Does Soy Do A Body Good?

July 18, 2016

By Kate Crosby, BS, CNP

Have you ever wondered whether the current craze for soy is healthy? Once a client declared, as she raised her ubiquitous white and green paper cup, "This is decaf coffee with soy milk. I just wanted you to know." She was assuming I thought that was a good way to drink coffee. And yes, it was great that she left behind the flavored syrups with high fructose corn syrup and the fake creamers with trans-fats, but what about that soy milk?

Let's take a look at soy. Originally, soy was used in Asia as a cover crop to enrich soil. It was much later that Asians used it to season and enrich their meals. In the West, soy was used first by industries to make paper coatings, glues and even as fire-fighting foam. Around the 1950s, food companies started producing soy isolate and soy lecithin. Currently, you can find soy in many foods including soups, imitation meats, non-dairy creamers, infant formulas, cereals and protein powders. If you are allergic to soy, you know just how difficult it is to find foods that do not contain soy. It is everywhere.

Health claims about soy

Some sources have suggested that soy is a good source of protein that can reduce cholesterol and diminish hot flashes. Let's examine at these claims more closely.

• Soy has been advertised as an inexpensive protein alternative, especially for vegetarians, because it is high in protein and it contains all the amino acids, making it appear to be a complete protein. However, the body cannot use soy to make muscles, bones or hair as well as it can utilize meat, eggs or fish.
• In 1999, the FDA approved soy as a food to reduce cholesterol and heart disease; however, to get these results the FDA recommends eating a pound of tofu daily (a serving size is 3 ounces)! In 2005, the American Heart Association officially disagreed with that claim after reviewing many studies claiming soy's benefits. This panel also found that soy was not effective at reducing hot flashes or reducing cancers of the breast, uterus or prostate.
• It was believed that soy could reduce hot flashes, but Reuters (Reuters, May 17, 2010) reports that after an analysis of nineteen studies using soy to reduce hot flashes in post-menopausal women, the evidence is inconclusive.
• Soy is also used in formulas for infants who are sensitive to cow's milk and are not being breastfed. There are concerns that soy infant formula may be contributing to the early puberty in girls and the late puberty in some boys. Studies also show that using soy formula may stress the immune system later in life. In light of these findings, in 2005, Israel joined France, New Zealand, and Australia in recommending limited use of soy in young children and if possible, avoiding it all together.

Health concerns about soy

At Nutritional Weight & Wellness, we recommend that our clients are cautious in using soy for several reasons.

• Soy is difficult to digest, which can cause gas, bloating and general discomfort. Fermented forms of soy, such as miso, tempeh or soy sauce are more easily digested than non-fermented soy foods.
• Ninety-three percent of the soy in the U.S. has been genetically modified—a process whereby a crop is altered by a virus or bacteria with a desired trait, such as resistance to a weed killer. Genetically modified (GM) foods have only been used for the past decade so we do not know the long term effects of these foods on our health. One concern is an increase in allergies.
• Soy can interfere with thyroid function, which may affect your metabolism.
• Soy contains phytoestrogens. These are the chemicals that can mimic estrogen in your body. I mentioned the concerns about soy's effects on puberty and on the immune system that parents of newborns have. However, adults have other reasons to be wary of the phystoestrogens in soy:

• The phystoestrogens in unfermented soy can block the absorption of minerals like calcium, magnesium and zinc. That soy milk, those protein bars and protein powders that you may use to improve your health may in fact be preventing you from building strong bones (calcium), relaxing (magnesium) or preventing the flu (zinc).
• According to Cancer Research, phytoestrogens may be carcinogenic—raising questions about the safety of consuming soy.

• Soy decreases sperm counts and testosterone levels. In 2010, Dr. Chavarro, M.D. from Harvard University, reported in the Journal of Human Reproduction that there was a strong association between men's consumption of soy and decreased sperm counts. Others have noted that testosterone levels decrease with soy consumption.

Let's summarize these findings. Soy can interfere with thyroid function. It is difficult to digest and does not allow you to fully absorb minerals. Soy has an estrogenic effect—reducing fertility in men, it does not conclusively reduce hot flashes or protect you from reproductive cancers. And as an infant formula, soy may cause early puberty in girls or late puberty in boys or stress our immune system. It really is not a complete protein that works in your body. So, soy milk in your coffee may be doing nothing beneficial for you and may have some serious unwanted effects.

Use it sparingly, if at all…

Traditionally soy was used as a condiment in its fermented forms—as soy sauce, or miso in soups or small amounts of tempeh with rice and vegetables. Asian cultures use soy sparingly and traditionally. Soy milk, soy powders or protein bars do not exist in their diet. Research reveals that soy's benefits are inconclusive and may in fact prove to be harmful. If you like soy, use it sparingly, as a condiment or according to the recommendations of your nutritionist.

For more information about soy, listen to our June 25, 2011 radio show: The Dark Side of Soy.