to test the therapeutic efficacy of evening primrose oil in the treatment of PMS. Linoleic acid promotes prostaglandin synthesis and alleviates PMS^[3]. Even though a review of placebo-controlled trials of evening primrose oil found no benefit in PMS^[4], the results of many clinical research demonstrated that evening primrose oil is effective and safe in the management of PMS during menstruation^[3].

• Menopause

Menopause is an evolutionary female stage that is experienced by all women at an older age and exposes women to a wide range of variations. According to the World Health Organization (WHO), menopause occurs 12 months after amenorrhea and between the ages of 45 and 55 years^[5].

Lower estrogen levels during menopause are associated with some side effects that can affect a woman’s quality of life and weaken her health and well-being. Night sweats, osteoporosis, vaginal dryness, dyspareunia, moral swings, joint pain, palpitations, restlessness, and urine symptoms are some of the symptoms that women encounter at this time^[5].

Hot flashes and night sweats are the most common and annoying consequences that can affect enjoying work and social activities, leisure time, mood, communication with others, sexual activity, enjoyment of life, and the quality of life^[5].

The evening primrose oil is a phytoestrogenic properties. Its mechanism in improving hot flashes and night sweats is unclear although it may act as an estrogen agonist, and antagonist and through interaction with the estrogen receptor. When estrogen levels are low, phytoestrogens function as agonists or antagonists of the estrogen receptor, providing higher estrogenic effects and compensating for the loss of androgen 17 beta-estradiol in menopause. For this reason, many women use phytoestrogenic family herbs as a supplement and hormone replacement therapy in menopause to improve the symptoms of this period^[5].

Based on the findings of the present study, evening primrose oil did not affect the severity, duration, and frequency of hot flashes, but it was effective on the frequency and severity of night sweats^[5].

In addition, there is a study reported that menopause transition is one stage in women’s lives that can affect the psychological condition and increase depression prevalence in them. The prevalence of psychological disorders in menopause women to be more than 30%. Depressed mood, irritation, anxiety, and mental exhaustion were explored as four symptoms in psychiatric disorders. Since a great part of symptoms can be due to the complications of lack of estrogen production, making up for this deficiency can certainly prevent from the creation and worsening of these complications^[6].

The results revealed that consuming the plant oil for one-month enhanced mood and reduced psychological illnesses. High levels of unsaturated fatty acids, particularly gamma linoleic acid in evening primrose oil, could be one cause for the reduction in psychiatric symptoms^[6].

• Atopic dermatitis

Atopic dermatitis is a chronic, recurrent, and inflammatory skin disease characterized by dry skin, itch, and erythema. It is multifactorial and has complicated immunological abnormal responses, including damage to the epidermal barrier, genetic factors, and environmental causes. Some researchers have suggested that atopic dermatitis may be related to the abnormal metabolism of essential fatty acid, especially the abnormality in the production of gamma-linolenic acid. In some atopic dermatitis patient groups, the functional deficiency of delta-6 desaturase was discussed as a factor of disease. Linoleic acid is converted to gamma-linolenic acid by delta-6 desaturase, which is ultimately metabolized into dihomo-gamma-linolenic acid (DGLA). In patients with atopic dermatitis, a functional impairment of delta-6 desaturase causes an increase in linoleic acid and a decrease in gamma-linolenic acid, DGLA, arachidonic acid, and prostaglandin E1 (PGE1). PGE1 deficiency can cause immunological dysregulation and the dominance of inflammatory PGE2 and PGF2, resulting in atopic dermatitis^[7].

Evening primrose oil has been shown to be effective in treating atopic dermatitis in pediatric in numerous studies. They also found that as compared to controls, pediatric patients treated with gamma-linolenic acid had lower levels of inflammation, dryness, scaling, and overall severity. Some additional studies have also confirmed the beneficial role of evening primrose oil in adult which reported that adult patients receiving gamma-linolenic acid show gradual improvement in pruritus, erythema, vesiculation and oozing^[8].

Interactions, Adverse Effects, and Contraindications

Evening primrose oil is generally well tolerated, with reported minor adverse effects including gastrointestinal disturbance (e.g., abdominal pain, indigestion, nausea, softening of stools) and headaches. In the 1980s, two case reports involving just five patients raised concerns that evening primrose oil could worsen epilepsy or lower the seizure threshold in patients using phenothiazines for schizophrenia. Although caution was advised for patients taking phenothiazine neuroleptics or anticonvulsants, neuroleptics themselves can induce seizures^[2].

The effects of essential fatty acids supplementation during pregnancy and lactation remain largely unknown, and their use cannot be recommended. Additional concerns have been expressed about the negative effects of evening primrose oil supplementation on disorders such as platelet aggregation, cholesterol, and blood pressure, despite the lack of data to support these claims^[2].

References.

1. Timoszuk M, Bielawska K, Skrzydlewska E. Evening Primrose (Oenothera biennis) Biological Activity Dependent on Chemical Composition. Antioxidants (Basel). [Internet]. 2018 [cited 2022 Jan 13]; 7: 1-11. Available form:http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6116039/ 
2. Bayles B, Usatine R. Evening Primrose Oil. American Family Physician. [Internet]. 2009 [cited 2022 Jan 13]; 80: 1405-8. Available form:http://www.aafp.org/afp/2009/1215/p1405.html 
3. Mahboubi M. Evening Primrose (Oenothera biennis) Oil in Management of Female Ailments. Journal of Menopausal Medicine. [Internet]. 2019 [cited 2022 Jan 13]; 25: 74-82. Available form:http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6718646/ 
4. Dickerson L, Mazyck P, Hunter M. Premenstrual Syndrome. American Family Physician. [Internet]. 2003 [cited 2022 Jan 13]; 67: 1743-52. Available form:http://www.aafp.org/afp/2003/0415/p1743.html
5. Kazemi F, Masoumi SZ, Shayan A, Oshvandi K. The Effect of Evening Primrose Oil Capsule on Hot Flashes and Night Sweats in Postmenopausal Women: A Single-Blind Randomized Controlled Trial. Journal of Menopausal Medicine. [Internet]. 2021 [cited 2022 Jan 13]; 27: 8-14. Available form:
   http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8102809/          
6. Safdari F, Motaghi Dastenaei B, Kheiri S, Karimiankakolaki Z. Effect of Evening Primrose Oil on Postmenopausal Psychological Symptoms: A Triple-Blind Randomized Clinical Trial. Journal of Menopausal Medicine. [Internet]. 2021 [cited 2022 Jan 13]; 27: 58-65. Available form:
   http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8408320/     
7. Chung B, Park S, Jung M, Kim H, Park C. Effect of evening primrose oil on Korean patients with mild atopic dermatitis: A randomized, double-blinded, placebo-controlled clinical study. Ann Dermatol. [Internet]. 2018 [cited 2022 Jan 13]; 30: 409-16. Available form: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6029968/    
8. Chung B, Kim J, Cho S, Ahn I, Kim H, Park C, et al. Dose-Dependent Effects of Evening Primrose Oil in Children and Adolescents with Atopic Dermatitis. Ann Dermatol. [Internet]. 2013 [cited 2022 Jan 13]; 25: 285-91. Available form: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3756191/