Safety and influence of a novel extract of fenugreek on healthy young women: a randomized, double-blinded, placebo-controlled study

The reproductive cycle is regulated by the hormones of the hypothalamic-pituitary-gonadal (HPG) axis; mainly the estradiol, progesterone, testosterone, follicle stimulating hormone (FSH), and luteinizing hormone (LH) [1]. Puberty starts with the rise in LH and estradiol secretions followed by the first menstruation [2]. In the reproductive years, cyclic rise of estrogen and progesterone occurs. While increase in estrogen and progesterone promoted endometrial proliferation and ovulation, the decreased level leads to endometrial mucosal degeneration (i.e., menstruation) [3]. Estradiol and progesterone levels start declining with the perimenopausal stage and return to pre-adolescent levels by the menopause, which usually occur between the age of 45 and 55 [3]. LH and FSH increase in the absence of ovarian estrogenic feedback [2]. Typical variations in the hormone levels during the life cycle of a woman can be depicted as Fig. 1 [4].

The constant variations in the hormonal levels normally cause a number of physiological and psychological changes in a woman’s life. During the menstrual phase, woman may experience mood swings and Dysmenorrhea, a severe lower abdominal pain of cramping nature accompanied by vomiting, headache, back pain, diarrhoea and fatigue [5]. Prostaglandins produced by the linings of the uterus have been identified as one of the reasons for the pain since it is known to cause abnormal contractile activity leading to ischemia and hypoxia of the uterus and hence increased sensitivity of the nerve endings [6]. Non-steroid anti-inflammatory drugs (NSAIDs) are recognized as the first-line treatment in dysmenorrhea [7], though 25 to 30% failure normally reported [8]. At the menopausal phase, women experience physiologic deterioration of hypothalamic-pituitary-ovarian axis function resulting in hormonal imbalance and a variety of symptoms such as hot flushes, sweating, sleep disturbance, mood swings, depression, cognitive decline, vaginal dryness and sexual dysfunction occur with a significant impact on their quality of life [9, 10].

Several herbal remedies have been reported for alleviating various issues associated with various stages of life of a woman, primarily due to the hormonal variations [11]. Fenugreek (Trigonella foenum-graecum) is a popular kitchen spice and medicinal herb that has been shown to possess many useful properties against various physiological issues of women. Fenugreek seeds have been reported to alleviate dysmenorrhea associated with menstruation [12]; supports breast size due to the mastogenic effect [13]; promotes healthy sexual life and mood with a significant impact on libido and vitality among young women [14]; helps to reduce inflammation and body pain associated with child birth [12]; helps the contraction of uterus after delivery and is a galactogogue [15]. In the case of menopausal women, it has been shown to ameliorate various menopausal discomforts related to vasomotor, urogenetic, psychological issues [16, 17]. Despite all the benefits, human safety studies especially looking at the hormonal safety of fenugreek and its extracts are limited.

Recently, a hydro-ethanolic extract of fenugreek seeds (FHE; Patented and registered as FenuSMART^®) containing protodioscin and trigonelline in a 3:1 ratio with around 10% of protodioscin was reported to alleviate both post and peri-menopausal discomforts when supplemented at 250 mg × 2/day for 42 days [16, 17]. These studies also have revealed a significant hormonal change (estradiol, progesterone, and testosterone) towards attaining a normal balanced hormone levels among menopausal women [16, 17]. FHE was shown to be tolerated upon supplementation at 500 mg × 2/day for 90 days on 88 postmenopausal women, without significant side effects or adverse events [18]. Therefore, we hypothesised that FHE would also be safe on healthy menstruating women since none of the early studies have shown uncontrolled variations in the reproductive hormones when supplemented to post and peri-menopausal women. Thus, the objective of the present study was to investigate the safety and influence of FHE on the hormone levels of young women at 250 mg × 2/day for 42 days.

