You asked why not soy steve. Here is a little background. References on soy below.
Soy GRAS Status
Lurking in the background of industry hype for soy is the nagging question of whether it's even legal to add soy protein isolate to food. All food additives not in common use prior to 1958, including casein protein from milk, must have GRAS (Generally Recognized As Safe) status. In 1972, the Nixon administration directed a re-examination of substances believed to be GRAS, in the light of any scientific information then available.
This re-examination included casein protein that became codified as GRAS in 1978. In 1974, the FDA obtained a literature review of soy protein because, as soy protein had not been used in food until 1959 and was not even in common use in the early 1970s, it was not eligible to have its GRAS status grandfathered under the provisions of the Food, Drug and Cosmetic Act.71
The scientific literature up to 1974 recognized many antinutrients in factory-made soy protein, including trypsin inhibitors, phytic acid and genistein. But the FDA literature review dismissed discussion of adverse impacts, with the statement that it was important for "adequate processing" to remove them.
Genistein could be removed with an alcohol wash, but it was an expensive procedure that processors avoided. Later studies determined that trypsin inhibitor content could be removed only with long periods of heat and pressure, but the FDA has imposed no requirements for manufacturers to do so.
The FDA was more concerned with toxins formed during processing, specifically nitrites and lysinoalanine.72 Even at low levels of consumption - averaging one-third of a gram per day at the time - the presence of these carcinogens was considered too great a threat to public health to allow GRAS status.
Soy protein did have approval for use as a binder in cardboard boxes, and this approval was allowed to continue, as researchers considered that migration of nitrites from the box into the food contents would be too small to constitute a cancer risk. FDA officials called for safety specifications and monitoring procedures before granting of GRAS status for food.
These were never performed. To this day, use of soy protein is codified as GRAS only for this limited industrial use as a cardboard binder. This means that soy protein must be subject to premarket approval procedures each time manufacturers intend to use it as a food or add it to a food.
Soy protein was introduced into infant formula in the early 1960s. It was a new product with no history of any use at all. As soy protein did not have GRAS status, premarket approval was required. This was not and still has not been granted. The key ingredient of soy infant formula is not recognized as safe.
And here are a few references to peruse if you chose on why no soy.
Doerge, Daniel R., "Inactivation of Thyroid Peroxidase by Genistein and Daidzein in Vitro and in Vivo; Mechanism for Anti-Thyroid Activity of Soy", presented at the November 1999 Soy Symposium in Washington, DC, National Center for Toxicological Research, Jefferson, AR 72029, USA.
Doerge, Daniel R., "Inactivation of Thyroid Peroxidase by Genistein and Daidzein in Vitro and in Vivo; Mechanism for Anti-Thyroid Activity of Soy", presented at the November 1999 Soy Symposium in Washington, DC, National Center for Toxicological Research, Jefferson, AR 72029, USA.
Doerge, Daniel R., "Inactivation of Thyroid Peroxidase by Genistein and Daidzein in Vitro and in Vivo; Mechanism for Anti-Thyroid Activity of Soy", presented at the November 1999 Soy Symposium in Washington, DC, National Center for Toxicological Research, Jefferson, AR 72029, USA.
Messina, Mark J. et al., "Soy Intake and Cancer Risk: A Review of the In Vitro and In Vivo Data", Nutrition and Cancer (1994) 21(2):113-131.
Harras, Angela (ed.), Cancer Rates and Risks, National Institutes of Health, National Cancer Institute, 1996, 4th edition. Rackis et al, "The USDA trypsin inhibitor study", ibid.
Anderson, James W. et al., "Meta-analysis of the Effects of Soy Protein Intake on Serum Lipids", New England Journal of Medicine (1995) 333
5):276-282.
Setchell, K.D.R. et al., "Dietary oestrogens - a cause of infertility and liver disease in captive cheetahs", Gastroenterology (1987) 93:225-233; Leopald, A.S., "Phytoestrogens: Adverse effects on reproduction in California Quail," Science (1976) 191:98-100; Drane, H.M. et al., "Oestrogenic activity of soya-bean products", Food, Cosmetics and Technology (1980) 18:425-427; Kimura, S. et al., "Development of malignant goiter by defatted soybean with iodine-free diet in rats", Gann. (1976) 67:763-765; Pelissero, C. et al., "Oestrogenic effect of dietary soybean meal on vitellogenesis in cultured Siberian Sturgeon Acipenser baeri", Gen. Comp. End. (1991) 83:447-457; Braden et al., "The oestrogenic activity and metabolism of certain isoflavones in sheep", Australian J. Agricultural Research (1967) 18:335-348.
I can provide another 100 or so study references if you want them, but I think these will keep you reading for quite some time.
