Flax: Just the Facts Please

by Jeff Novick, M.S., R.D., L.D./N.

Flaxseeds have become very popular lately, because they are a rich source of the omega-3 essential fatty acid, also known as Alpha Linoleic Acid (ALA). Because of its link to good health, flaxseed is fast becoming a new food in many diets. Recently, two more studies have shown some additional benefit to flaxseed in disease prevention. Along with the news and increased use has also come some myths and some misunderstanding.

Flax is a blue flowering crop grown on the Prairies of Canada for its oil-rich seeds. The seeds of flax are tiny, smooth and flat, and range in color from light to reddish brown. Cultivated flax, L. usitatissimum, is of two types: one is grown for the seed and the other for fiber production. In North America, it is primarily the oilseed varieties which are produced commercially. They serve a variety of purposes, including baking and other food uses. Flax has been grown since the beginnings of civilization, and people have eaten flaxseed since ancient times. The first recorded uses of flax come from Southern Mesopotamia where flax was grown as long ago as 5,000 B.C. In the succeeding millennia, flax spread across Europe, Africa, Asia and finally to North America.

So, what's the "buzz" on flax?

Recent scientific reports point out that flaxseed can have a positive influence on everything from cholesterol levels to constipation to cancer and heart disease. Scientists at the American National Cancer Institute singled out flaxseed as one of six foods that deserved special study.

Some benefits of flaxseed

Relief from constipation

Eating 50 grams of flaxseed per day helped increase the frequency of bowel movements and the number of consecutive days with bowel movements in a group of older Canadian adults.

A lower risk for heart disease

Total cholesterol levels dropped 9 percent and LDL (the “bad” cholesterol) decreased 18 percent when a group of nine healthy women ate 50 grams of milled flaxseed a day for four weeks along with their regular diets, according to a report from the University of Toronto.

In a similar study with men and women, 50 grams of flaxseed lowered total cholesterol and showed a constant trend of about 11 to 16 percent lower serum lipids (fat in the blood).

Cancer prevention

Lignans, a type of fiber, and alpha-linolenic acid are found abundantly in flaxseed. Population studies of diet and disease risk suggest an anticancer role for flaxseed. Long-term studies of flaxseed effects in women with breast cancer are underway.

Recently two studies lend further support to the flax-seed/cancer prevention issue. The first is in relation to prostate cancer. The small pilot study was reported in the July issue of Urology (Urology 2001;58:47-52).

Dr. Wendy Demark-Wahnefried, from Duke University Medical Center, Durham, North Carolina, and colleagues studied 25 patients with prostate cancer who were about to undergo a prostatectomy. The patients were placed on a diet in which only 20% of total calories came from fat. In addition, patients received 30 g/day of ground flaxseed.

Over an average of 34 days, the subjects experienced a significant decrease in mean total testosterone, free androgen index and serum cholesterol. In addition, men who had a Gleason sum score of 6 or less before starting the diet showed a trend toward decreased PSA.

When the investigators looked at the prostates after prostatectomy, they found that prostate cancer cells were dividing much less rapidly and were self-destructing much more quickly in the treatment subjects compared with matched controls.

The researchers are unsure which part of the diet produced this cancer-fighting effect. However, Dr. Demark-Wahnefried said that in cell-culture studies in which prostate cancer cells were exposed to the lignans from flaxseed, they found significant decreases in cell growth. “It looks like these lignans may be responsible for the results we saw,” she added. “If there is a synergistic effect [with] the low-fat diet portion of the diet, it is unknown at this time.”

Dr. Demark-Wahnefried noted that although this was a small pilot study, the findings were compelling. “We will be launching a larger study in January comparing the effects of a low-fat diet with and without flaxseed supplementation.” Dr. Demark-Wahnefried and colleagues hope to be able to develop a diet that will retard prostate cancer. In addition, they are working toward using this strategy to prevent prostate cancer. “If these results hold, maybe 10 years down the road we will be testing this diet as a preventative to prostate cancer,” she said.

The second recent study is in relation to breast cancer and was presented last week at the annual meeting of the American Chemical Society in St. Paul, Minnesota, and showed that flaxseed can help protect post-menopausal women from breast cancer.

In the study, funded by the National Cancer Institute of the National Institutes of Health, twenty-eight postmenopausal nuns from a convent in central Minnesota took daily supplements of zero, 5 or 10 grams of ground flaxseed in seven-week cycles over the course of a year. “We don't know exactly how flaxseed does what it does. But we do know that it is considered to be the most concentrated food source of lignan,” said Dr. Joanne Slavin, lead investigator and professor of nutrition and food science. “Lignan appears to lower estrogen in humans by inhibiting enzymes that are involved in estrogen synthesis.”

