Examining Soy's Role In The Fight Against Breast Cancer

Does soy intake help prevent breast cancer?

In spite of what you may have heard, theres no easy answer to that question, which is at the heart of a long, ongoing debate. But a recently completed 10-year study from Japan reveals some promising new clues that could eventually lead to useful answers.

In the meantime, there is something that women can do right now that may help lower their risk of breast cancer considerably.

Soy is as soy does

Because the incidence of breast cancer in Japan is far lower than in western countries like the UK, and because the soy intake of Japanese women has historically been several hundred times higher than western women, a great deal of speculation has been devoted to the role that soy may play in preventing breast cancer.

By now, most HSI members are probably familiar with isoflavones - the bioactive plant chemicals that have oestrogenic activity. Found in legumes, grains, cabbage and soy products, isoflavones have been shown to play a part in lowering the risk of heart disease, and may help prevent osteoporosis. In addition, a number of laboratory studies have concluded that isoflavones may also curb the development of breast cancer.

In 1990, the Japan Public Health Centre (JPHC) launched the Prospective Study on Cancer and Cardiovascular Diseases. Nearly 22,000 women between the ages of 40 and 59 completed questionnaires that included dietary information. During a follow up period of 10 years, 179 of those women were diagnosed with breast cancer.

When researchers isolated statistics about the intake of isoflavone-rich foods (particularly soy foods and miso soup) and measured them against the breast cancer information, three results stood out significantly:

Consumption of isoflavone-rich foods and miso soup was associated with a decreased risk of breast cancer

Consumption of soy foods alone was NOT associated with a decreased risk of breast cancer

The decreased risk of breast cancer was strongest among postmenopausal women

So would women do well to add two or three bowls of miso soup (which is derived from soy) to their daily diets? The answer to that one might seem obvious, but its not.

Head em out, round em up

Dr. Seiichiro Yamamoto, the lead researcher of the JPHC study, cautiously told Reuters Health that the study doesnt provide enough evidence to recommend soy intake as a prevention against breast cancer. Nevertheless, he said that its not a bad idea to recommend women in western countries to eat soy and other isoflavone foods.

Unfortunately, Dr. Yamamoto may be unaware that soy products are not all the same the world over. HSI Panellist Dr Allan Spreen, has expressed his doubts about soy, saying, When you take the basic components of the soybean, and then add to that the modern procedures of cultivation and mass production, you have a highly processed food of dubious nutritional value.

For instance, some soy crops have been genetically modified (GM) to survive a constant saturation with weed killer. A normal soy plant will die when sprayed with the highly toxic weed killer. But a GM soy plant survives the spray, making it possible for farmers to use the herbicide liberally.

Japan, however, has shunned GM crops for the most part. So whats the difference between a Japanese soy bean and a UK soy bean thats been genetically modified and doused with a powerful herbicide? At this point no one knows for sure. But its easy to imagine that the nutrients in a UK soy bean may be compromised, to say the least.

Soy by any other name

The JPHC study showed that the consumption of isoflavone-rich foods and miso soup was associated with a decreased risk of breast cancer, but consumption of soy foods was not. This result reminded me of something else that Dr. Spreen has said about soy - and miso in particular:

The phytates on board (which can block absorption of both proteins and minerals) are only deactivated with soy thats been fermented. Tofu, textured soy protein and most other forms are anything but. Tempeh, miso, soy sauce made by the traditional method (most in the UK is not), and a few other forms are the only ones that qualify, and we dont see them much around here.

Miso! As usual, Dr. Spreen is ahead of the pack.

But you dont have to go anywhere near a soy bean (GM or otherwise) in order to get more isoflavones in your diet. Red clover has twice the amount of phytooestrogen isoflavones that soy has, but without any of the potential negatives of soy. In addition, red clover extract has traditionally been used to remove toxins from the body and to treat a variety of health problems, including chest congestion, chronic degenerative diseases, gout, psoriasis and eczema.

But a word of caution: studies have shown that red clover may thin the blood, so it should not be used by patients who are also taking an anticoagulant medication.

The debate about soy, isoflavones and their effect on breast cancer is far from over. Im certain that this JPHC study will lead to further studies on the subject, so Ill be on the watch for more information and will of course bring you updates in future e-alerts.