Eating Well Food News
Soy for Prostate Cancer Diet - Do Heart-Healthy Labels Benefit You Too?

June 20, 2000. Men dealing with prostate cancer as well as vegetarians, vegans and health enthusiasts may be interested in eating soy foods in place of meat, poultry, cow's milk, cheese and other animal-based foods.

As more Americans include soy milk and tofu in their diet, consumption of all types of soy foods is rising steadily, boosted by scientific studies showing health benefits from these products.

UK researchers say a vegan diet cuts the risk of prostate cancer. An earlier study of Seventh-Day Adventist men in California found that those who drank soymilk at least once a day had a 70% reduced risk of developing prostate cancer. Similar results show up for Japanese men living in Hawaii who ate tofu.

Soy benefits may apply to men already in treatment for prostate cancer. High concentrations of a soy-isoflavone, genistein, according to a Detroit team including Dr. Kenneth Pienta, block PSA expression in androgen-independent VeCaP cells. The researchers also showed that genistein inhibits cell proliferation independent of PSA signaling pathways. This, they say, supports "the role of genistein as a chemopreventive/ therapeutic agent for prostate cancer irrespective of androgen responsiveness."

Although they have not tested it yet on human patients, researchers do not rule out the usefulness of genistein supplements for advanced disease as well as for prevention and early stage disease.

The FDA discourages consumers generally from treating soy as a medicine or drug. They are quite concerned about sale and use of genistein pills. Genistein may cause, for example, growth of breast tissue in men. Plant-chemicals extracted from soy have strong effects on the hormonal systems of men and women. This is exactly why patients as well as medical researchers are interested in the impact of soy on prostate and breast cancer, which are fueled by hormones.

If you are a man dealing with prostate cancer, you will want to take genistein supplements yourself only on the advice of your medical team and at doses your doctor is prepared to recommend. Some effects of soy isoflavones might turn out to be negative. Evidence has even been found that a lifetime diet of soy ages the brain. Keep high-concentration supplements out of reach of young children and (just as obviously) don't push them onto women who might be pregnant.

As for foods, since October 1999 FDA allows U.S. food manufacturers to label products high in soy protein with the claim that these may help lower risk of heart disease. In order to qualify, a serving, or portion, of the product must meet the following Food and Drug Administration standards:

• 6.25 grams soy protein or more
• Low fat (less than 3 grams)
• Low saturated fat (less than 1 gram)
• Low cholesterol (less than 20 mg.)

The claim applies to products that a person can be expected to eat or drink in the amount of 25 grams per day.

Are these standards truly helpful? Or were they perhaps designed to favor manufactured, value-added soy protein powders and products over regular soy foods? Look at Naturade's Total Soy, "The Ultimate Meal Replacement." Three great flavors (Strawberry Creme, Bavarian Chocolate, French Vanilla). "Add milk and this all-natural, low-fat meal replacement transforms into a rich, frothy, delicious shake."

Add milk? Wait a second, those Adventist men who lowered their risk of prostate cancer didn't add milk to a powder. They drank soymilk. In doing so they got benefits from soy isoflavones while avoiding components of cows' milk, which may not be as healthy as most Americans assume.

Those Japanese gentlemen in Hawaii didn't add milk to Bavarian Chocolate and call that lunch. They ate tofu as part of their meals -- which, likely, included rice and a variety of vegetables. So along with the tofu the men got other healthy nutrients. If they also ate a bit of fish, typical Japanese fare, this added more prostate- and/or heart-healthy value to their meals (even though the FDA does not put a label on fish).

A healthy meal can be shared, it is much more sociable than a shake designed to replace a meal. Sociability relieves stress and is believed to contribute to longevity.

The FDA label for soy heart-healthy groceries came about by a petition filed in 1998 by the Dupont company Protein Technologies International. PTI specializes in turning soybeans into powder. FDA agrees that Dupont's research shows that regular soy protein consumption lowers cholesterol to varying degrees. FDA says that other studies "hint" that soy may have benefits for osteoporosis, prostate cancer, and colon cancer.

Dupont's soy powder product SUPRO set the FDA standard for heart-healthy soy labeling. An unfortunate effect of this is to make regular soy products look second-rate. For example, a serving of regular tofu such as Nasoya's Extra Firm has more protein than the FDA recommendation -- but it also has rather more fat. Nasoya's website displays a heart design, yet as far as we can see, unless Nasoya de-fats it, Extra Firm will not be allowed to carry an official FDA good for the heart label.

Consumers could pressure Nasoya and other tofu-makers to skim the fat -- and hope that this does not spoil the texture. Or choose Firm or Silken instead of Extra Firm, or switch brands, for example to Nori. But isn't this rather absurd? Good tofu can be bought out of a barrel in a corner grocery store, as long as the barrel water is clean. Why not just do more to persuade the American public how tofu makes a healthy ingredient in a meal?

Instead, just when North Americans become familiar with tofu and soymilk and start using them in daily meals, the FDA opts to support soy powder and nutritional soy bars tested on Romanian athletes.

Indiana Soybean Board now promotes super nutritional soy powders while almost apologizing for whole soy foods. "Foods made with the whole soybean may also qualify for the health claim if they contain no fat in addition to that present in the whole soybean. These would include soy foods such as: tofu, soymilk, soy-based burgers, tempeh, and soy nuts."

Bob Dylan sang in the 70s, "They don't even know how to feed themselves." Really, many still don't. The FDA is not helping by creating a situation in which a standard brand of tofu cannot be labeled as positive a good food compared to products enriched with high protein soy powder. Products such as a $1.29 peanut butter flavored bar "meal" that also includes fractionated palm kernel oil, cellulose, 160 mg of salt and 19 grams of sugar.

High-power soy candy bars bring back memories of diets in a can, which Americans went crazy for. They did not stop the epidemic in obesity. On the bright side, supermarket shelves are filling up with products such as soy luncheon meats, soy "cheese" slices, soy burgers with zero fat and quite reasonable taste except for too much salt. These are quick and handy.

We tried soy hot dogs the other day. I doubt they'd fool a three-year-old. Still, if you look about and use your judgment and your tastebuds, this is a pretty good era for soy as part of a healthy prostate and healthy heart diet. And therapeutic uses of soy may be on the way.

Int J Oncol 2000 Jun;16(6):1091-7 Inhibition of prostate specific antigen expression by genistein in prostate cancer cells. Davis JN, Muqim N, Bhuiyan M, Kucuk O, Pienta KJ, Sarkar FH Department of Cancer Biology, Karmanos Cancer Institute, Wayne State University, Detroit, MI 48201, USA

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