Hormonal changes occur as women ages through menstrual cycles and menopausal phases as depicted in Fig. 1. The decline in androgen levels normally starts long before menopause; specifically from the perimenopausal age of around 47.5 years [22‐24]. By the mid-30s or 40s, the normal activities of ovaries reduce and the process of ovulation becomes irregular [25]. In the perimenopause period, the levels of estradiol and progesterone decreases and in menopause, ovary can no longer release ova, and LH as well as FSH increase in the absence of ovarian estrogen feedback [2]. Estradiol and progesterone modulate sexual desire in women and the gradual and age-related cessation of ovarian function associated with natural menopause decreases the levels of these steroidal hormones and hence contribute towards the diminished sexual desire. This is a general observation among a significant portion of postmenopausal women [26].

The present study following a purposive sampling plan to select healthy women having some degree of sexual issues and irritability problems as reflected in the MRS scores, demonstrated a significant increase in estradiol and testosterone levels with a significant reduction in sexual issues and irritability scores when supplemented with FHE for 42 days at 250 mg × 2/day. About 81% of participants in placebo and 88% in FHE group reported scores between one and four for sexual problems and irritability, indicating mild to medium issues with regard to sexual functioning. However, the participants did not report to have any notable vasomotor symptoms at the time of enrolment. Upon hormonal analysis, it was found that these women had relatively low levels of estrogen and testosterone though within the reference range.

Estradiol and testosterone are the major hormones that have been implicated for modulating women’s sexual desire and functions [26]. These hormones activate the Hypothalamic-Pituitary-Gonadal (HPG) axis by binding with estrogen receptors and the activation of HPG axis is necessary for fertility [27, 28]. Decrease in serum estrogen causes a decrease in clitoral intracavernosal, vaginal, and urethral blood flow, due to diffuse clitoral brosis, thinned vaginal epithelial layers, and decreased vaginal submucosal vasculature [29, 30]. In our study, the level of estradiol was significantly increased in FHE group and no significant change was observed in placebo group at the end of the study (Table 3). This has further correlated with the results of MRS scores, especially in the percentage improvement in sexual problems and irritability scores (Fig. 3). There was no significant change in the hormone levels or MRS scores in placebo.

The observation that the supplementation of FHE increased the estrogen and testosterone levels and significantly improved the quality of sexual functions and quality of life among participants who had issues at the baseline levels indicates the beneficial effect of FHE [31]. Earlier studies have also reported significant enhancement in both estradiol and testosterones among menopausal and healthy population having low libido when supplemented with fenugreek extracts [14, 16‐18]. Elevated concentrations of endogenous estrogen and hormonal therapy with estrogen have already been reported to ease the menopausal discomforts [32]. However, the enhancement in estradiol and testosterone among participants with normal baseline levels were not significant (P > 0.05), indicating relatively weak estrogenic activity for FHE. Phytoestrogens are generally shown to possess weak binding with receptors [33]. So, under normal healthy conditions when there is enough natural estrogen in the body, the receptors available for binding with phytoestrogens will be limited. But, in the case of insufficient estrogen levels, phytoestrogens may bind to the receptors and support to ameliorate the symptoms associated with low estrogen levels. Phytoestrogens can also affect estrogen levels in ovarian tissue by interfering with estrogen-synthesizing and metabolic enzymes such as aromatase and estrogen receptors signalling pathways [34].

Androgens play an important role in healthy female sexual function, especially in stimulating sexual interest and maintaining desire [35]. Testosterone initiates sexual activities and proliferates sexual desire and behaviour. In addition, testosterone is essential in modulating clitoral and vaginal physiology to facilitate genital lubrication, sensation, and engorgement [36]. The greatest decline in circulating testosterone occurs during the late reproductive years [37]. Lack of testosterone has been reported to contribute to low libido and reduced sexual pleasure characterised by low sexual motivation, fatigue, distress, and overall reduction in the sense of well-being [33‐35].

