Evaluation of the Efficacy of Flaxseed Meal and Flaxseed Extract in Reducing Menopausal Symptoms

The objective of this study was to evaluate the efficacy of flaxseed meal and flaxseed extract in reducing climacteric symptoms of menopausal women.  Ninety menopausal women were randomly distributed into three study groups:  group I received 1g per day of flaxseed extract containing at least 100 mg of secoisolariciresinol diglucoside (SDG), group II received 90 g per day of flaxseed meal containing at least 270  mg of SDG, and group III received 1 g per day of collagen (placebo group).  Subjects were assessed for menopausal symptoms by the Kupperman index at the beginning and at the end of the 6 months of treatment.  Subjects were also assessed for endometrial thickness and vaginal cytology.  The Kupperman index values at the beginning and end of the treatments were analyzed using the paired t-test.  Both the flaxseed extract (p .007) and the flaxseed meal (p .005) were effective in reducing the menopausal symptoms when compared with the placebo control (p .082).  Alternatively, the changes in Kupperman index were also computed and submitted to analysis of variance.  In this case, no significant differences were found (P=.084) although the data indicate a decreasing tendency for the Kupperman index by both the flaxseed extract and the flaxseed meal groups.  Neither the flaxseed extract nor the flaxseed meal exerted clinically important estrogenic effects on the vaginal epithelium or endometrium as revealed by the absence of changes in the blood levels of follicle stimulating hormone and estradiol, as well as in the endometrial thickness, and vaginal epithelial maturation value.  No serious adverse events related to the treatments were reported.  Although the results of the present study do not allow an unequivocal conclusion about the action of flaxseed on the menopausal symptoms, they suggest that it could be premature to conclude that no such action exists.  Clearly the matter still deserves further experimental attention. (Authors abstract)

The synthetic hormone replacement therapy (HT) is used during menopause to prevent symptoms and diseases related to menopause.  This type of therapy, however, is directly linked to risks, such as increased incidence of breast and endometrium cancer, thromboembolic complications, and strokes in hypertensive women.  So far the few studies evaluating the effectiveness of flaxseed in reducing menopausal symptoms have led to contradictory results, which indicate the need of new studies to assess the effectiveness of flaxseed and its lignans as alternative forms of treatment for menopausal symptoms.  Thus, the purpose of this study was to evaluate the effect of flaxseed (concentrated extract and whole meal) on the cell maturation index measured by vaginal cytology, on the endometrial hypertrophy signals assessed by trans-vaginal ultrasound, and on the subjective clinical symptoms evaluated by the Kupperman index in menopausal women.  The hot flashes symptom was also evaluated separately because it is the most frequent menopausal symptom and the primary reason for which women seed medical treatment. This study showed that flaxseed did not exert clinically important estrogenic effects on vaginal epithelium or endometrium. The phytoestrogens in general have antiproliferative action on hormone-responsive cancers, such as endometrium and prostate cancers; hence, its use is considered safe for the endometrium.  In agreement with previous studies using phytoestrogens, no significant increase in the circulating level of estradiol was observed.  In this respect, thus, the use of flaxseed (meal and extract) can be considered as safe. Although gastrointestinal complaints have been reported in this work, the number of adverse events occurring during treatment with flaxseed was low, comparable to that of the placebo.  Treatment with phytoestrogens is in general associated with a low incidence of adverse events and good adherence to treatment. Further research is necessary to expand these results. (Editors comments)