Another Cancer Study Suggests Importance of a Balanced Diet
by Tim Steury WSU News and Information, [email protected]
Contrary to rumor, rats are not humans. Still, certain laboratory-resolved relationships in rats are unsettling, to say the least. Give a rat a high fat diet, and tumors proliferate. "It's like fertilizer," says Assistant Professor of Zoology Paul Sylvester.
In humans, the relationship between dietary fat and cancer is not quite so clear cut. Still, the correlation is strong. Increased fat intake increases the risk of certain kinds of cancer. Colorectal cancer is a given. The breast cancer connection is more tenuous. Even though the cause of most breast cancers is unclear, the evidence places considerable blame on fat consumption.
There are, however, exceptions. The most notable is palm oil.
Sylvester gets his palm oil in big tins straight from the Palm Oil Research Institute of Malaysia. Raw palm oil does not appeal to the American palate. It is red. Its odor is less than appetizing. As a result, it is difficult to get in this country. Here it comes in a more presentable refined form--which is why the palm oil available in this country has very little anti-tumor activity.
Palm oil contains all the bad stuff that nutritionists rail against. It's very saturated. "You'd think it would be terrible for your health," says Sylvester. So what's it got that other fats don't?
Palm oil is loaded with antioxidants, particularly vitamin E. Antioxidants protect your body from highly reactive free radicals that damage cells. The results of oxidative damage to cells in the human body include heart attack, stroke, aging--and cancer.
But palm oil's vitamin E is not your average vitamin E. Actually vitamin E is simply a generic term. It comes in several forms, with varying properties and effects. The two classes of vitamin E are "tocopherol," which is the form available as "vitamin E" in supplement form, and "tocotrienol," which is what palm oil primarily contains.
Although tocopherol is an excellent antioxidant, it has little effect against breast cancer cultured in laboratory animals.
Tocotrienol is quite similar to tocopherol, except that it has an unsaturated tail in its chemical structure. The difference in its effect, however, is dramatic. Add tocotrienol to the diet and it inhibits tumors. It readily kills tumor cells grown in culture.
Sylvester and his colleagues conducted a study recently to compare normal cells with the various stages of tumor growth: preneoplastic, neoplastic, and malignant.
Preneoplastic cells look normal, though they're not. They have sustained genetic damage. They are also immortal.
Place preneoplastic cells in a culture dish and they will divide indefinitely. That's one of the characteristics of cancer. However, although they keep dividing, preneoplastic cells do not form tumors, not until they progress to the more advanced stages of neoplastic transformation. Then they can become malignant and even begin to metastasize to other tissues.
In his studies, Sylvester found that tocotrienol will inhibit, even kill, normal cells, but doing so requires very high doses. Curiously, the more cancerous the cell, the more susceptible it is to the cytotoxic effects of tocotrienol. Malignant and highly malignant cells are very sensitive to the compound.
Tocotrienol also behaves much differently than tocopherol. Tocopherol accumulates in specific organs, specifically the liver, kidney and prostate. Tocotrienol tends to accumulate in adipose tissues. The mammary glands are predominantly fat, so tocotrienol concentrates there.
Even though it is fat soluble like vitamin A, vitamin E is essentially nontoxic because its absorption and transport in the body is very limited. It will concentrate in the body only to a certain point, whereupon the excess is excreted.
It appears tocotrienol stored in the fatty tissue of the mammary gland is benign to the normal cells. But when cells turn bad, tocotrienol then acts to inhibit growth and kill cancer cells.
Epidemiological data seems to bear out the results of Sylvester's work. Although they eat high levels of palm oil, residents of the Asian Pacific Rim have very low incidence of breast cancer. Interestingly, even though palm oil is highly saturated, people in Malaysia and the Asian Pacific Rim in general do not suffer high rates of cardiovascular disease. The truth seems to be in the mix. Sylvester believes it's the high levels of vitamin E and other protective compounds and antioxidants in palm oil that protects them.
Sylvester recently presented his work at an invited colloquium at the National Institutes of Health on cancer prevention and control. Much interest has been shown in the relationship between diet and cancer--and in vitamin E as an antioxidant and chemopreventative agent. But Sylvester believes his data show that everyone has been focusing on the wrong form of vitamin E, the tocopherols, which show little effectiveness against breast cancer. Such a mis-focus is understandable, as tocotrienol is very difficult to obtain.
Sylvester's work seems to be a further step toward understanding the protective role of vitamins and other nutrients in the diet. This understanding is becoming more and more sophisticated. Different forms of vitamin E, as well as other vitamins and micronutrients, seem to migrate to different parts of the body where they play their protective roles.
No single nutrient is a single bullet. Protection depends on their cumulative effect. In other words, what this work further suggests is simply that eating a variety of fruits and vegetables is good for you.
Palm oil sold in the U.S. is refined to remove the somewhat objectionable color and odor. Unfortunately, the refining also removes its protective qualities. In spite of the dearth of raw palm oil in this part of the world, tocotrienol is available through some other foods, including rice bran oil and wheat bran oil, though not nearly in the concentration available in palm oil. So far, no one has been able to synthesize the compound.
Until this society becomes truly global in its tastes as well as its distribution, tocotrienol seems a good excuse to move to Malaysia.
The above story is based on materials provided by Washington State University. Note: Materials may be edited for content and length.
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