Soy can have both very positive and negative effects on our health. The positive or negative effects are linked to the type and amount of soy products consumed, in addition to the gender, age, and overall health of an individual. As a plant-based eater, I find soy to be a common ingredient in most foods labelled as vegetarian or vegan. Without a properly balanced whole-foods, plant-based diet and adequate supplementation (in some cases), plant-based eaters risk mineral deficiencies when they substitute tofu (bean curd) for meat and dairy.
Types of Soy Foods
Unfermented: Soybeans (edamame), Soy Nuts, Soy Milk, Tofu, Dry Soybeans, Soy Flour
Fermented: Miso, Soy Sauce, Tempeh, Natto, Fermented Tofu (not all Tofu is fermented), Fermented Soy Milk (not all Soy Milk is fermented)
Three Positive Effects of Soy
1. It is a great source of unsaturated fat (85% unsaturated); contains essential fatty acids, it lowers cholesterol, and protects against certain types of cancer (found to be positively effective on bladder cancer).
2. It is high in lecithin - improves cholesterol levels, liver and gall bladder function, and neurological disorders.
3. It is high in fiber – 94% insoluble fiber helps with constipation, diarrhea, high cholesterol, and diabetes.
Note: There are also positive characteristics of soy: It is an excellent protein source and a good source of Vitamins B1 (thiamine), B2 (riboflavin), B6 (pyridoxine), E, Folic Acid, Iron, Calcium, and Phosphorous.
Five Negative Effects of Soy
1. It contains Isoflavone – Genistein which can stimulate anxiety/panic; not to be consumed with Monoamine Oxidase Inhibitors or antidepressant drugs (when there is a presence of mental illness).
2. It inhibits thyroid function in people, who already have a thyroid condition.
3. It can cause gastric distress, amino-acid deficiency, and pancreatic cancer (when there is a presence of compromised pancreatic function).
4. Isoflavones decrease the insulin-like growth factor which helps balance insulin.
5. Highly allergenic – soy is one of the top seven most allergenic foods.
Bottom Line: There are positive and negative effects of consuming soy. Overall, it is a good source of protein, fiber, lecithin, and unsaturated fat, but its negative effects could outweigh the positive outcomes for those with certain medical conditions.
Source: Dominique Hodgin, MA, NE, Executive Director of Education of Dr. Sears L.E.A.N. Programs: Dr. Sears Wellness Institute