Should I Eat Soy? What the Research Says
April 21, 2020
For many years, experts have debated the safety of soy consumption. The evidence has in some ways been inconsistent and contradictory, which only fuels the fire. However, recent data suggests this nutrient-dense source of protein has either a beneficial or neutral effect on health. When eaten as an alternative to red and processed meat, soy can safely be consumed by most people several times a week.
Soy and Isoflavones
Part of the controversy stems from the fact that soy naturally contains a high concentration of compounds called “isoflavones,” a type of phytoestrogen that functions similarly to the female reproductive hormone estrogen. While these phytoestrogens are much weaker than the human hormone and sometimes actually act as an antagonist to the hormone’s function, some research indicates this can impact things like thyroid function, and increase risk of developing certain cancers.
However, to say that soy in general will impact everyone in this way is not the most accurate statement. There are several factors at play here, some of which include the variety of research study designs; the ethnicity and hormone levels of the subjects being studied; and the type of soy being consumed. Because of this, it is challenging to make broad statements that accurately portray soy’s influence on physiological function.
What’s Good About Soy
While the estrogenic effects of soy are inconclusive and individual, there are several important factors that we can be confident about.
- Soy is high in protein, and because it contains all nine essential amino acids that cannot be produced by the body, it is one of the rare plant foods that falls under the category of a complete protein.
- Including soy in the diet is important for maintaining adequate protein intake for people who don’t consume animal sources of protein on a regular basis. It is also a good source of important omega-3 and omega-6 fatty acids and is lower in carbohydrates, which can be advantageous in controlling blood sugar, especially for those with diabetes.
- Aside from its desirable macronutrient profile, soy also contains important vitamins and minerals that contribute both to overall health and physical performance. These include calcium, magnesium, potassium, iron, and B vitamins, all of which contribute to bone strength, muscle contraction, oxygen transport, metabolism, and cell turnover.
- Fiber is also another component of soy that is important for regulating GI function and contributing to satiety. Soy in its most natural form will have the highest nutrient value, and thus should be prioritized. This includes soybeans (also called edamame) and any other items made from soybeans, including soymilk, tofu, tempeh, miso, and plant-based meat and dairy substitutes like soy meats and soy cheeses.
- Choosing minimally-processed plant-based foods more frequently than animal sources, reduces the carbon footprint for the environment and possibly discourages the potential for unethical treatment of animals that are being used for food.
Who Should Avoid Soy?
Soy should be avoided by people with a soy allergy or who suffer from irritable bowel syndrome. However, for most people, soy is a valuable food source to incorporate in the diet.
McKenna Welshans, MBA, RD, LDN, ACSM-EP
McKenna Welshans, MBA, RD, LDN, ACSM-EP is a sports nutritionist with LG Health Physicians Sports Medicine. She completed her undergraduate and graduate degrees and a dietetic internship at Messiah College, double majoring in nutrition and exercise science. She ran collegiate track before transitioning into ultra-endurance triathlon competitions. She is passionate about personalized nutrition for both performance maximization and health.