SAN ANTONIO — Flaxseed relieved vasomotor hot flashes in postmenopausal women in a randomized blinded crossover trial, Lorraine E. Turner, Ph.D., reported at the annual breast cancer symposium sponsored by the Cancer Therapy and Research Center.
Although the study wasn't conducted in women with a history of breast cancer, the observed benefits suggest that flaxseed could be a useful treatment alternative in such patients, who frequently experience hot flashes exacerbated by adjuvant chemotherapy and/or hormone therapy with tamoxifen, observed Dr. Turner of the University of Manchester, England.
The predicament breast cancer patients face with regard to hot flashes is that hormone therapy is the most effective treatment for these estrogen deficiency-related symptoms, but there is concern that such therapy might increase the risk of breast cancer recurrence.
Dr. Turner reported on 85 postmenopausal women who experienced at least five hot flashes and/or night-sweat episodes per 24 hours. They were randomized to 40 g/day of flaxseed food supplements or placebo for 3 months and then crossed over to the opposite treatment arm for another 3 months of therapy.
The median number of hot flashes dropped by 38% during flaxseed supplementation from a baseline of 208 per month, with placebo showing no significant effect. The decline in hot flashes correlated with a rise in enterodiol, enterolactone, and other urinary lignan markers. Lignans are a type of phytoestrogen abundant in flaxseed.
Laboratory work performed on a monthly basis showed that flaxseed supplementation was associated with significant reductions in serum FSH and Apo-A1, but no changes were seen in serum total cholesterol, triglycerides, growth hormone, LH, prolactin levels, or markers of bone turnover.
Nor was flaxseed associated with any thyroid function abnormalities. This is an important observation, because although soy isoflavones previously have been shown to reduce hot flashes while improving serum lipid profiles and enhancing bone mineral density, there is some evidence to suggest isoflavones can cause hypothyroidism, she said.
Dr. Turner's study was funded by the Food Standards Agency of the United Kingdom.