What's New About Soya?

By Milton G. Crane, M.D.
NEWSTART Research Director

Recently I took my favorite dietitian to attend a conference^1,2 on, what I thought was the soybean. It turned out to be a conference on soya. What is the difference? Soya includes the entire plant, not just the bean. This very interesting meeting was sponsored by the soybean growers from Nebraska and Indiana and the United Soybean Board. It was organized by one of their consultants, Mark Messina, Ph.D. of Maryland. In my opinion, this meeting was of great importance to all those interested in vegetarians foods, especially Seventh-day Adventists, since they have been in the forefront of the manufacture and the use of foods made of soybean products.

We learned much more than just the benefits of certain nutrients of the soybean in the prevention of atherosclerosis and cancer. The emphasis was on how to increase the market for soya, bean and all. Soybean growers are not content just knowing this incredible legume is a rich source of a high quality protein and essential oils for food. Even though it can be turned into soy diesel to fuel trucks and busses, chemicals to build marble-like countertops and coffee tables, fabricate plastics, soy fabrics, plastic utensils, paint, and adhesives, the uses must be increased. Growers illustrated their point by printing their brochures and announcements on recycled paper with soy ink.

As health workers, we were interested in the soybean for more than its use in helping make the antibiotic, streptomycin. We knew that it had long been a better source of nutrients than the milk and flesh of animals. We had heard that a new chemical to help prevent cancer, called genistein, could be found in the soybean as well as in shark cartilage. Let us briefly examine the highlights of the 38-plus lectures given by prominent investigators in the field and the 29 exhibits in the Poster section.

Soybean Processing and Products: Five excellent presentations were given on the processing of the soybean and its products. These talks were about the soybean as food. Farmers of America produce half of the world's supply. In 1992 the total U.S. acreage in soybeans would cover the state of Arizona. The one-third of the bean crop that was exported that year directly reduced the U.S. trade deficit by almost 4.5 billion dollars.

About sixty percent of the beans are processed for soy oil. They are dehulled and flaked, and the oil is extracted by hexane. This crude oil is then degummed, refined, bleached, and deodorized to make soy oil isolate. The oils may be oxidized and natural emulsifiers, such as the lecithins, are removed.

Soybean meal residue is the leading source of protein for meat and poultry animals. From this soybean meal, soy grits, soy flour, textured flour, soy protein concentrate, and soy protein isolate are made. Soy protein concentrate and soy protein isolate are of particular interest because these two have gone through extraction to remove the flatulence-causing, sugars. Unfortunately, the extraction process also removes about 90 percent of the fiber and certain other very important chemicals. A better word might be subtraction process. It is in this step also where solvents and heat may alter, not only the remaining oils, but also the proteins. A descriptive word for this step would be modification process.

Of all the plant oils, the soybean supplies 75 percent of the 20 billion pounds used per year for food. Last year the average American ingested over 40 pounds of soy oil as salad oil, margarine, or shortening. Approximately 17 percent is eaten as margarine and over half of the fat has been changed from the cis-form to trans-fatty isomer.3 Eating that much fat in the free state contributes too much toward the development of atherosclerosis, obesity, diabetes, and other chronic degenerative diseases. No average American needs the detrimental effects of this 3.5 pounds per year of trans fats to be added to that of the free fats.⁴

Soybeans, Cholesterol Metabolism, and Atherosclerosis: The next fifteen papers dealt with the beneficial effects of the soybean to lower cholesterol and prevent atherosclerosis. Kritchevsky and then Caroll1 reviewed the evidence that soy and other plant proteins lowered cholesterol, whereas animal protein such as casein raised serum cholesterol. They showed in animals that this is due to the high lysine/arginine ratio in milk protein.

