soy
4 interactions related to soy
levothyroxine + soy
Soy protein and isoflavones can bind to levothyroxine in the gut and reduce its absorption, sometimes increasing dose requirements in hypothyroid patients. Case reports and systematic reviews describe rising TSH and unstable thyroid levels in patients consuming soy products close to their dose.
tempeh + levothyroxine
Tempeh is a fermented soybean cake, and soy protein binds levothyroxine in the gut and reduces its absorption, with documented decreases of 16 percent at 20 grams of soy protein and over 35 percent at 40 grams. Fermentation reduces isoflavone bioavailability but leaves intact soy protein that still interferes with thyroid hormone uptake.
edamame + levothyroxine
Edamame is whole young soybeans, and the soy protein and isoflavones bind levothyroxine in the gut and reduce its absorption, with measured drops of 16 percent at 20 grams of soy protein and over 35 percent at 40 grams. A one-cup serving of shelled edamame supplies roughly 18 grams of soy protein, enough to cause clinically meaningful interference if eaten close to the dose.
tofu + levothyroxine
Tofu is made from coagulated soy milk and is one of the most concentrated sources of soy protein in the typical diet, with roughly 20 grams of soy protein per cup. Soy protein binds levothyroxine in the gut and reduces absorption by 16 to over 35 percent depending on dose, and case reports describe TSH rising when tofu is added to a previously stable levothyroxine regimen.