Flaxseed provides 75 to 800 times more plant lignans, a type of phytoestrogen, than most other plant sources. Phytoestrogens are compounds that appear to interfere with estrogen metabolism in animals and humans.

The 5- and 10-gram groups showed a significant decrease in estrogens common to postmenopausal women, estrone sulfate and estradiol.

Some research suggests a correlation between estrogen metabolism and an increase of the chemical markers in the blood associated with development of breast cancer. “Since previous studies show that increased levels of estrone sulfate and estradiol may increase a woman's risk of developing breast cancer, reducing levels of these hormones could be protective against breast cancer,” Slavin said.

“The results are encouraging. Flaxseed appears to change the way that estrogen is metabolized by the body, making the metabolized product less estrogenic,” said Dr. Lillian Thompson, professor of nutrition science at the University of Toronto. “Estrogen is known to promote tumor growth. So the reduction of the estrogenic effect can be beneficial.”

Additional benefits of flaxseed

Flax and arrhythmia

Flaxseeds are the richest source of omega-3 fatty acids. These fats appear to enhance the mechanical performance and electrical stability of the heart and to protect against fatal arrhythmias. The mechanism of action likely includes modifying the fatty acid composition of cell membrane phospholipids, affecting cell signaling and controlling ion transfers across the cell membrane (Journal of Nutrition, 1997; 127:383-393).

Flax, inflammation, heart disease and the immune system

Flaxseed has been shown to reduce many of the markers of systemic inflammation, including pro-inflammatory eiconosoids, cytokines, and platelet activating factors. Flaxseed may help reduce coronary heart disease and stroke by reducing blood cholesterol levels and by retarding the progression of arteriosclerosis by reducing inflammatory responses. This reduction in pro-inflammatory factors, flaxseed may show benefit in many “hyper-stimulated” immune diseases such as rheumatoid arthritis, psoriasis, multiple sclerosis, and systematic lupus, or erythmatosis.

Questions and Answers about Flaxseed

Q Where can I buy flaxseed?

A You can buy whole flaxseed and packaged ground flax seed at many bulk food and health food stores. Conveniently, many supermarkets are also selling flaxseed in their bulk food sections. Check your local stores, as more outlets are carrying flaxseed now than ever before. This trend will continue as flaxseed becomes a more popular food item.

Q Which is better for me, whole or ground flaxseed?

A Ground flaxseed provides more nutritional benefits than does whole seed. That's because flaxseeds are very hard, making them difficult to crack, even with careful chewing. Grinding flaxseeds breaks them up, making them easier to digest when eaten. Then the body can profit from all that flax goodness. If whole flaxseeds remain unbroken, they may pass undigested through the body, reducing the nutritional advantage of eating flaxseed in the first place.

Q How can I grind the seeds?

A Flaxseeds are easy to grind, and you likely have the right tool in your kitchen. Grind flaxseeds at home using a coffee grinder, food processor or blender. Like coffee beans, you can grind flaxseeds coarsely or finely and if using in cooking, most recipes call for finely ground flaxseed.

Q What is the difference between brown flaxseed and golden or yellow flaxseed? Is one better than the other?

A No, one flaxseed is not better for you than another. Brown flaxseeds provide the same nutritional benefits as golden (or yellow) ones. Both brown and golden flaxseeds have plenty of lignans and dietary fiber, and both contain more than 50 percent alpha-linolenic acid. This is an omega-3 fat which offers you health and heart fitness. While some people may prefer yellow-colored seed, brown flaxseeds add the same nutrition to your diet as do golden ones. This means you can choose your flaxseed freely. Brown flaxseed may be more commonly found than golden, as more brown than golden flaxseed is grown commercially.

Note: There is another yellow seed that looks like flax, but is not flax. It is most likely solin seed, a crop developed from flax. Solin seeds do NOT provide the same nutritional benefit of flaxseeds. Solin seeds contain less than one-tenth of the alpha-linolenic acid found in flaxseeds. Thus, the important omega-3 advantage of flax is missing in solin.

Q How should I store flaxseed and how long will it keep?

A Whole flaxseed – whole flaxseed comes with Nature's own finest packaging – its natural hard hull keeps it fresh. You can store clean, dry, good quality whole flaxseed at room temperature for up to a year. Some people keep a jar of flaxseed handy on their kitchen counter.

