In a hot-flash study, doctors noted that women used to treat hot flashes with synthetic hormone replacement therapy (HRT) until studies showed that HRT increased the risk of breast cancer. Whole flaxseed contains phytoestrogens, which act like estrogen in the body and is the reason doctors chose flaxseed for this pilot study.
Researchers recruited 30 women who were not taking HRT, and who had an average of two hot flashes per day for at least the past 30 days. All of the women took 40 grams of crushed flaxseed per day for six weeks. At the end of the study, the women reported an average of 57% less-severe hot-flash symptoms and 50% fewer hot flashes per day. About half the women reported mild or moderate bloating and one-quarter reported mild diarrhea. The doctors concluded that flaxseed reduced hot flashes and suggested a placebo-controlled study to confirm these findings.
In a blood pressure study, doctors noted that flaxseed contains alpha-linoleic acid (ALA), an omega-3 fatty acid which protects the heart and wanted to test ALA against some of the risk factors for cardiovascular disease (CVD). Researchers recruited 59 middle-aged men whose blood-fats were out of balance, which is a risk factor for CVD and high blood pressure. The men took flaxseed oil containing 8 grams of ALA per day or a placebo of safflower oil containing 11 grams of linoleic acid (LA)—an omega-6 fatty acid—per day for 12 weeks. At the end of the study, compared to the LA group, the flaxseed oil group had significantly lower systolic and diastolic blood pressure, which doctors said may be part of the reason omega-3s reduce risk for CVD.