The Soy in Pet Foods Myth

The soybean has a 5,000 year history in man and animals. It is in fact believed to be the oldest crop of civilization. It is the second largest U.S. crop, used in this country primarily for animal feed. It is a rich source of protein, oils and carbohydrates - in the bean's whole state.

In spite of its remarkable nutritional characteristics, soy has received much bad press in the pet food industry, and some producers even advertise "no soy" formulas as a reason to purchase their product. There is concern regarding allergic tendencies, production of excess gas perhaps predisposing to gastric distention/volvulus in the dog (un-proven1,2,3 ), and poor digestion. There is much current debate regarding this topic. Our research indicates that all of the potentially detrimental effects are a result of: 1. Using inferior soy by-products (only fractions of the actual soybean), and 2. Improper processing.

The prejudice against soy is so strong in some minds that the mind set alone creates "problems" in pets. For example, in controlled studies, pet foods containing soy placed in bags claiming "no soy" have been used for up to a year by pet owners with raves of satisfaction. However, as soon as the label on the bag was changed to reflect the actual soy contents (only the label was changed while the actual contents remained completely unchanged), many owners began complaining bitterly about the "change," claiming a whole host of ailments due to soy including: loose stools, gas, vomiting, hives, loss of appetite, skin problems, etc. The human mind's desire to view things in black and white, right or wrong, good or bad, makes it easy for advertisers to build a following behind simple but naive concepts such as "all meat" or "no soy." It is just too much work to be open-minded and fully informed, and advertisers work this to their advantage.

Raw soy has some built-in, anti-destruct mechanisms that interfere with digestive actions in monogastric animals. These include a variety of enzyme inhibitors including trypsin, chymotrypsin, and lipase. All of these must be neutralized, otherwise, when eaten, much of the soy simply bypasses enzymatic digestion in the upper GI tract, then passes into the lower bowel only to ferment, produce gas and other noxious products. Fat splitting and fat oxidizing enzymes must be neutralized also, and various allergenic factors, including hemagglutinin, must be inactivated by processing.

Heat will destroy all of these antinutritional agents, but so too does heat degrade the biological value of the nutrients. Wysong extrudes the whole bean using pressure and friction, so the bean is cooked for only 25 seconds. By so doing, the secondary protein bonds that impart the specific catalytic activity to antinutritional enzymes are broken, as are the allergic nature of proteins, but the primary peptide bonds are left intact, thus retaining full protein nutrient value.

Furthermore, the process ruptures the oil cells releasing linoleic acid, lecithin, natural tocopherol (e.g. vitamin E) antioxidants, amino acids (aromatic amines and sulf-hydryl compounds), and isoflavone glycosides and their derivatives.4 These compounds and oils then permeate the nugget to increase digestibility, protect against oxidation and increase palatability.

Soy starch cells are also ruptured and the contained starch is gelatinized, opening up the carbohydrate chain to increase water solubility and susceptibility to enzymatic digestion. Additionally, the soy vitamins are largely retained since the process does not use excess heat and is accomplished in an oxygen-free atmosphere.

Feeding products with Wysong whole soy as a special nutritional ingredient has created excellent results in thousands of animals through generations for over 10 years. Results achieved with Wysong foods - healthier skin and coat, increased vitality and disease resistance - are believed to be in part due to the special Wysong whole soy.

Special nutritional and health advantages of Wysong whole soy include:

