Goitrogenic vegetables are cruciferous vegetables that, when eaten raw and in large quantities, can slow down your thyroid gland and make you hypothyroid. Common goitrogenic foods include kale, broccoli, spinach, cabbage, and Brussels sprouts. You can eat these healthy foods. Just make sure that you steam or cook them to reduce their thyroid-slowing properties. And be careful about overdoing raw smoothies made with these vegetables.