In the poster session we⁵ presented our preliminary evidence that only 8 percent of 38 persons on a total vegetarian diet without refined foods for a year or more had a serum lipoprotein (a) [Lp(a)] which is above 15 mg percent. Their Lp(a) averaged 6.8 mg percent. By comparison, 43 percent of 30 lacto-ovo-vegetarians (LOV) and 38 percent of 95 omnivores (OMNI) had values over 15 mg percent and their values averaged 21 to 22 mg percent. We also found that after two weeks on the NEWSTART Program, the Lp(a) had decreased by an overall average of l4 percent in the OMNI and LOV persons. On the other hand, the Lp(a) values of eighteen persons who were habitually using a powdered soy milk which contained soy oil and soy protein isolate, averaged 21 mg percent and over half of them had Lp(a) values over 15 mg percent. This is important because Lp(a) is an independent risk chemical. People with elevated values, at least those over 30 mg percent, have a higher risk of getting atherosclerosis.^6,7

Anthony¹ and Associates reported a study of 13 female monkeys, half on a diet which included soy protein fortified with phytoestrogens, the same chemicals that prevent cancer, had an Lp(a) which was 25 percent lower than the other half who were using unfortified soy protein isolate.

These preliminary data indicate that something has happened to the soy protein and/or the soy oil so that the ordinary low-density lipoprotein complex has an antigenic protein in its structure, which makes it detrimental to the prevention of atherosclerosis.

Soybeans and cancer: The final eighteen papers dealt with the relationship of soy foods and the prevention of cancer. The gist of the presentations was this. Cohort and case-control studies indicate that the consumption of raw vegetables and fruit like green leafy vegetables, carrots, broccoli, cabbage, lettuce, and citrus fruit, slows or prevents the appearance of cancer.

The soybean has four classes of chemicals that prevent cancer: isoflavones, protease inhibitors, inositol phosphates, and saponins. Space does not allow us to discuss these, but they are all important. Soybeans appear to be the major source of isoflavones, protease inhibitors, and saponins in the human diet. Much of the conference focused on isoflavones. These are plant nonsteroidal estrogens like genistein and diaidzein. Of particular importance was the emphasis by Barnes and associates that up to 90 percent of these isoflavones may be lacking in the usual soy protein isolate.⁸

Here we need a word of caution, lest someone shifts to an all raw vegetable or raw cereal diet. These foods must be prepared right. It has been known for some time that soybeans need to be cooked to inactivate an enzyme (a protease inhibitor), that causes enlargement, hyperplasia, and even cancer of the pancreas in animals. On the other hand, processing the soybeans to soy oil isolate and soy protein isolate is not the best. Messina⁷ stated that up to 90 percent of the soy fiber and isoflavones are missing from the soy protein isolates. We plead with the food processors to correct their methods so that we can have the benefit of the whole soybean.

The same thing applies to all plant foods. Potter summed it up with these words, "Reduction of consumption of plant foods means reduced intake of a wide variety of substances that lower cancer risk. Vegetables and fruit contain the anti-carcinogenic cocktail to which we are adapted. We abandon it at our peril."¹ To that statement we would add that we were designed to be vegetarians, and the natural produce of the garden was designed for our health and enjoyment by our Creator.

References
¹ Abstracts of the First International Symposium on the Role of Soy in Preventing and Treating Chronic Disease. Mark Messina, Ph.D, Program Director, Mesa, Arizona, February 20-23, 1994.
² '93 Soya Bluebook. Published by Soyateck, Inc. Bar Harbor, ME 04609.
³ Carpenter DL. J Amer Chem Soc 1976, 53:713.
⁴ Heckers H, et al. Atherosclerosis, 1977, 28:389.
⁵ Blankenship J, Crane M, et al. (See, Abstracts in Reference #1).
⁶ Simon DL. Loscalzo J. Choices in Cardiology. 1993; 6:7-9.
⁷ Rader DJ, Brewer HBJr. JAMA. 1992, 267:1109-1112.
⁸ Coward L, Bames NC, Stechell KDR, Bames S. J Agri. Food Chem. 1993, 41:1961.
⁹ Messina, M. Libertytown, MD. Personal Communication.

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