  1. A complete complement of amino acids - balanced protein.
  2. Naturally complexed vitamins and chelated minerals.
  3. Essential naturally stabilized fatty acids including omega-3, 6 and 9 classes.
  4. Phytoestrogens decrease the carcinogenic (breast cancer for example) effect of increased exposure to environmental estrogens (See Wysong Health Letter-Vol. 8, No. 3)
  5. The lecithin (phosphatidyl choline) in whole soy increases the leukocyte (white blood cells) immune response, phagocytosis and killing of foreign germ cells.5
  6. The Bowman-Birk (Chymotrypsin) Inhibitor in whole soy has been shown to have anticarcinogenic (anti-cancer) activity.6
  7. Whole soy is especially concentrated in isoflavones and phytosterols, both of which have anti-cancer effects.7
  8. Genistein, an isoflavone in whole soy, can block new blood vessel formation critical for cancer growth.8
  9. Whole soy polysaccharides (fiber) improves the postprandial (after a meal) return to normal of blood glucose, thus improving the condition of the obese and diabetics.9
  10. The protein in whole soy is an effective treatment for hypercholesterolemia (high blood cholesterol).10
In contrast to Wysong whole soy, soy by-products normally used in pet foods - such as soybean meal, soy mill run, soy grits, etc.:

  1. Are what is left over after the rich oils have been mechanically or solvent extracted and sold elsewhere.
  2. Contain trace oils that turn rancid easily and create off-flavors.
  3. Are a product of high heat processing which destroys much of the biological value of the proteins and creates toxic end products. (Note: since protein level on a label is actually a measure of nitrogen, this destruction of biological value is hidden from the consumer.)
  4. Contain varying amounts of anti-nutritional factors that indeed may make a food product less than fully desirable. These include factors which can inhibit growth; depress metabolizable energy and fat absorption; reduce protein digestibility; cause pancreatic hypertrophy; stimulate hyper - and hyposecretion of pancreatic enzymes; agglutinate red blood cells; reduce availability of amino acids, vitamins and minerals, and gastrogenic activity; increase flatus through high levels of oligosaccharides such as raffinose and stachyose; increase lipoxidase oxidation of fat creating off-flavors due to generation of hexanal, hexanol and ethylvinylketone, and other off-flavor compounds such as aldehydes, ketones, alcohols, fatty acids, phenolic acids, amines and aliphatic esters.11,12
There is indeed a difference between Wysong whole soy and soy fractions. For example. The University of California at Berkeley, in addressing the benefits of soy, said this under the heading "All Soy is Not Created Equal:" "There's no standardized form of products are highly processed...after it is turned into flour, soy may not be that unique."13

Many producers add soy by-products as an inexpensive source of protein as an alternative to meat - a concession to price. On the other hand, Wysong specially processed whole soybean is specifically used because of its health and nutritional attributes. Its cost is greater than meat.

The best food for pet carnivores is their natural prey (impossible for companion animals). Second best is fresh food feeding (Very difficult to do; but refer to Wysong Fresh and Whole brochure, and audio cassettes: LifeSource and How To Think About Pet Foods.) Next best (and most practical) is the use of an optimally designed processed food (Wysong), in combination with fresh foods (better) and Wysong supplements. If processed foods are used, Wysong whole extruded soy proves to be an excellent ingredient to be desired, not avoided.

  1. "Canine and Feline Gastroenterology" ed. Jones and Liska, 1986:126
  2. Burrows, C.F., "Acute Gastric Dilation, New Methods," 1983, 5: 10-11
  3. Amer. Jour. Vet. Res., 1985, 46, 12: 2609-
  4. Hayes, R.E.,, "Antioxidant Activity of Soybean Flour and Derivatives," J. Food Sci., 42, No. 6, 1977: 1527.
  5. American Journal of Clinical Nutrition, September 1992;56: 599-603
  6. Nutrition and Cancer, 1993; 19: 281-302
  7. American Journal of Clinical Nutrition, September 1994: 333-
  8. University of California at Berkeley Wellness Letter, October 1993: 1
  9. American Journal of Clinical Nutrition, March 1987: 596-
  10. American Journal of Clinical Nutrition, May 1991: 1191
  11. Rackis, J.J., "Biological and Physiological Factors in Soybeans," J. Am. Oil Chem. Soc, 51. 1974: 161A.
  12. Harper, J.M., "Extrusion of Food II", CRC Press, Boca Raton, FL 1981: 113-
  13. University of California at Berkeley Wellness Letter, October 1993: 2
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