Flaxseed, also called linseed, is grain available as flour, meal, and seeds. Flaxseed is in some multigrain breads, cereals, breakfast bars, and muffins. Toasted flaxseed can be sprinkled into salads, yogurt, or smoothies. Flaxseed is a good source of lignans, plant-based compounds that have a weak estrogen effect.
Because of this weak estrogen effect, doctors thought flaxseed may help ease hot flashes and other menopausal symptoms. Hot flashes and night sweats are often called vasomotor symptoms.
A study found that women who ate fiber bars with added flaxseed got no more relief from hot flashes than women who ate the same fiber bars without flaxseed. The research is published in the Journal of Clinical Oncology and presented at the 2011 annual meeting of the American Society of Clinical Oncology (ASCO).
In this study, 188 postmenopausal women ate a fiber bar every day for 6 weeks. Half the women ate a fiber bar that had 410 milligrams of flaxseed lignans in it. The other women ate an identical fiber bar with no flaxseed (the placebo fiber bar). All the women rated their hot flashes and other vasomotor symptoms and overall quality of life at the start and end of the study.
Both groups of women said their vasomotor symptoms eased about the same amount during the study's 6 weeks:
- Women who ate the flaxseed fiber bars had a 33% drop in their vasomotor symptom scores from the beginning to the end of the study.
- Women who ate the placebo fiber bars had a 29% drop in their vasomotor symptom scores from the beginning to the end of the study.
The results mean that flaxseed offered the same relief as the placebo for menopausal vasomotor symptoms -- there was no difference between the flaxseed and the placebo. The women who ate the flaxseed fiber bars also didn't have better quality of life than the women who ate the placebo fiber bars.
Although this study found that flaxseed didn't help ease hot flashes and other vasomotor symptoms, flaxseed may offer other health benefits.
Since the 1950s, some doctors have thought that flaxseed may help reduce the risk of breast cancer.
Because flaxseed lignans have a weak estrogen effect, the lignans may be able to replace the body's natural estrogen in a breast cell's estrogen receptor. Flaxseed lignans in the estrogen receptor would block the effect of the natural estrogen and reduce the risk of hormone-receptor-positive breast cancer that needs estrogen to grow. Most of the results on the potential protective effect of flaxseed have come from a few small studies on animals. More and larger studies on the effects of flaxseed in people are needed so we can know exactly how flaxseed may help reduce risk.
Flaxseed also can help keep cholesterol down and bowels healthy. The oil in flaxseed, alpha-linoleic acid, is an omega-3 essential fatty acid. Flaxseed is also high in fiber.
If you'd like to add flaxseed to your diet, start with a small amount and make sure you drink plenty of water. The lignans are concentrated in the hull (the outer husk or shell) of the flaxseed. Grinding the seeds makes it easier for your body to absorb the lignans. The U.S. Department of Agriculture has no daily recommended amount for flaxseed. Many registered dietitians advise eating 1 or 2 tablespoons of ground flaxseed meal daily.
If you're having troublesome hot flashes and other vasomotor symptoms related to natural menopause or because of breast cancer treatment, you might want to ask your doctor about options to ease these side effects. Several prescription medicines can help. There are also other steps you can take to help avoid and ease hot flashes. Visit the Breastcancer.org All About Hot Flashes page to learn more about hot flashes and how to manage them.