A Correlation Study of DHA Intake Estimated by a FFQ and Concentrations in Plasma and Erythrocytes in Mid- and Late Pregnancy

Abstract

Adequate docosahexaenoic acid (DHA) is essential for the optimal growth and development of the fetus. Maternal DHA content fluctuates during pregnancy. The correlation of DHA content with dietary intake might be varied over the course of pregnancy. We aimed to compare the dietary DHA intake, estimated by a DHA-specific semiquantitative food frequency questionnaire (FFQ) against its blood content, among mid- and late-term pregnant women. A total of 804 Chinese pregnant women completed the tailored FFQ and provided fasting venous blood samples. Dietary DHA intake (mg/day) in the previous month was calculated from the FFQ using Chinese Food Composition Table. DHA concentrations (weight percent of total fatty acids) in plasma and erythrocytes were measured by capillary gas chromatography. Spearman correlation coefficients (r_s) between DHA intake and its relative concentrations were calculated. After adjustment for maternal age, pre-pregnancy body mass index, stage of pregnancy, parity, education level, ethnicity, and annual family income per capita, the correlation coefficients of DHA intake with its concentrations in plasma and erythrocytes were 0.35 and 0.33, respectively (p < 0.001). The correlations were relatively stronger among women in late pregnancy (r_s = 0.44 in plasma and 0.39 in erythrocytes) than those in mid-pregnancy (r_s = 0.25 and 0.26). The significant correlations were consistently observed in subgroups stratified by regions, except for erythrocytes in women living in a coastland area. Multiple regression analyses also indicated significant positive linear correlations between DHA intake and its plasma or erythrocytes concentrations (p < 0.001). In conclusion, dietary DHA intake, estimated by the FFQ, was positively correlated with its concentrations in plasma and erythrocytes in Chinese pregnant women, especially for women in late pregnancy, with the exception of the erythrocytes of those living in a coastland area.

Keywords: docosahexaenoic acid; erythrocytes; food frequency questionnaire; plasma; pregnant women.

Figure 1

Relation between dietary DHA intake and its concentrations in plasma and erythrocytes among overall women (a), mid-term pregnant women (b) and late-term pregnant women (c). Deciles of DHA intake were adjusted for maternal age, pre-pregnancy body mass index, stage of pregnancy, parity, education level, ethnicity and annual family income per capita. DHA concentrations are least squares means; bars represent 95% confidence intervals. All p values for trends were < 0.001.