The goitrogenic effect of two Sudanese pearl millet cultivars in rats

Abstract

Pearl millet ( Pennisetum americanum L. Lecke) is the staple food in many goiter areas in the west of Sudan while wheat is an additional staple food in low goiter areas. Epidemiological evidence from these areas suggests that although iodine deficiency is the major cause of goiter, millet consumption may play a role in goiter causation. This study was designed to determine in rats the possible goitrogenic and antithyroid effects of two millet cultivars, Bayoda and Balady, consumed in two endemic goiter areas with different goiter prevalence rates in the west of Sudan. Both fermented and unfermented forms of the two cultivars of millet were included in the study. Whole grain millet and wheat used in this experiment were only fortified with iodine with an amount supplying recommended dietary requirements. Feeding the two millet cultivars unfermented was associated with serum thyroid hormones comparable with the wheat reference while feeding the Balady cultivar (consumed in the area of low goiter prevalence) unfermented was associated with significant enlargement of the thyroid gland. Fermentation, was associated with the same trend of changes in both cultivars: enlargement of the thyroid gland and increased serum T4, T3 and TSH. Compared to the wheat reference group, fermentation of the cultivars was associated with increased serum T3 and T4 (only Bayoda) and significant further enlargement of the thyroid gland (only Balady). Among the animals that consumed millet (two way analysis), those receiving fermented millet showed increased serum T4, T3 and TSH compared to those which received unfermented millet. Nutritional inadequacies reflected in impaired growth, and enlarged heart and kidneys were more pronounced in animals fed millet diets than in those fed the wheat reference diet. In conclusion, in rats, the consumption of millet interferes with thyroid function; the consumption of Balady seems to induce an enlargement of the gland whereas the consumption of Bayoda causes modifications in the pattern of thyroid hormones.