Does Soy Do A Body Good?

By Carolyn Suerth Hudson, RDN, LD
August 24, 2021

soy.jpgHave you ever wondered whether 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 bad 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 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 is believed that soy could reduce hot flashes, but in NIH’s National Library of Medicine a systematic review of 62 studies published in 2016 said there may be modest reductions, but further rigorous studies were needed to determine whether plant-based therapies, including soy isoflavones, were helpful for menopausal health.
  • 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. Two recent studies in 2021 showed conflicting results: one team in Columbia did not find a significant impact on puberty onset, while another team in Brazil DID find an association between soy consumption and early puberty, with those being breastfed to have a possible protective factor. Studies also show that using soy formula may stress the immune system later in life. Interestingly, 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-four 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 – according to the FDA. 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 phytoestrogens in soy: the phytoestrogens in unfermented soy can block the absorption of minerals like calcium, magnesium and zinc. The soy milk, 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).
  • 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 and it does not conclusively reduce hot flashes or protect you from reproductive cancers. 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 Soy Sparingly, If At All…

Traditionally soy was used as a condiment in its fermented forms—as soy sauce, 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.

What Can You Use Instead?

Look for animal sources like whey, beef, or egg which provide the most usable forms of protein for our bodies. With our Wellness Whey Protein powder (comes in chocolate, vanilla and natural flavor), one scoop contains18 grams of protein. If you’re looking for a dairy-free option, our Paleo Protein powder in chocolate or vanilla is a great tasting choice and gives you 21 grams of protein made from beef peptides with a full amino acid profile. For those who are looking for a plant-based protein powder, it’s better to go with a Pea Protein, which won’t give you the adverse reaction we shared above while giving you an excellent amino acid profile for energy and metabolism.

For drinking milk, if you and your family can handle dairy products, go for whole milk. Low-fat dairy products, such as skim milk, are deficient in vitamins A and D. Since vitamins A and D are necessary for growth, energy, and learning, food manufactures fortify low-fat dairy products with synthetic vitamin A and D. Synthetic vitamins are never as beneficial as what occurs naturally in food. When fat is removed from a product, usually carbohydrates or artificial ingredients are added for better flavor and mouth feel. Overall, it’s better to choose full fat options. (For more information on choosing quality dairy products, check out this article: Getting Smart about Dairy Products.)

What should you consider when substituting dairy for something else? Look at the label for added sugar, nutrient content, and any other additives. Ask yourself why you are using the product. Is it to replace milk in a recipe or add thickness in a smoothie? Once you know why you need it and what you’re using it for, then go from there to find the best substitute. You can always ask your nutritionist to help read the label and find a product that fits your needs and doesn’t sabotage your health.

For example, for those smoothies, filtered water with ¼ cup full fat coconut milk from the can is the best way to get in some healthy fat while getting the smoothy, creamy texture of a delicious shake. This How to Make the Perfect Smoothie article has a great infographic on all the other goodies you can include for a well-balanced smoothie.

Back To That Coffee Cup…

Healthy Coffee Creamer.jpgA good way to drink coffee would be to have it black, with heavy cream (if you can handle dairy), full-fat coconut milk, or unsweetened nut milk. For a healthy coffee creamer, check out this recipe with options for creaminess, sweetness, or additional flavor… depending on how you take your java.

We’ll cheers to you and your health!


For more information about soy, check out these resources:

About the author

Carolyn is a licensed dietitian at Nutritionl Weight & Wellness. Carolyn understands the impact nutrition has on health and well-being both professionally and personally. Working in a remote town in northern Canada, she saw the impact poor nutrition had on the health of people there. She then became committed to learning more and decided to pursue a degree in nutrition. Carolyn is a registered and licensed dietitian through the Minnesota Board of Nutrition and Dietetics. She received her BASc in Nutrition from Ryerson University in Toronto, Ontario, Canada and completed her internship at Toronto General Hospital. Carolyn is a past president of the Minnesota Academy of Nutrition and Dietetics and past director on the board of the Dietitians of Canada.

View all posts by Carolyn Suerth Hudson, RDN, LD

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