Flaxseed as a dietary supplement: A review from the Wake Forest Center for Botanical Lipids
We recently took a look at The Wake Forest University Center for Botanical Lipids website. This Center is one of five such dietary supplement research centers funded through the federal government’s National Institutes of Health–so this website represents our tax dollars at work!
The main goal of this new research center is to “determine the role of fatty acid based dietary supplements in the prevention and treatment of chronic human diseases associated with inflammation.” The center’s website also makes the point that “nearly 20% of Americans use dietary supplements, many of them botanicals, but scientific evidence for their safe and effective use in the prevention or treatment of human diseases has lagged behind the use of the products.”
Actually, we think the 20% estimate may be on the low side, especially if you include use of basic multivitamins; and certainly among groups with chronic conditions (such as osteoarthritis) the rate of supplement use is often higher than 20%. But we certainly agree that we need more scientific evidence about the effectiveness and safety of supplements, and we’re glad to know that the NIH has continued to fund such research, especially through its National Center for Complementary and Alternative Medicine (NCCAM) and its Office of Dietary Supplements (ODS).
OK, enough of the federal governmental acronyms, and back to the Wake Forest website. We’re pleased to see that it includes a user-friendly section with some publications easily understood by the general public (”Articles for Everyday People”). Here’s a sample from the piece entitled “The Use of Dietary Flaxseed for the Prevention of Human Disease”:
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Flaxseed (also called linseed) has been a part of the human and animal diet for thousands of years. It is the richest known plant source of omega-3 fatty acids - 58% of the total fat in flax is composed of alpha-linolenic acid (LNA); however, this fatty acid is a short chain omega-3 as opposed to the long chain omega 3s found in fish oil. A number of studies have shown that flaxseed does not replace fish oil in the diet because the conversion of LNA to the omega-3 fatty acids found in fish oil is very inefficient.
Flaxseed is also a minor source of the omega-6 fatty acid linoleic acid (LA), which makes up about 14% of the total fat content. LNA and LA are essential fatty acids, meaning they cannot be made in the body and instead must be present in the diet. LNA is thought to be necessary for the proper function of cell membranes and nerve cells. In addition to LNA, flaxseed also contains soluble and insoluble fiber and lignans, which are antioxidants and estrogen precursors called phytoestrogens.
Flaxseed provides a healthy balance of omega-3 and omega-6 fatty acids, which is thought to have beneficial effects on many diseases, especially those with a strong inflammatory component, such as inflammatory bowel disease, arthritis, asthma, gout, and lupus. Flaxseed oil has been used to treat burns, acne, eczema, rosacea, and other skin disorders, and it promotes healthy hair and nails. Flaxseed has been suggested to minimize nerve damage in degenerative diseases such as Parkinson’s disease and may guard against the effects of aging.
The lignans in flaxseed may also play a role in cancer treatment and prevention, especially in women with breast cancer. The phytoestrogens found in flaxseed are thought to act as “designer estrogens” and are a good supplement to regular therapy (1). In a study of women with breast cancer, those who consumed 25 grams of flaxseed oil per day saw a reduction in tumor growth compared to placebo controls (2). The LNA in flaxseed may decrease the risk of sudden cardiac death by stabilizing the electrical system of the heart and preventing potentially fatal irregularities in heart rhythm. In a study of more than 75,000 women, those who consumed more than 1.5 grams of flaxseed per day had a 46% lower risk of cardiac death than women who consumed less than 0.5 grams per day (3).
While most studies show a benefit of flaxseed oil, there have been studies which have not been positive. In 5 out of 6 epidemiological studies on prostate cancer, flaxseed was shown to increase cancer risk, and LNA is a strong growth stimulus in isolated prostate cancer cells (4). Neither of these effects has been seen with fish oil. In addition, recent studies suggest that flaxseed may increase the risk of macular degeneration or speed up the progression of the disease.
In a nutshell: flaxseed looks to be very interesting for breast cancer and cardiovascular disease, but not recommended when prostate cancer or prostate cancer risk is present.
Add comment April 11, 2008
