Flax holds promise as anti-cancer agent

In flaxseed, nature’s well-stocked kitchen has a potentially effective anti-cancer agent and cholesterol fighter.

“There is a spectrum of interest in flaxseed ranging from marginal to fanatical,” says Dr. David Jenkins, endocrinologist, U of T professor of medicine and nutrition sciences, and Toronto’s renowned pioneer in high-fibre, low-fat foods.

Flaxseed, also known as linseed, looks like a flattened, brown or golden sesame seed, is grown in Manitoba and Saskatchewan, and up until recently, was used principally for its oil.

One of a growing list of foods, like tea and garlic, currently under investigation and often called “functional foods” or “designer foods” or even “nutraceuticals,” flaxseed is proving promising in its potential prophylactic and therapeutic properties, especially with cancer and heart disease.

University of Toronto scientist Dr. Lilian Thompson and Toronto Hospital oncologist Dr. Paul Goss are on the cutting edge of flaxseed research.

In her groundbreaking research in the department of nutritional science, Thompson has found flaxseed to be a potent source of lignans, containing between 75 and 800 times as many as 68 other fruits and vegetables.

Two lignans — enterlactone and enterodiol — are vital to the reduction of breast cancer tumor growth.
In laboratory studies, she has discovered that lignans can reduce the growth of breast cancer in rats by more than 50% and they can also reduce the incidence and number of tumors.

“The lignans are a more effective component of flaxseed than the oil,” Thompson adds. “But this work has only been done in experimental animals and it is really too early to say if its effects will be mirrored in humans, though it seems encouraging.”

Lignans are exciting the breast cancer community because they may benature’s version of tamoxifen, the world’s most widely used breast cancer drug.

Tamoxifen has been used for 20 years to treat advanced breast cancer, to prevent the spread of breast cancer, the occurrence of new tumors at the old site or new tumors in the other breast.

“Tamoxifen has been established as a living insurance policy for women who have developed breast cancer,” says Goss, a breast cancer specialist. “Now, it is being tested as a preventative of breast cancer. It is being given to healthy women, but it does have side effects.”

If lignans prove to do what tamoxifen can do, it could be a much safer alternative.

Similar in structure to tamoxifen, lignans in flaxseed seem to interfere with the actions of estrogen — making them anti-estrogens.

Lignans are also aromatase inhibitors, which prevent the synthesis of estrogen and which are involved in the propagation and proliferation of cancer cells, he explains. Goss has pioneered research into aromatase inhibitors, new drugs now being used to treat breast cancer.

Lignans also inhibit angiogenesis, the growth of new blood vessels within tumors, which means they can retard the growth of tumors, since tumors need blood vessels to grow and spread.

Currently, Thompson and Goss are collaborating on an important study with women who have recently been diagnosed with breast cancer.

Over two years, by giving 120 women flaxseed between their biopsies and their surgery, they hope to show that the tumors are different. That the flaxseed has produced an anti-cancer effect, slowed cell growth, and stopped dividing and killed cancer cells.

“Lignans are providing us with a model of what is needed. You have to remember that natural products and drugs aren’t dissimilar,” explains Goss.”In fact, many natural products are drugs. However, flaxseed is much less potent than the drugs we use like tamoxifen. It just hasn’t the same power.”

When you consider the epidemiology of breast cancer, where it occurs in the world and why, Goss notes that though Asian populations have a low breast cancer incidence and typically eat a high-fibre, low-fat diet, in Finland, where breast cancer incidence is also low, the diet is high in fat and also high in flaxseed.

“That suggests you may not have to eliminate fat, just keep eating flaxseed,” he says. “It may turn out that you need to eat it all of your life. However, it can’t hurt to start eating it now. After all, it’s a fibre, with all the advantages of a fibre.”

Among those advantages is the alpha linolenic acid in flaxseed which can lower cholesterol and reduce the blood’s clotting tendency which contributes to the lowering of heart attack risk. Besides, as a soluble fibre, it keeps you regular.

“In healthy people„ flaxseed can lower cholesterol by 7%, and in people with higher cholesterol, the more benefit you have,” states Dr. Stephen Cunnane, a U of T associate professor who has researched flaxseed’s cholesterol fighting properties.

To be effective, Cunnane suggests you eat between 5 and 25 grams a day, though you can eat as much as 50 grams of ground flaxseed daily, which can be put into muffins, is found commercially in Red River Cereal and some breads.

If you choose to buy it, you’ll find it in health food stores and you must grind it — a coffee grinder is best — and store it in the freezer. Ground flaxseed, which has a nutty flavor, has a shelf life of two to three weeks.

“There are no significant side effects with eating flaxseed, besides stomach distension,” warns Cunnane. “And you can get gassy.”

Excerpted from an article by Sandy Naiman appearing in the Toronto Sunday Sun, April 30, 1995.