Marginal zinc deficiency lowers the lymphatic absorption of α- tocopherol in rats

Abstract

The present study was conducted to investigate whether the intestinal absorption of vitamin E is influenced by marginal zinc deficiency. Rats trained to meal feed were divided into two groups and fed a diet containing 3 mg Zn/kg [a low zinc (LZ group)] or pair-fed (PF controls a zinc-adequate diet (30 mg Zn/kg). At 5 wk, the body weight (352 ± 5 g, mean ± SD) of LZ rats was 98.5% of that of PF rats (357 ± 8 g). Rats with lymph cannula were infused at 3 mL/h via a duodenal catheter with a lipid emulsion consisting of 568 μmol triolein, 3.56 μmol α-tocopherol (αTP) and 396 μmol Na+- taurocholate in 24 mL of phosphate-buffered saline (pH 6.4). Lymph was collected hourly for 8 h. The amounts of αTP absorbed into the lymph were determined by high-performance liquid chromatography (HPLC). The hourly rate of αTP absorption was significantly lower in LZ than in PF rats. A marked difference (P < 0.05) was clearly evident even at 1 h (1.8 ± 1.2 nmol/h in LZ vs. 8.5 ± 3.0 nmol/h in PF). The peak rate of absorption was significantly lower in LZ rats (67.1 ± 16.7 nmol/h at 5 h) than in PF rats (95.9 ± 7.7 nmol/h at 4 h). The total amounts of αTP absorbed in 8 h in LZ and PF rats were 391.1 ± 54.4 nmol (11.0 ± 1.5% dose) and 613.9 ± 105.8 nmol (17.2 ± 3.0% dose), respectively. The lymphatic absorption of αTP was correlated with the amounts of PL (r = 0.77, P < 0.05) released into the mesenteric lymph. The hourly outputs of phospholipid and oleic acid also were significantly lower in LZ rats than in PF rats up to 4 h (P < 0.05). The cumulative lymphatic outputs of phospholipid (PL) were 20.1 ± 3.7 μmol/8 h in LZ and 27.0 ± 3.9 μmol/8 h in PF rats (P < 0.05). These results show that the intestinal absorption of vitamin E is affected by the zinc status of rats. This observation along with our earlier finding of a lower intestinal absorption of retinol suggests that zinc nutriture has a profound effect on the intestinal absorption and body status of lipid soluble vitamins.