Ben,

I assume they will have consumed the thyroid gland because they didn't have
so  extensive histologic knowledge. (Like some butchers?)

The link between iodine and omega-3, or better DHA (docosahexaenoic acid),
is very substantial, indeed. Thyroid hormone acts through the thyroid
hormone receptor (THR).THR needs (like the vitamin D-receptor) the so called
retinoic X receptor (RXR) as partner to take effect. The natural ligand of
the RXR is   - n o t -  retinoic acid, but DHA. DHA is essential for man, in
contrast to the other omega-3 fish oil acid, EPA, which can be synthesized
of vegetable omega-3 acids like linolenic acid. One of the best known
sources of DHA is brain. About one third of th
e brain lipids consists of
DHA.Vegetables are devoid of DHA.

It is likely that goitre, which is endemic especially in alpine regions, is
not only caused by the lack of iodine in these regions far from the sea
level, but by a lack of DHA containing fatty fish, too. But this problem
should not apply to brain consuming hunters. As animals tend to concentrate
iodine from their environment, at least if they are able to survive under
such harsh conditions, a lack of iodine shouldn't be a problem for hunters
either.

roland