DR. ANTHONY CHAFFEE: Cyanide will block iodine uptake. You have leafy green vegetables such as kale and broccoli and brussel sprouts, etc., that whole cruciferous vegetable family, they're teeming with these things, and those are the ones that people say, "Oh, these are the healthiest." Those are the ones that are going to trash your thyroid pretty quickly.

There is a study showing that black beans block out up to 75% of zinc absorption, and that corn tortillas can block out 100% of zinc absorption.  So zinc is required for the conversion of T4 into T3. People are saying, "Oh my T3 is going down."  Okay, what about your zinc?  --Dr. Anthony Chaffee

Even Long-Term Carnivores Are Eating Carbs Again (Here's Why)

7:05  But there's an entire category of plant toxins called goitrogens that cause a goiter, which is a swollen, irritated thyroid which is dysfunctional.  Now, you're getting thyroid dysfunction from that.  Many of them will block out iodine uptake into the thyroid.  Iodine is required to make thyroid hormone.  And the soil is pretty deficient in iodine anyway.  In Australia, it's extremely deficient.  So almost every single person that I test their blood work on, unless they're eating a lot of fish and seafood, they will be deficient in iodine.  And now you compound that with a blockade of iodine . . . almonds have cyanide.  Cyanide will block iodine uptake.  You have leafy green vegetables such as kale and broccoli and brussel sprouts, etc., that whole cruciferous vegetable family, they're teeming with these things, and those are the ones that people say, "Oh, these are the healthiest."  Those are the ones that are going to trash your thyroid pretty quickly.

And so you're getting rid of these things and then you're getting all the nutrients that you actually need in an unimpeded, bioavailable form.  So you're getting iodine; you're not blocking it out with goitrogens.  You're getting zinc and you're not blocking it out with fetic acid and other anti-nutrients.  And you're getting selenium and you're able to make sure that and you're able to absorb that as well all of these nutrients and many more are required for normal thyroid hormone production.  And when you eat plants, you're blocking a lot of those out; you're just not getting them in bioavailable form.  There is a study showing that black beans block out up to 75% of zinc absorption, and that corn tortillas can block out 100% of zinc absorption.  So zinc is required for the conversion of T4 into T3. People are saying, "Oh my T3 is going down."  Okay, what about your zinc?  People know about selenium, but they never think about zinc.   We have studies showing and also just physiology textbooks that if you're in a ketogenic state, you don't need as much T3 to produce the exact same amount of ATP energy in order to make ATP, the glucose molecule. You get about 30-32 ATP molecules per glucose molecule

SAMA HOOLE: Broccoli also contains lectins that irritate your gut and oxalates that stress your kidneys. Nutritionally it provides incomplete protein and minerals your body struggles to absorb.

Broccoli is the poster child for "eat your vegetables."
It's also systematically destroying your thyroid.

Broccoli contains goitrogens, compounds that block iodine absorption and interfere with thyroid hormone production. Specifically glucosinolates that break down into… pic.twitter.com/21uyTdvWQk

— Sama Hoole (@SamaHoole) December 4, 2025

Broccoli is the poster child for "eat your vegetables." It's also systematically destroying your thyroid. Broccoli contains goitrogens, compounds that block iodine absorption and interfere with thyroid hormone production. Specifically glucosinolates that break down into thiocyanates, isothiocyanates, and nitriles. Your thyroid needs iodine to function. Broccoli says no. Regular consumption can lead to hypothyroidism, goiter formation, metabolic slowdown, weight gain despite eating clean, and chronic fatigue. You're doing everything right according to the nutritionist and still gaining weight. Maybe check your cruciferous vegetable intake. Everyone says cooking deactivates the goitrogens. It reduces them partially at best, and you've just destroyed the heat-sensitive vitamin C you were supposedly eating it for anyway. Broccoli also contains lectins that irritate your gut and oxalates that stress your kidneys. Nutritionally it provides incomplete protein and minerals your body struggles to absorb. Your thyroid medication isn't working as well as it should because you're eating superfoods that suppress the organ it's trying to support. Brilliant strategy.