Low zinc intake increases apparent oxidation of linoleic and alpha-linolenic acids in the pregnant rat.

Dietary zinc deficiency impairs desaturation and elongation of linoleic acid, but nothing is so far known about its effects on net whole-body utilization of linoleic or alpha-linolenic acids. By measuring intake, whole-body accumulation, and excretion of linoleic and alpha-linolenic acids, together with accumulation of their long-chain products, we hypothesized that a quantitative estimate could be obtained of their whole-body disappearance (apparent oxidation). This was evaluated in pregnant and non-pregnant rats given a low-zinc diet (3.4 vs. 34 mg zinc/kg diet in zinc-adequate controls). In the nonpregnant controls, low zinc intake did not significantly affect food intake or weight gain but did reduce whole-body accumulation of desaturated and (or) elongated products of linoleic and alpha-linolenic acids. In pregnant rats, low zinc intake reduced food intake and weight gain and doubled whole-body disappearance of linoleic and alpha-linolenic acids relative to that in the zinc-adequate controls. In contrast to the maternal fatty acid changes, low zinc intake had no significant effect on linoleic acid accumulation in the fetuses. We conclude that low zinc intake during pregnancy prevents the normal accumulation of long-chain fatty acids and differentially depletes maternal whole-body stores of linoleic and alpha-linolenic acids.