Q. What are your views about consumption of soy products? Many people claim that eating soy products is associated with heart disease, cancer, Alzheimer's and other problems.

A. Soy has been the major source of vegetable protein in Asia for centuries and the Japanese diet includes multiple servings of soy products every day. We based our dietary recommendations in part on the Japanese diet in large part because the Japanese live longer than any nation on earth. This seems an unlikely result if they have been eating a toxic food every day for centuries.

Every food is toxic to some degree, and this toxicity is often magnified when animals are fed large amounts of a specific food and then conclusions are drawn about what would happen if people eat this food. For example, celery can raise blood pressure, broccoli contains a naturally occurring pesticide shown to cause mutations, while mushrooms and peanuts contain known carcinogens. But, few people would suggest that these foods never be eaten. Moderation is the key.

The same applies to soy. Laboratory studies have shown that there can be problems when soy is consumed in large amounts by animals. We do not advocate large amounts of soy consumption. Moderate amounts have been shown to be associated with health benefits.

The following is additional information on this question from our web site: http://fantastic-voyage.net/ReaderQandA.htm:

A number of books, articles and newsletters have taken the position that soy is far from the health food that many vegetarians and others have claimed. Rather, their feeling is that soy is harmful and should be completely avoided. Yet, in the course of our research, we have concluded that consumption of moderate amounts of soy products can (and should) play an important role in our longevity program.

The Ray & Terry Longevity Program advocates a reduction in carbohydrate consumption for most people in order to help control weight and appetite, as well as to help control blood cholesterol, sugar and insulin levels. As carbohydrates decrease, then, of necessity, the percentage of calories derived from fat and protein must increase. While there are good fats such as in the form of olive oil, avocados, fish and nuts, most medical authorities advocate that fat consumption be controlled to avoid excess weight and other potential health problems. Therefore, protein consumption needs to increase somewhat.

Protein can be obtained from animal or plant sources. While there are beneficial aspects to consuming healthful animal protein such as fish, low fat dairy products and skinless poultry, there are also problems associated with each of these foods. For example, almost all fish are now contaminated to some degree with mercury, and many people are allergic to dairy products or intolerant of the lactose in milk. Therefore, it is beneficial to obtain a significant part of our daily protein from vegetable sources.

Soy has been the major source of vegetable protein in Asia for centuries and the Japanese diet includes multiple servings of soy products every day. We based our dietary recommendations in part on the Japanese diet in large part because the Japanese live longer than any nation on earth. This seems an unlikely result if they have been eating a toxic food every day for centuries.

The bottom line is that every food is toxic to some degree, and this toxicity is often magnified when animals are fed large amounts of a specific food and then conclusions are drawn about what would happen if people eat this food. For example, celery can raise blood pressure, broccoli contains a naturally occurring pesticide shown to cause mutations, while mushrooms and peanuts contain known carcinogens. But, few people would suggest that these foods never be eaten. Moderation is the key.

The same applies to soy. Laboratory studies have shown that there can be problems when soy is consumed in large amounts by animals. We do not advocate large amounts of soy consumption; rather, we suggest daily consumption of smaller amounts that have been shown to be associated with health benefits.

For example, animal experiments have shown that soy protein consumption can lead to a 22% decrease in breast cancer, a 30% decrease in colon cancer and a 34% decrease in prostate cancer. (Badger TM, Ronis MJ et al. Soy protein isolate and protection against cancer. J Am Coll Nutr. 2005 Apr;24(2):146S-149S.)

Soy has been proven to protect against heart disease and the FDA has allowed the following health claim about soy: "25 grams/day of soy protein, as part of a diet low in saturated fat and cholesterol, may reduce the risk of heart disease." The American Heart Association has officially recommended consumption of 25 grams or more of soy protein daily.

Much has been made over the association between soy and Alzheimer's in Japanese men in Hawaii reported as part of the Honolulu Heart Program. But, according to author John Robbins, there is a lower incidence of Alzheimer's in Japanese men living in Japan where more soy is eaten than in Hawaii. He cites a Hawaiian physician, Dr. Bill Harris, who found that soy products in Hawaii have a higher content of aluminum than soy products made elsewhere. He suggests that it is the increased amount of aluminum in Hawaiian soy products that led to the higher incidence of Alzheimer's in this population.

It remains our contention that moderate soy consumption can play an important role in anyone's longevity program.