Pea protein powder is superior to soy protein in several ways, one of which is its hypoallergenic properties. While pea protein powder is completely hypoallergenic, soy protein is quite high in allergens, with studies finding up to 28 different proteins in soy which bind to IgE antibodies. IgE, for those who need a refresher course, is the immunoglobulin primarily responsible for allergic reactions within the body. Every body has different allergens, but when IgE antibodies are faced with a substance which is an allergen in a particular individual, it signals the body to release histamine, causing the traditional allergic reactions such as sneezing, rashes, digestive problems, lung irritation and increased mucus secretion. Consequently, the high number of soy proteins binding to IgE antibodies indicates a high potential allergic reaction in a large number of people. Importantly, the body can develop new allergies with continued exposure to a substance. Additional exposure past the time at which allergies develop will only increase the severity of symptoms. Thus, individuals regularly consuming soy protein run the very real risk of developing such allergic reactions.
There are other issues with soy protein which clearly make pea protein preferable. Unfermented soy contains enzyme inhibitors which inhibit proper protein digestion. Not only does this cause potentially embarrassing digestive problems, but it may also lead to the development of serious and deadly diseases including cancer. The enzyme inhibitors in soy are also growth inhibitors, making soy protein a poor main source of protein for children and adolescents, and a dubious one at best for athletes striving for muscle growth. Another drawback of unfermented soy is the presence of a high level of phytates which block mineral absorption in the intestines. Soy also contains phytoestrogens which, though beneficial in reasonable amounts, can have a negative impact on health when consumed in large quantities. A final questionable component of soy protein is goitrogens. These work within the body to suppress thyroid function, making soy a poor choice for individuals dealing with low thyroid function. The many ways in which soy protein may negatively impact health make it less than an ideal choice for regular consumption for a large proportion of the population.