Flax

Zahra Najdgholami et al. (2025) · Frontiers in endocrinology

This 12-week open-label randomized controlled trial with 70 women explored whether daily flaxseed intake could shift reproductive hormone patterns in polycystic ovary syndrome (PCOS), a common endocrine condition affecting 6 to 15 percent of women of reproductive age. PCOS involves hyperandrogenism (elevated androgen hormones) and disrupted ovulation, often accompanied by a low or borderline follicle-stimulating hormone (FSH) that limits egg follicles from fully maturing. Flaxseed is a plant-based food rich in phytoestrogenic lignans (plant compounds structurally similar to estrogen) and omega-3 fatty acids, both proposed to influence the hormone pathways governing follicle development and gonadotropin balance. Seventy women diagnosed with PCOS at a clinic in Ahvaz, Iran were randomly assigned to 12 weeks of either 30 grams of daily milled flaxseed added to salads, yogurt, or cold drinks, combined with standard diet and exercise guidance, or the same lifestyle guidance without flaxseed. Blood tests measuring FSH, luteinizing hormone (LH), anti-Mullerian hormone, estradiol, DHEAS, and androstenedione were drawn at baseline and after 12 weeks using enzyme immunoassays and chemiluminescent assays, timed to each participant's menstrual cycle phase where applicable. FSH rose significantly more in the flaxseed group than in controls (treatment effect 0.87, 95% CI 0.086-1.75, p=0.027), meaning flaxseed users saw a measurably larger increase in this follicle-stimulating hormone than those on lifestyle changes alone. The ratio of LH to FSH also dropped significantly with flaxseed (treatment effect -0.341, 95% CI -0.63 to -0.08, p=0.031), a lower ratio pointing toward more balanced gonadotropin secretion, since an elevated LH/FSH ratio is a hallmark of PCOS. No significant between-group changes appeared for AMH, LH alone, estradiol, DHEAS, or androstenedione, indicating flaxseed's measured effect was specific to FSH and its ratio to LH rather than the broader hormone panel. Weight, BMI, lipids, and blood sugar stayed similar between groups, and no adverse events were reported, suggesting the 30-gram daily dose was well tolerated over the 12 weeks. The authors propose that flaxseed's omega-3 fatty acids and lignans may support follicle-stimulating hormone receptor activity and gonadotropin regulation, though this mechanism was not directly tested in the trial. The open-label design, unavoidable for a dietary intervention, the single-center setting, and the absence of testosterone and insulin measurements limit how broadly the results extend. The authors identify larger, longer randomized trials incorporating androgen and insulin outcomes as the needed next step for confirming flaxseed's role in PCOS management.

Aliasghar Manouchehri et al. (2023) · JBRA assisted reproduction

Polycystic ovary syndrome (PCOS) is one of the most common hormone-related conditions affecting women of reproductive age, estimated to affect 4-25% of women depending on how it is diagnosed (14.6% in Iran). Beyond irregular periods and fertility struggles, PCOS often comes with insulin resistance, weight gain, acne, excess hair growth, and long-term metabolic risk. Because standard medications can carry side effects, researchers have looked to medicinal plants as gentler options. This review pulls together what is known about nine herbs -- from aloe vera to flax -- and how each is thought to act on the hormonal and metabolic disruptions behind PCOS. Unlike a systematic review with a registered search protocol, this is a narrative synthesis: the authors describe the proposed mechanism of each of nine plants -- aloe vera, chamomile, chaste tree, cinnamon, ginseng, stachys, fennel, liquorice, and flax -- based mainly on animal and laboratory studies rather than human clinical trials. Each plant's key active compound and hypothesized mechanism of action are summarized in a comparison table, covering effects on hormone levels, ovarian tissue, insulin sensitivity, and inflammation. Each herb is proposed to work differently. Cinnamon appears to improve insulin sensitivity and lower blood sugar and lipids by affecting insulin-receptor signaling. Chaste tree and fennel are proposed to shift the balance of reproductive hormones (chaste tree lowering testosterone, fennel raising progesterone and thickening the uterine lining). Flax's lignans are linked to lower androgen levels and less excess hair growth (hirsutism), while stachys is proposed to ease abnormal uterine bleeding by damping estrogen receptor activity. Chamomile and aloe vera are described as supportive of ovarian tissue and follicle development, and ginseng and liquorice are framed around broader immune and metabolic support. Importantly, the review does not report clinical trial results, statistics, or human outcome data for any of these plants -- the mechanisms described come mainly from animal models and lab studies, not from testing in women with PCOS. The authors see herbal medicine as a promising, low-side-effect complement to PCOS care, working mainly through immune support and cycle regulation rather than direct hormone replacement -- but they are careful to say more research time is needed. Because this is a synthesis of mostly preclinical and mechanistic findings, none of these nine plants can be considered proven PCOS treatments; each is better read as a lead for future controlled human trials than as an established remedy to try in place of medical care.