Abstract
The effect of long-term (7-9 months) feeding of a diet containing iodine-enriched eggs, which had considerably higher amounts of iodine than ordinary eggs, was studied on the lipid metabolism in rats. A laboratory powder chow was added at 100 (w/w) level with ordinary egg powder (Ordinary egg diet as control: 35.1μg iodine/100g diet) or iodineenriched egg powder (Iodine-enriched egg diet: 392.2μg iodine/100g diet). The animals were meal-fed twice a day and allowed to take daily voluntary running exercise in wheels for 24 hr. The long-term feeding with iodineenriched eggs did not influence body weight gain, food intake, voluntary running activity, weights of several organs and adipose tissues, and lipid concentrations in several organs and tissues. However, the serum lipid levels were decreased after the feeding of iodine-enriched eggs. A decrease in triacylglycerol (TG) level was significant (p<0.05). The long-term feeding with iodine-enriched eggs resulted in a reduced hepatic-intestinal TG production rate and also an enhanced TG removal rate from blood. Furthermore, skeletal muscle and adipose tissue lipoprotein lipase activity was significantly elevated with the feeding of iodine-enriched eggs. These results suggest that the lowering effect of blood TG level with feeding of iodine-enriched eggs may be mediated by either a reduced hepaticintestinal TG production or an enhanced peripheral removal of circulating TG. Serum total iodine concentration was 5 times higher in the iodineenriched egg fed rats as compared to controls, but the serum concentrations of thyroid stimulating hormone and thyroid hormones as well as the thyroid total iodine content were not different between the two dietary groups of animals. Thus, the present study did not demonstrate any relationship between the hypotriacylglycerolemic effect of iodineenriched eggs and the serum levels of thyroid relating hormones.
