I took Soy Isoflavones when I was trying to conceive my third child. I took it for one cycle from cycle day 3-7. Only for 5 days! Because the cycle I took it was also the cycle I became pregnant, I didn't take anymore. I feel that 5 days is not likely to do significant harm. According to Web Md, "Taking dietary supplements with soy extracts is POSSIBLY SAFE when used short-term (up to 6 months). Long-term use of high doses of soy dietary supplements is POSSIBLY UNSAFE" (Soy, 2016). I was diagnosed with Graves that is causing me to have hyperthyroidism. The articles below discusses Soy leading to hypothyroid. So I do not believe using Soy is what caused me to get Graves. A study in The Journal of Clinical Endocrinology and Metabolism reported "that researchers fed some subjects 16 mg of Soy Isoflavones, the amount found in a typical vegetarian diet. Others 2 mg of Soy Isoflavones found in most omnivore's diets. The subjects fed 16 mg were 3x mo...