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

Abstract

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.

Major Depression and Activation of The Inflammatory Response System

“…Most importantly, there were significant and positive correlations between serum Zn and C20: 5o)3 and C22:6o)3 fractions in phospholipids; and significant inverse correlations between serum Zn and the i:o)6/So)3, C20:4o)6/C20:5o)3, and C22: 5o)6/C22: 6o)3 ratios in phospholipids (Maes et al, unpublished data). In the rodent, lowered intake of Zn does not affect food intake or weight gain but reduces whole-body accumulation of desaturated and elongated products of linoleic acid (C18:2o)6) and a-linolenic acid (C18:3o)3) (Cunnane, Yang, & Chen, 1993). Desaturase enzymes require Zn as cofactor (Russo, Olivieri, Girelli, Guarini, Pasquallini, Azzini, & Corrocher, 1997).…”

Breast‐fed infants achieve a higher rate of brain and whole body docosahexaenoate accumulation than formula‐fed infants not consuming dietary docosahexaenoate

“…Thus, a combination of increased β-oxidation and impaired desaturation-chain elongation during adverse nutritional or metabolic conditions (30,32) is an important reason for providing an apparent surplus of pre-formed DHA because α-LnA cannot be relied upon to be available for DHA synthesis when fatty acid oxidation increases. This diversion of α-LnA toward oxidation and impairment of desaturation-chain elongation (30) may contribute to the DHA deficit in the brain when dietary DHA is not provided.…”

Zinc deficiency impairs whole body accumulation of polyunsaturates and increases the utilization of [1-14C]linoleate for de novo lipid synthesis in pregnant rats

“…40060). The fatty acid composition of the soybean oil was analysed in our laboratory by capillary gas chromatography (Chen and Cunnane 1993) and contained (wtw) 10.3 % palmitate (16:0), 6.2 % pdmitoleate (16:ln-7), 3.8% stearate (18:0), 22.8% oleate (18:ln-9), 5 1 -0 % linoleate, and 7 -0 % a-linolenate but no 8a -6 or n -3 LC-PUFAs. The diets also contained supplemental biotin (440 pgtkg diet) to prevent potential biotin deficiency due to avidin in the egg white.…”

“…F d intake was recorded daily and, on a dry food basis, was adjusted gradually from 10.0 to 12.5 g 100 g-I body weight -day-I as pregnancy progressed from day 10 to term. The level of food intake was gauged from our previous study involving similar parameters in which rats consumed the same diet ad libitum but in a conventional dry, powdered form (Cunnane et al 1993). The diet was gavaged 8 timestday at 2-h intervals (08:8CB-22:00), Tap water was available at d l times.…”

“…However, during pregnancy, lower voluntary food intake caused by dietary zinc deficiency is more difficult to avoid (Cunnane et al 1993). To overcome this problem, we have implemented the short-term, tube-feeding approach, which prevents depressed food intake by providing both controls and experimental animals with adequate and equal energy and nutrient intake.…”