Fatty acid status and antioxidant defense system in mothers and their newborns after salmon intake during late pregnancy

Highlights

• To our knowledge, this is the first study on the antioxidant system in newborns from pregnant women consuming oily fish.

• The appropriate intake of oily fish during pregnancy avoids an imbalance of ω-3/ω-6 ratio

• Oily fish is an adequate way to provide ω-3 long-chain polyunsaturated fatty acids during pregnancy

Abstract

Objective

The aim of the present study was to assess the maternal and newborn status of erythrocyte fatty acids and the antioxidant defense system after the intake of two portions of salmon per week during late pregnancy.

Methods

Pregnant women (N = 123) were randomly assigned to continue their habitual diet, which was low in oily fish (control group, n = 61) or to consume two 150-g salmon portions per week (salmon group, n = 62) beginning at 20 wk of gestation and lasting until delivery. Fatty acids, selenium, and glutathione concentrations and antioxidant defense enzyme activities were measured in maternal erythrocytes at 20, 34, and 38 wk of pregnancy, and in cord erythrocytes collected at birth. Plasma concentrations of antioxidant molecules were measured.

Results

Compared with the control group, consuming salmon had little effect on erythrocyte fatty acids in either mothers or newborns. Components of the antioxidant defense system did not differ between groups. Glutathione peroxidase activity and the concentrations of tocopherols, retinol, and coenzyme Q10 were significantly lower in cord blood compared with maternal blood at week 38 in both groups.

Conclusion

Maternal and newborn erythrocyte fatty acids are not strongly affected by the intake of two portions of salmon per week during the second half of pregnancy, although erythrocyte docosahexaenoic acid might be increased in newborns. Maternal and newborn antioxidant defense systems are not impaired by intake of salmon from 20 wk gestation.

Introduction

The requirements for the long-chain polyunsaturated fatty acids (LC-PUFA) arachidonic acid (AA, C20:4 ω-6) and docosahexaenoic acid (DHA, C22:6 ω-3) are especially high during the last trimester of pregnancy and the first weeks of extrauterine life because of their accretion into the growing brain and other tissues [1], [2]. AA and DHA can be formed by elongation and desaturation of the essential precursors linoleic acid (LA; C18:2 ω-6) and α-linolenic acid (ALA; C18:3 ω-3), respectively, but fetal fatty acid-desaturase enzymes are unable to supply sufficient LC-PUFA until 16 wk after birth [3]. Therefore, fetal LC-PUFA must be supplied from the maternal circulation and so are ultimately derived from the maternal diet.

The increased fetal demand for LC-PUFA is indicated by a concomitant decrease in the relative concentrations of DHA and AA in the maternal plasma as pregnancy progresses [4], [5]. Fish oils rich in ω-3 LC-PUFA, DHA and eicosapentaenoic acid (EPA; 20:5 ω-3), may enhance maternal, fetal, and neonatal PUFA status. Findings from several studies have shown that dietary intakes of ω-3 LC-PUFA of ≥2.6 g/d significantly increase the ω-3 LC-PUFA status in both pregnant women and their newborns [6], [7], [8]. Nonetheless, this increase may be accompanied by a reduction of ω-6 LC-PUFA toward the end of pregnancy [8], [9], [10], [11], and this is not desirable.

The UK government recommends that pregnant women consume one or two portions of oily fish each week as a source of ω-3 LC-PUFA [10]. It is not clear whether consumption of fish as a whole food delivering ω-3 LC-PUFA affects the ω-3 LC-PUFA status of mothers and their newborns. In this regard, one study observed higher EPA and DHA status and lower AA status in mothers with high dietary intake of oily fish in relation to those with lower consumption, with similar findings in newborns [11]. To our knowledge, no intervention studies apart from Salmon in Pregnancy Study (SiPS) [12] have investigated the effect of higher oily fish intake in pregnant women whose consumption of oily fish was normally low. In SiPS, the intake of two portions of salmon per week (equivalent to a daily intake of about 500 mg EPA + DHA) resulted in an enhanced plasma EPA and DHA status in pregnant women, and a higher EPA and DHA status in the umbilical cord blood plasma than seen in the control group [12].

It is known that LC-PUFAs are good substrates for lipid peroxidation, and so a diet high in ω-3 LC-PUFA could contribute to oxidative stress [13]. However, several mechanisms exist to protect against peroxidative damage. These mechanisms involve exogenous vitamins and trace elements as well as endogenous enzyme systems [14]. In SiPS, maternal oxidative stress markers remained unaffected after consumption of two portions of salmon per week [15]. Furthermore, maternal retinol and selenium (Se) levels were significantly higher in the group supplemented with salmon than in the control group [16]. To our knowledge, there are no studies on the effect of increased maternal oily fish intake on the antioxidant defense system in newborns.

Therefore, the aims of the present study, as part of SiPS, were to examine the effect of increased salmon consumption beginning in week 20 of pregnancy through delivery (1) on erythrocyte fatty acids in pregnant women and their newborns and (2) on the antioxidant defense system in the newborns' blood.