Flaxseed's therapeutic uses
Flaxseed, derived from the flax plant (Linum usitatissimum), is recognized for its potential therapeutic uses, particularly in promoting digestive health, cardiovascular wellness, and possibly offering cancer-preventive benefits. This small seed is rich in dietary fiber, which can help alleviate constipation and improve overall gut health, making it a favored option for managing digestive disorders such as irritable bowel syndrome and diverticulitis. Additionally, flaxseed contains alpha-linolenic acid, an omega-3 fatty acid that may support heart health by helping to lower cholesterol levels and blood pressure.
Some studies suggest flaxseed may also provide relief from menopausal symptoms and urinary issues associated with benign prostatic hyperplasia, though evidence on these uses is mixed. Furthermore, the lignans present in flaxseed exhibit phytoestrogenic properties, which could have implications for cancer prevention, particularly concerning hormone-dependent cancers. While flaxseed is generally considered safe for most people, caution is advised for pregnant or nursing women and those with a history of estrogen-sensitive cancers. As with any dietary supplement, it is essential to consult a healthcare professional before incorporating flaxseed into a health regimen, especially for individuals with specific health conditions such as diabetes or cancer.
Flaxseed's therapeutic uses
- DEFINITION: Plant product consumed for specific health benefits.
- PRINCIPAL PROPOSED USES: Constipation, heart disease, high cholesterol
- OTHER PROPOSED USES: Benign prostatic hyperplasia, blood pressure, cancer prevention, diverticulitis, dyspepsia, irritable bowel syndrome, liver disease, lupus nephritis, menopausal symptoms, skin inflammation
Overview
Flaxseed is the hard, tiny seed of Linum usitatissimum, the flax plant, which has been widely used for thousands of years as a source of food and clothing. There are a minimum of three flaxseed components with potential health benefits. The first is fiber, which is valuable in treating constipation. Flaxseed also contains alpha-linolenic acid, a type of omega-3 fatty acid similar to the omega-3 fatty acids found in fish oil but significantly different in other ways and perhaps offering some of the same benefits. Finally, substances called lignans in flaxseed have phytoestrogenic properties, making them somewhat similar to the isoflavones in soy. The oil made from flaxseed has no appreciable amounts of lignans, but it does contain alpha-linolenic acid.
Therapeutic Dosages
According to the European Scientific Cooperative on Phytotherapy, the usual dose of flaxseed for constipation is 5 grams (g) of whole, cracked, or freshly crushed seeds soaked in water and taken with a glassful of liquid three times a day. Effects begin in eighteen to twenty-four hours. Because of this time delay, it is recommended to take flaxseed for a minimum of two to three days. Children aged six to twelve years should be given one-half the adult dose, while children younger than age six years should be treated only under the guidance of a physician.
To soothe an upset stomach, some recommend soaking 5 to 10 grams of whole flaxseed in one-half cup of water, strain after twenty to thirty minutes, then drink. For painful skin inflammations, the recommended dose is 30 to 50 grams of crushed or powdered seed applied externally as a warm poultice or compress.
Like other sources of fiber, flaxseed should be taken with plenty of fluids, or it may worsen constipation. Also, it is best to start with smaller doses and then increase.
Uses and Applications
The fiber in flaxseed binds with water, swelling to form a gel that, like other forms of fiber, helps soften the stool and move it along in the intestines. One study found that flaxseed can help with chronic constipation in irritable bowel disease. German health authorities approve of the use of flaxseed for various digestive problems, such as chronic constipation, irritable bowel syndrome, diverticulitis, and general stomach discomfort.
Flaxseed may be slightly helpful for improving cholesterol profile, according to some studies. Purified alpha-linolenic acid or lignans alone have not consistently shown benefits. It may be the generic fiber and not the other specific ingredients in flaxseed that improve cholesterol levels. The ability of flaxseed to lower cholesterol, combined with its benefits for reducing blood pressure, indicate flaxseed may hold cardiovascular benefits.
Flaxseed, its lignans, and its oil have undergone a small amount of investigation for potential cancer prevention or cancer treatment possibilities. Flaxseed has shown some promise for treating kidney disease associated with lupus (lupus nephritis). Because it is believed to have soothing properties, flaxseed is sometimes used for symptomatic relief of stomach distress and is applied externally for inflammation of the skin. However, research on these potential uses is essentially nonexistent.
Although flaxseed is often advocated for the treatment of symptoms related to menopause, a sizable twelve-month study failed to find it more helpful than wheat germ placebo. Besides failing to improve immediate symptoms, such as hot flashes, flaxseed did not appear to provide any protection against loss of bone density. An earlier, much smaller study by the same researchers found it equally effective for menopausal symptoms as hormone replacement therapy, but because of the absence of a placebo group and the high rate of placebo response in menopausal symptoms, these results cannot be taken as indicating much. Another study tested flaxseed without comparing it with placebo and reported a 50 percent reduction in hot flashes. The researchers went on to state that this reduction in hot flashes was “greater than what would be expected with placebo,” a rather curious claim because menopausal women given a placebo typically experience almost exactly a 50 percent decrease in hot flashes.