Ground flaxseed – Any food that is high in vegetable fat requires some care in handling and storing. Once you grind flaxseed, there is greater risk of it developing an off-flavor and taste. That's why it's best to grind whole flaxseed as you need it. This ensures its freshness. After grinding, you should refrigerate it in an airtight, opaque container. Ground flaxseed handled this way will keep for up to 90 days. If you grind up an entire bag, store ground flaxseed in the freezer to keep fresh for a longer period of time.

Q Does flax contain gluten?

A Flax contains no gluten.

Q What's the easiest way to use it?

A Simply add the ground flaxseed to your morning oatmeal or other cereal. If you do any baking, flaxseed can be added to many baked products. You can also mix with chopped apple or mashed banana or mix with orange juice and pour over a salad. Personally, I blend whole flaxseeds in a fruit smoothie each morning.

Q What about flaxseed oil and/or flaxseed oil supplements?

A I do not recommend the use of flaxseed oil or flaxseed oil supplements. Like all oils, flaxseed oil is a concentrated source of calories. Also, there are other benefits to consuming the whole flaxseed that would not be available in the oil. One of these is a type of fiber found in flaxseeds called lignans. Lignans have been shown to have anticancer effects and are associated with a reduced risk of breast cancer. Additionally, flaxseeds are a good source of iron, zinc, calcium, protein, potassium, magnesium, Vitamin E and folate. These important nutrients play many beneficial roles in health maintenance and disease prevention. Flaxseed oil is pure fat and virtually void of all or most of these nutrients (except for vitamin E). Flaxseed oil is also a Poly-Unsaturated fatty acid (PUFA), and there is evidence that extracted PUFA oils can suppress the immune system, and possibly increase the growth rate of certain cancers and/or tumors. If you want the benefit of flax, eat the seed and avoid the oil.

Q How many calories are in flaxseed?

A 1 tablespoon of whole flaxseed (11 grams) contains about: 50 calories, 2.5 grams of protein, 3.5 grams of fiber, 23 mg of calcium, 33 mcg of folate, and 2.5 grams of omega-3. Although flaxseed is over 82% fat, over half (57%) of the fat in flaxseed is in the form of the omega-3 essential fatty acid.

Q Is there any research linking flaxseed oil to cancer?

A Research from Charles Myers, M.D., at the University of Virginia Medical School in Charlottesville showed that flaxseed oil causes a 300% increase in the growth of prostate cancer cells. Dr. Myers said, “It is the most powerful stimulus we know of for prostate cancer cells.” This information appeared in an article in the February 2000 issue of his Newsletter, Prostate Forum. I wrote to him personally and was sent the following references.

PK Pandalai, et al. “The effects of omega-3 and omega-6 fatty acids on in vitro prostate cancer growth” Anticancer Res 16: 815-820, 1996

E Giovannucci, et al. ”A Prospective study of dietary fat and risk of prostate cancer” Journal National Cancer Institute 85: 1571-1579, 1993.

P Gann, et al. “Prospective study of plasma fatty acids and risk of prostate cancer” Journal National Cancer Institute 86: 281-286, 1994

SO Anderson, et al. “Energy, nutrient intake, and prostate cancer risk: a population-based case-control study in Sweden” International Journal of Cancer 68: 716-722, 1996

PA Godley, et al. “Biomarkers of essential fatty acid consumption and risk of prostate cancer carcinoma” Cancer Epidemiology Biomarkers and Prevention 5:889-895, 1996

S Harvei, et al. “Prediagnostic level of fatty acids in serum phospholipids: omega-3 and omega-6 fatty acids and the risk of prostate cancer” International Journal of Cancer 71: 554-551, 1997

He says that while there is no benefit shown to flax oil, these studies do show a negative effect. He also states that the whole flaxseed may offer some benefit.

Q Are there any downsides to consuming the whole seed?

A Yes. Like all nuts and seeds, flaxseed is very high in calorie density. Therefore, if we are going to use flaxseed, we must do so in moderation and be careful about the portion size. 1 tablespoon of whole flaxseed, or 1-1/2 tablespoons of ground flaxseed will provide an adequate amount of the omega-3 fatty acids and has only 50 calories. I wouldn't recommend anyone to consume more then 2 tablespoons of whole flaxseed or 3 tablespoons of ground flaxseed in a day.

In summary, flaxseeds have many nutritional benefits and can be a valuable addition to a healthy diet. If you are someone who doesn't consume any fish, or doesn't eat enough green leafy veggies, then flaxseed is a vitally important source of omega-3 fatty acids for you. But remember, go easy on the flax, a little goes a long way.