The interaction with iodine metabolism following ingestion of Allium cepa (onion) and Allium sativum (garlic) by albino Wistar rats have been studied. The determination of the effect of the oral administration of onion and garlic extract on thyroid hormones (triidothyronine,T3, thyroxine,T4 were studied. The mean values of triiodothyronine (T3) for the experimental animals were 1.23 ± 0.09ng/ml for the control group and 0.97 ± 0.13ng/ml for iodine treated high dose garlic group. Compared to the control, administration of onion and garlic led to a statistically significant (P < 0.05) decrease in T3 of both normal and iodine treated rats. The mean values of thyroxine, T4, for the experimental animals was found to be 1.19 ± 0.12 IU/ml and 0.85 ± 0.16 IU/ml for the low dose onion normal rats and low dose garlic normal rats respectively. Except for the groups administered with low dose onion, oral administration of onion and garlic extract led to a significant ( P < 0.05) decrease in the thyroxine level of both normal and iodine treated rats. These results are discussed in relation to the harmful and beneficial effects of onion and garlic consumption to public health.