In a preliminary double-blind trial of seventy-eight older men, flaxseed extract modestly improved the urinary symptoms associated with benign prostatic hyperplasia (prostate enlargement) after four months of treatment. The use of essential fatty acids in the omega-3 family has also shown some promise for the treatment of nonalcoholic fatty liver.
Scientific Evidence
Constipation. In a double-blind study, fifty-five people with chronic constipation caused by irritable bowel syndrome received either ground flaxseed or psyllium seed (a well-known treatment for constipation) daily for three months. Those taking flaxseed had significantly fewer problems with constipation, abdominal pain, and bloating than those taking psyllium. The flaxseed group had even further improvements in constipation and bloating while continuing their treatment in the three months after the double-blind part of the study ended. The researcher concluded that flaxseed relieved constipation more effectively than psyllium.
Cholesterol and atherosclerosis. Some human studies have found that flaxseed improves cholesterol profile. However, the benefits, if any, are very modest. For example, in a double-blind study of about two hundred postmenopausal women, the use of flaxseed at a dose of 40g daily produced measurable improvements in cholesterol profile, but the improvements were so small that the researchers considered them “clinically insignificant.” It has been claimed that flaxseed might also have a direct effect in helping to prevent atherosclerosis based on its lignan ingredients, but confirmatory evidence is lacking.
Cancer. Some evidence hints that flaxseed or its lignan components might have cancer-preventive properties. Observational studies and other forms of preliminary evidence suggest that people who eat more lignan-containing foods have a lower incidence of breast cancer and, perhaps, colon cancer.
The lignans in flaxseed are phytoestrogens, plant chemicals mimicking the effects of estrogen in the body: phytoestrogens hook onto the same spots on cells where estrogen attaches. If there is little estrogen in the body, for example, after menopause, lignans may act like weak estrogen. However, when natural estrogen is abundant, lignans may reduce the hormone’s effects by displacing it from cells. Displacing estrogen in this manner might help prevent those cancers that depend on estrogen, such as breast cancer, from starting and developing. (This is also, in part, how soy is believed to work in breast cancer prevention, although the phytoestrogens in soy are isoflavones.)
Some preliminary research indicates these lignans may also fight cancer in other ways, perhaps by acting as antioxidants. Animal studies using flaxseed and its lignans offer supporting evidence for a potential cancer-preventive or even cancer-treatment effect. Several found that one or the other inhibited breast and colon cancer in animals and reduced metastases from melanoma (a type of skin cancer) in mice. Test-tube studies have found that flaxseed or one of its lignans inhibited the growth of human breast cancer cells and that the lignans enterolactone and enterodiol inhibited the growth of human colon tumor cells. This preliminary research is promising, but much more is needed before any conclusions can be drawn. Although much of this anticancer work has focused on the lignans in flaxseed, one study also found that flaxseed oil, which contains no appreciable amounts of lignans, slowed the growth of malignant breast tumors in rats.
Safety Issues
Flaxseed is generally believed to be safe. However, there are some potential risks to consider. As with many substances, there have been reports of life-threatening allergic reactions to flaxseed.
Because of its potential effects on estrogen, pregnant or breastfeeding women should probably avoid flaxseed. One study found that pregnant rats who ate large amounts of flaxseed (5 or 10 percent of their diet) or one of its lignans, gave birth to offspring with altered reproductive organs and functions (in humans, eating 25g of flaxseed per day amounts to about 5 percent of the diet). Lignans were also found to be transferred to baby rats during nursing. Additionally, a study of postmenopausal women found that the use of flaxseed reduced estrogen levels and increased levels of prolactin. This suggests hormonal effects that could be problematic in pregnancy.
Flaxseed may not be safe for women with a history of estrogen-sensitive cancer, such as breast or uterine cancer. A few test-tube studies suggest that certain cancer cells can be stimulated by lignans, such as those present in flaxseed. Other studies found that lignans inhibit cancer cell growth. As with estrogen, lignans’ positive or negative effects on cancer cells may depend on dose, type of cancer cell, and levels of hormones in the body. Persons with a history of cancer, particularly breast cancer, should consult a doctor before consuming large amounts of flaxseed.
Flaxseed, like other high-fiber foods, may delay glucose absorption. This may lead to better blood sugar control, but it also may increase the risk of hypoglycemic reactions. Persons with diabetes should consult a doctor about appropriate use.
Finally, flaxseed contains tiny amounts of cyanide-containing substances, which can be a problem among livestock eating large amounts of flax. While normal cooking and baking of whole flaxseed or flour eliminates any detectable amounts of cyanide, it is theoretically possible that eating huge amounts of raw or unprocessed flaxseed or flaxseed meal could pose a problem. However, most authorities do not think this presents much of a risk in real life.
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