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Dec. 8, 2000 -- If you had just been diagnosed with breast cancer, you would be willing to do anything to slow tumor growth before your surgery, wouldn't you? Well, here's something that may get the job done, and it won't feel like work: eat a muffin (or something) that contains flaxseed oil.
If the data from a small Canadian study hold true, flaxseed oil may slow tumor growth.
Breast cancer activists have been interested in the potential benefits of flaxseed oil for some time. This substance is particularly rich in phytoestrogens. These are the plant precursors of estrogens and are being looked at on several fronts as a natural source of so-called "designer estrogens" or selective estrogen receptor modifiers (SERMs). Tamoxifen, which is used to reduce the risk of recurrence in women who have had breast cancer, is an example of a SERM.
At the San Antonio Breast Cancer Symposium this week, Canadian investigators presented findings that indicate flaxseed may be a helpful complement to conventional treatment for breast cancer. In their study, the investigators found that flaxseed oil's ability to reduce tumor growth is comparable to tamoxifen.
"This is the first time ever that a dietary substance has been shown to have a direct impact on the biology of human breast cancer," co-investigator Paul Goss, MD, tells WebMD. "We have a direct effect on human tumor cells from a dietary component. All the evidence is that eating brown flaxseed in your diet is a healthy thing to do. It is likely to be preventive of breast cancer and may also be preventive of colon cancer." He is the director of the breast cancer research program at Princess Margaret Hospital in Toronto and professor of medicine at University of Toronto. Collaborating on the study with him was Lillian Thompson, PhD, professor of nutritional sciences at University of Toronto.
Consumers have been buying flaxseed oil capsules at health food stores in North America for years, says Goss. However, more benefits are seen from eating ground flaxseed than from either using flaxseed oil capsules or from eating whole seeds.
While people in North America do not typically include flaxseed in their diets, it is commonly found in the diets of people in several parts of Europe, such as Scandinavia, and epidemiologists have seen its advantages from European-based studies, says Goss.
The 39 patients in the study ate a muffin daily. They were randomized to receive either a muffin containing 25 grams of flaxseed oil or a plain muffin for an average of five-and-a-half weeks.
Among 29 of the 39 women who ate both kinds of muffins, there were reductions in tumor cell growth in the flaxseed group compared to the group that ate plain muffins. All 29 women had gone through menopause. Urine tests after the study showed that the women taking flaxseed oil excreted a level of phytoestrogens higher than the group that ate the plain muffin, and higher than the overall group excreted at the beginning of the study. They saw no significant differences between the two groups' caloric and nutritional intake, and they observed no significant adverse effects.
The other 10 women had not gone through menopause. The researchers did not analyze the results in this group, because the group was so small.
For now, wait and see is probably the best response to these findings, Hillary Rutter, ACSW, tells WebMD. "There are women who have been interested in flaxseed oil for awhile," says Rutter, director of the New York Statewide Breast Cancer Hotline and Support Program, an information and advocacy group for breast cancer survivors. "However, I don't think we can draw conclusive evidence from the study, because there was a small number of women and a short follow-up period. However, there is evidence that we should study flaxseed oil further. It's positive that investigators are looking at ways to give women more control over health. If they can find benefits for women battling breast cancer or wanting to prevent it, it certainly needs to be studied."
And there may also be an additional bonus to taking flaxseed oil. It may help women who have excessive premenstrual breast tenderness. The same investigators studied 116 women with severe cyclical breast tenderness who were given either a flaxseed oil-containing muffin or a plain muffin daily. Although both groups reported relief, the flaxseed oil group reported significantly more relief.