The human body is a fantastic machine with a variety of defence mechanisms to protect itself against undesirable chemical intruders. A variety of enzymes are available either to convert these intruders into less harmful substances or to link up with them and eliminate them through the urine. These protective enzymes are cranked out by a cell's genetic machinery when receptors on the cell's surface are activated by the presence of potentially dangerous foreign substances.
Way back in the 1950s, researchers notes that substances that caused cancer triggered the release of protective enzymes, but that unfortunately, in many cases, the enzymes were unable to eliminate the carcinogen completely. It was clear, though, that some test animals fared better than others. Apparently, they had more efficient enzyme-producing systems. There are human parallels here also. Not every smoker develops lung cancer. Why not? Do the lucky ones produce more protective enzymes? And if so, can we foster this trait?
The fight against breast cancer
A clue came when researchers noted that after rats were exposed to a carcinogen, they were more resistant to the effects of a second carcinogen. They appeared to be protected by the enzymes their cells synthesized in response to the first attacker. Obviously, exposure to a carcinogen is not a method we can use to protect ourselves against other carcinogens. But what if there were substances that had a chemical similarity to cancer-causing agents but were themselves not dangerous? Might they not trick cells into generating protective enzymes? By the 1960s it had become apparent that this was a real possibility.
Chemicals in cabbage, as well as in other cruciferous vegetables (so-called because of the cross-shaped leaves) like broccoli, cauliflower and Brussels sprouts were found to stimulate the production or protective enzymes. Soon researchers focused on one specific compound that had aroused interest because of its potential in the fight against breast cancer, namely indole-3-carbinol.
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Excerpted from An Apple a Day: The Myths, Misconceptions and Outright Exaggerations about Diet, Nutrition and the Foods We Eat. Published by HarperCollins Publishers Ltd. Copyright 2007 by Dr. Joe Schwarcz. All rights reserved. Reprinted by permission of HarperCollins Publishers Ltd. Estrogen
The connection here is through estrogen, the female hormone that has been linked with tumour promotion. The relationship between estrogen and breast cancer, admittedly, is not a simply one. Laboratory studies have shown that estrogen, like many chemicals in the body, undergoes a variety of reactions after it is produced. Its metabolism, as these reactions are collectively called, can take two alternative routes. One produces 16-hydroxtyestrone, which seems to be the culprit in terms of stimulating the irregular multiplication of breast tissue cells. Alternatively, estrogen can be converted in into 2-hydroxyestrone, a compound that is relatively inert. Both of these conversions are governed by specific enzymes, levels of which can be affected by various factors. This is where indole-3-carbinol comes in. It stimulates the protective enzymes that take estrogen down the safe path, meaning that there will be less exposure of breast tissue to nasty 16-hydroxyestrone molecules.
That's pretty interesting stuff, but it's also pretty abstract for most of us. Probably not enough to persuade people to rush into the kitchen and start boiling cabbage. But wait. Mice develop fewer mammary tumours when exposed to indole-3-carbinol. Rats exhibit less endometrial cancer. But things get even more interesting when we discover that researchers have actually fed 400 milligram capsules of indole-3-carbinol to women on a daily basis (roughly equivalent to the amount in half a head of cabbage) and determined that it really did affect the way that estrogen was metabolized. Within two weeks the levels of 2-hydroxyestrone, the good stuff as it were, went way up. In fact, the levels rivaled those found in marathon runners, who are known to have a lower incidence of breast cancer.
So that's what happened to the pill poppers. But what about eating cabbage itself? Thanks to some Israeli research, we have an answer to that question as well. Eighty women on a kibbutz agreed to eat a diet high in cruciferous vegetables and submit their urine for analysis. The ratio of 2-hydroxyestrone to 16-hydroxyestrone in the urine increased, suggesting protection against breast cancer. It would be interesting to follow these women for a number of years and determine whether or not the breast cancer rate is actually lowered. There is a good chance that will happen, at least if we judge by some interesting epidemiological evidence from Germany and Poland.
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Excerpted from An Apple a Day: The Myths, Misconceptions and Outright Exaggerations about Diet, Nutrition and the Foods We Eat. Published by HarperCollins Publishers Ltd. Copyright 2007 by Dr. Joe Schwarcz. All rights reserved. Reprinted by permission of HarperCollins Publishers Ltd. A change of diet
Breast cancer rates in former East Germany were significantly lower than in West Germany, but after unification the disease pattern has become more equal. While obviously there were many difference in lifestyles between the two countries, it seems noteworthy that cabbage consumption was much higher in East Germany. This becomes even more meaningful in light of recent research carried out at the University of Illinois that examined why Polish women who have moved to the United States have a higher breast cancer rate than women in Poland. Cabbage is a staple in the Polish diet, but is less popular among Polish Americans. Was this a factor, the researchers wondered? So they stimulated test tube colonies of human breast cancer cells with estrogen and added cabbage extract. The cabbage-treated cells grew more slowly. And it was not a question of using unrealistic amounts of cabbage extract; doses were those achievable by eating normal amounts of the vegetable. Furthermore, the experiments suggested that the effect was due not only to the indole-3-carbinol. Other antiestrogenic compounds also seemed to be present in the cabbage juice.
You may now be ready to head towards the kitchen. Especially when you learn that cabbage is also high in vitamin K, which is receiving attention for its role in strengthening bones. The Nurses' Health Study found that those who consumed moderate to high amounts of vitamin K from vegetable sources had a 30 per cent lower risk of hip fractures. Still need more convincing? Consider the fact that epidemiological studies have shown that there is a lower risk of colon cancer among people who claim to eat cabbage regularly.
There is a trick to cooking cabbage. Do not boil it in water! That's how you release the smelly sulphur compounds. The general rule with cabbage is that the more you cook it, the worse the smell. So just stir-fry the shredded cabbage in a little olive oil until in turns brown, and then cook it in its own steam for a few minutes. Add a little salt, pepper and a touch of sugar. Then dump it on some freshly boiled thin noodles. You couldn't ask for anything better. Try it. It will taste a lot better that steamed Finnish newsprint.
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Excerpted from An Apple a Day: The Myths, Misconceptions and Outright Exaggerations about Diet, Nutrition and the Foods We Eat. Published by HarperCollins Publishers Ltd. Copyright 2007 by Dr. Joe Schwarcz. All rights reserved. Reprinted by permission of HarperCollins Publishers Ltd.