INFLUENCE OF DIETARY HABITS ON THYROID STATUS OF A NOMADIC PEOPLE, THE BORORO SHEPHERDS, ROAMING A CENTRAL AFRICAN REGION AFFECTED BY SEVERE IODINE DEFICIENCY

Objective: In contrast with the endemic goiter reported in several Afr ican countries, the nomadic Bororos of the Central African Republic ha ve an unexpectedly low prevalence of goiter. This study was conducted to elucidate this puzzling observation. Design: Thyroid function and i odine and thiocyanate intakes were evaluated in Bororos and inhabitant s of the same area and compared with an Italian population. Results: U rinary iodine concentrations indicated moderate iodine deficiency in t he rural people and the Bororos, In the latter, no individual with cli nical hypothyroidism was observed. Compared with the reference populat ion, the Bororos had slightly lower thyroxine (T-4) and free thyroxine (FT4), slightly increased tri-iodothyronine (T-3) and T-3/T-4 ratio, slightly higher TSH, normal serum thyroglobulin, a prevalence of goite r of 17.1% and a higher urinary thiocyanate. The rural people showed s triking differences: lower T-4 and FT4, increased T-3/T-4 ratio, marke dly increased TSH and thyroglobulin, a prevalence of goiter of 76.9% a nd a high urinary thiocyanate, indicating frequent consumption of cass ava. A dietary survey indicated that the Bororos ingest large amounts of milk and related products but infrequently eat cassava. Conclusion: A minute difference in iodine deficiency between two populations indu ces totally different patterns of goiter and thyroid function, The rea son for such a contrast probably involves differences in diet.