The thyroid gland produces thyroid hormones. The thyroid hormones are designated T4 and T3. The T3 thyroid hormone is the most active and is the main stimulatory of metabolic activity in cells. In contrast, T4 is relatively inactive, but can be converted to T3 in the liver, thereby increasing its effects. The amount of circulating T3 therefore has important consequences for weight loss and in the maintenance of correct body weight.
A number of dietary conditions are known to cause low thyroid hormone production. One of these conditions is a deficiency of the essential mineral iodine. Iodine is important for thyroid hormone production because the mineral makes up part of the structure of the thyroid hormones. Low levels of iodine in the diet cause goitre, a condition where the thyroid gland swells. This used to be called Derbyshire neck, on account of the high prevalence in the county of Derbyshire.
However, iodine deficiency is now exceedingly rare in Western nations and goitre is consigned largely to the medical textbook. However, although it is unlikely that a dietary deficiency of iodine will develop thanks to the addition of iodine to table salt, other dietary factors can produce sub-optimal thyroid function. Dietary goitrogens are substances that interfere with thyroid hormone production, and they are more common in the average diet than might be considered.
The Cabbage Family
The cabbage family of vegetables includes the cabbage, broccoli, watercress, kale (collards), brussel sprouts and cauliflower. These vegetables are very beneficial for the health because they contain anti-cancer compounds. Recommendations are therefore to eat more of this family of vegetables in the diet. However, the cabbage family also contains goitrogens and in this regard some evidence suggests they may interfere with thyroid function.
Cooking is The Answer
The goitrogens in cabbage family vegetables can be deactivated through cooking. Eating the cooked products of these vegetables is therefore safe and will not cause thyroid problems. However, evidence suggests that moderate consumption of raw cabbage family vegetables does not cause thyroid problems in normal healthy individuals with adequate iodine intake. Therefore eating raw cabbage in salads for example should not be a problem if moderated.