Age and sex differences in the incorporation of EPA and DHA into plasma fractions, cells and adipose tissue in humans

Abstract

The aim of the present study was to determine whether age and sex influence both the status and incorporation of EPA and DHA into blood plasma, cells and tissues. The study was a double-blind, randomised, controlled intervention trial, providing EPA plus DHA equivalent to 0, 1, 2 or 4 portions of oily fish per week for 12 months. The participants were stratified by age and sex. A linear regression model was used to analyse baseline outcomes, with covariates for age or sex groups and by adjusting for BMI. The change in outcomes from baseline to 12 months was analysed with additional adjustment for treatment and average compliance. Fatty acid profiles in plasma phosphatidylcholine, cholesteryl esters, NEFA and TAG, mononuclear cells (MNC), erythrocyte membranes, platelets, buccal cells (BU) and adipose tissue (AT) were determined. At baseline, EPA concentrations in plasma NEFA and DHA concentrations in MNC, BU and AT were higher in females than in males (all P< 0·05). The concentrations of EPA in AT (P= 0·003) and those of DHA in plasma TAG (P< 0·01) and AT (P< 0·001) were higher with increasing age. Following 12-month supplementation with EPA plus DHA, adjusted mean difference for change in EPA concentrations in plasma TAG was significantly higher in females than in males (P< 0·05) and was greater with increasing age (P= 0·02). Adjusted mean difference for change in DHA concentrations in AT was significantly smaller with increasing age (P= 0·02). Although small differences in incorporation with age and sex were identified, these were not of sufficient magnitude to warrant a move away from population-level diet recommendations for n-3 PUFA.

Figure 1

Sex differences in EPA (a) and DHA (b) concentration in plasma fractions, cells and AT at 12 months following supplementation with EPA and DHA equivalent to 0, 1, 2, and 4 portions of oily fish per week. Data are mean and SD EPA (Figure 1a) or DHA (Figure 1b) as a percentage of total fatty acids at 12 months; Men open squares, women open circles. Mean ±SD DHA (as a percentage of total fatty acids) in plasma fractions and cell membranes at 12 months in men and women receiving EPA and DHA equivalent to 0, 1, 2, and 4 portions of oily fish per week.

Figure 1

Sex differences in EPA (a) and DHA (b) concentration in plasma fractions, cells and AT at 12 months following supplementation with EPA and DHA equivalent to 0, 1, 2, and 4 portions of oily fish per week. Data are mean and SD EPA (Figure 1a) or DHA (Figure 1b) as a percentage of total fatty acids at 12 months; Men open squares, women open circles. Mean ±SD DHA (as a percentage of total fatty acids) in plasma fractions and cell membranes at 12 months in men and women receiving EPA and DHA equivalent to 0, 1, 2, and 4 portions of oily fish per week.

Figure 2

Age differences in EPA (a) and DHA (b) concentration in plasma fractions, cells and AT at 12 months following supplementation with EPA and DHA equivalent to 0, 1, 2, and 4 portions of oily fish per week.. Data shown are mean and SD EPA (Figure 2a) or DHA (Figure 2b), as a percentage of total fatty acids, at 12 months; ‘young’ open circles, ‘middle’ open squares, ‘old’ open triangles. Mean ±SD DHA (as a percentage of total fatty acids) in plasma fractions and cell membranes at 12 months in ‘young’, ‘middle’ and ‘old’ age categories receiving EPA and DHA equivalent to 0, 1, 2, and 4 portions of oily fish per week.

Figure 2

Age differences in EPA (a) and DHA (b) concentration in plasma fractions, cells and AT at 12 months following supplementation with EPA and DHA equivalent to 0, 1, 2, and 4 portions of oily fish per week.. Data shown are mean and SD EPA (Figure 2a) or DHA (Figure 2b), as a percentage of total fatty acids, at 12 months; ‘young’ open circles, ‘middle’ open squares, ‘old’ open triangles. Mean ±SD DHA (as a percentage of total fatty acids) in plasma fractions and cell membranes at 12 months in ‘young’, ‘middle’ and ‘old’ age categories receiving EPA and DHA equivalent to 0, 1, 2, and 4 portions of oily fish per week.