Flaxseed Reduces Cholesterol in Postmenopausal Women
Ground flaxseed added to the daily diet of postmenopausal women lowers cholesterol levels, according to a recent study in The Journal of Clinical Endocrinology and Metabolism (2002;87:1527–32).
The risk of cardiovascular disease increases dramatically after menopause. Total cholesterol and low-density lipoprotein cholesterol (LDL, or “bad” cholesterol) rise and protective high-density lipoprotein cholesterol (HDL, or “good” cholesterol) drops when estrogen diminishes. Although hormone replacement therapy can slow the progression of osteoporosis and alleviate the symptoms of menopause, such as hot flashes and mood swings, its role in preventing cardiovascular disease has recently come into question. A family of medications known as statins are often used by doctors to lower cholesterol and improve lipid levels. Although statins have been shown to lower the risk of developing heart disease, in rare cases their use has been linked to liver damage, ranging from mild increases in liver enzymes (markers of liver damage measured in the blood) to acute liver failure, and therefore people taking them should be monitored carefully.
A number of nutritional measures, such as increasing dietary fiber and decreasing saturated fat intake, can improve the levels of cholesterol and other blood lipids. Studies have also demonstrated the cholesterol-lowering effects of phytoestrogens, plant components that are structurally similar to estrogen.
Soybeans are rich in a type of phytoestrogens called isoflavones. The beneficial effects of soy and isoflavones on cholesterol are well documented and many doctors frequently recommend increasing soy foods in the diet to reduce risk of cardiovascular disease. Flaxseeds are exceptionally rich in another type of phytoestrogens known as lignans and they also contain other components that could contribute to their health benefits, including omega-3 fatty acids and dietary fiber. They have become an increasingly popular dietary supplement, and several studies have borne out their cholesterol-lowering properties.
This recent study examined the effect of flaxseed on cholesterol and lipid levels as well as markers of bone breakdown in postmenopausal women. Thirty-six postmenopausal women were randomly assigned to consume either 40 grams (about 5 tablespoons) of ground whole flaxseed or a wheat-based powder (similar in texture and fiber content) with their regular diet for three months. All of the women were given 1,000 mg of calcium and 400 IU of vitamin D daily during the trial. Cholesterol and blood lipid levels, as well as blood and urine markers for bone loss, were measured before and at the end of the trial. Total cholesterol was significantly reduced in the women who ate ground flaxseed but those who ate the wheat-based food had no significant change. Furthermore, blood levels of non-HDL cholesterol and apolipoprotein B, both closely associated with cardiovascular disease, were significantly reduced in the flaxseed group but not in the wheat group. None of the markers for bone loss changed significantly in either group.
The results of this study are consistent with those of other studies examining the effects of ground flaxseed on total cholesterol. Although a statistically insignificant reduction of only 4.7% in LDL cholesterol was measured in this study, a previous study by the same researchers measured a pronounced drop of 14.7% in LDL cholesterol with a flaxseed supplement. The difference between the two studies was that the ground flaxseed was consumed raw in the new study, but was baked into bread or muffins in the earlier study. The authors suggested that heating of flaxseed in the baking process might change some of its beneficial components into forms more available to the body.
A number of studies have found that isoflavones, the primary phytoestrogens in soy, can slow the loss of bone that follows menopause and results in osteoporosis. This study demonstrated no change in bone loss with ground flaxseed supplementation, suggesting that lignans, the phytoestrogens in flaxseeds, do not have the same properties on bone as isoflavones.
Maureen Williams, ND, received her bachelor’s degree from the University of Pennsylvania and her Doctorate of Naturopathic Medicine from Bastyr University in Seattle, WA. She has a private practice in Quechee, Vermont, and does extensive work with traditional herbal medicine in Guatemala and Honduras. Dr. Williams is a regular contributor to Healthnotes Newswire.
Copyright © 2003 Healthnotes, Inc. All rights reserved. Republication or redistribution of the Healthnotes® content is expressly prohibited without the prior written consent of Healthnotes, Inc. Healthnotes Newswire is for educational or informational purposes only, and is not intended to diagnose or provide treatment for any condition. If you have any concerns about your own health, you should always consult with a healthcare professional. Healthnotes, Inc. shall not be liable for any errors or delays in the content, or for any actions taken in reliance thereon. Healthnotes and the Healthnotes logo are registered trademarks of Healthnotes, Inc.