Oral and transdermal testosterone delivery has been shown to improve self-reported sexual satisfaction among premenopausal and postmenopausal women with low libido [36, 37]. A recent report has also evidenced the use of testosterone therapy to improve components of female sexual dysfunction [38]. Thus, the baseline sexual issues reflected by the MRS score in the present study can be dedicated to the lower normal range of testosterone. The increased total testosterone and free testosterone level after FHE supplementation might have also resulted in the improved sexual functions and libido.

Testosterone levels decline with age prior to menopause [39, 40]. There is ∼ 50% fall in both total and free testosterones between the ages of 20 and 40–45, with only a very slight fall in circulating concentrations thereafter (Fig. 1). In a study on 149 healthy premenopausal women having no low libido complains and regular cycles, it was shown that a statistically significant decline for each of free testosterone, dehydroepiandrosterone sulfate (DHEAS), androstenedione and Dihydrotestosterone (DHT) occur with aging [41]. Testosterone can be converted to either DHT or estradiol by the enzymes 5α-reductase and aromatase, respectively [42]. Dehydroepiandrosterone (DHEA) is the principal precursor of both androstenedione and testosterone androgens and 50% of DHEA is produced in the adrenal glands and 20% from the ovaries; 30% is derived from DHEAS that circulates in the blood [43]. During post-menopause, up to 60% of DHEA tend to decline, resulting in hypoandrogenism which can affect the normal sexual response in women [44].

The molecular mechanism behind the beneficial effect of FHE can be mainly attributed to its protodioscin content, a furostanolic saponin molecule having a significant structural similarity with DHEA. It was shown that protodioscin can be converted to DHEA [45], which further gets converted to testosterone and estradiol. Aromatase is involved in the conversion of testosterone to estradiol [46]. Zhou et al. have reported a significant increase of 17β-Hydroxy Steroid Dehydrogenase (17β-HSD), 3β- Hydroxy Steroid Dehydrogenase (3β-HSD) and aromatase mRNA levels when female rats were treated with DHEA [47]. The enzymes 17β-HSD and 3β-HSD are important in the synthesis of steroid hormones such as testosterone and estradiol which are involved to activate the Hypothalamic-Pituitary-Gonadal (HPG) axis by binding with estrogen receptors [27, 28]. Trigonelline, yet another major component in FHE has also been proven to enhance the estrogen level by some unknown mechanisms [48].

In women, abnormally high concentration of testosterone has been associated with polycystic ovary syndrome (PCOS) and ovarian cancers [49]. Serum levels of testosterone has been suspected in the etiology of breast cancer of postmenopausal women [50]. Most testosterone values in PCOS will be ≤150 ng/dL (≤ 5.2 nmol/L) [49], and in ovarian or adrenal tumour, it is shown to be of ≥200 ng/dL (≥ 6.9 nmol/L). The enzyme like ovarian aromatase activity is lower under PCOS conditions [51]. This may limit the conversion of testosterone to estradiol as well. So, the consumption of fenugreek extracts by women having PCOS conditions have to be careful, though earlier study has reported the beneficial effects of fenugreek under PCOS condition [52]. However, the role of phytoestrogens is ambiguous and they bind weakly to estrogen receptors and can either produce or inhibit estrogen effects [53]. In the present study, no overproduction of hormones has been observed with FHE intake, probably due to the active feedback mechanism in healthy women, which warrants further study on healthy participants. Since, estradiol is known to increase the concentration of serotonin and modulate its action, the effects of FHE on serotonin pathways also can be investigated to check the beneficial effects of FHE in menopausal discomforts and sexual issues.

In summary, supplementation of FHE at 250 mg × 2 per day for 42 days did not produce any side effects, adverse events or significant changes in both the haematological and biochemical parameters in young menstruating women. Further analysis indicated no detrimental effect on hormonal balance. The enhancement observed for estradiol and testosterone concentrations were within the safe reference range. The molecular mechanism of estrogenic effect can be attributed to the protodioscin content in FHE, since protodioscin can be converted to DHEA and further to testosterone and estradiol by the action of aromatase. The present study showed that FHE helps to maintain normal hormonal balance and offered a significant reduction in sexual problems and irritability scores among the participants.