You may eat soy in your stir fry or use it as a substitute in your morning latte. You can eat soybeans in many forms, including tofu, the beans themselves (also called edamame), soy milk, miso, and soy powder.
Soy may not be immediately harmful, but it can undermine your health significantly. Soy can disrupt thyroid and endocrine (hormonal) function. It can contribute to fatigue, constipation, menstrual irregularities, and perimenopausal or menopausal issues.
Soy can also interfere with leptin sensitivity, leading to metabolic syndrome. Soy can also interfere with your utilization of certain minerals like iron, zinc, calcium and magnesium. Soy can trigger inflammation in many people. Thus, many people have a food sensitivity to soy.
So what about soy and breast cancer?
Soy contains a lot of isoflavones, which are weak estrogen-like compounds. This is a worrisome for many breast cancer patients who have hormone positive cancers as the theory is that soy can promote and increase progression.
Soy is not new. It has been used in Eastern Asian diets for generations. Is that why hormone sensitive cancers are seen less often in Asian women? Soy is usually consumed in the fermented form like tempeh, miso, natto, and tamari. Fermented soy is very different than the usual soy and the fermentation process actually increases its health benefits. Also, there are other contributing factors in a typical Asian woman's diet like more vegetables and consuming less alcohol.
The biggest problem I have with soy is that it is one of the biggest GMO crops in the United States. GMO crops disrupt your microbiome - which is the center of your immune system - your defense against cancer. Reports state any where from 94-98% of the soy produced in the US is genetically modified. Scary!
My advice on soy:
Eat fermented forms of soy like tempeh, miso, natto, and tamari.
Eat soy in moderation - this is not a pass to suddenly start eating soy, especially if you have not been eating it your entire life.
Eat only organic forms of soy.
Do not take supplements with soy.
Always eat a variety of veggies - eat the rainbow (not skittles...)!