Dietary intake of 18: 2n-6 and 18: 3n-3 may affect endogenous production and incorporation of n-3 long-chain PUFA (LCPUFA) from fish oils (FO). This double-blinded controlled 2 × 2-factorial 8-week intervention investigates the effects of high and low 18: 2n-6 intake in combination with FO-supplementation on tissue fatty acid composition. Healthy young men (n 64) were randomized to capsules with FO or olive oil (control) (4·4 (2·0–5·6) ml/d) and to either sunflower oil and margarine (S/B) or rapeseed oil and a butter spread (R/K) to provide a high or a low 18: 2n-6 intake. Diet was measured by 4-d weighed dietary records at baseline, during and 8 weeks after the intervention and tissue incorporation as fatty acid composition of peripheral blood mononuclear cells (PBMC). The fat intervention gave a mean difference in the 18: 2n-6 intake of 7·3 g/d (95 % CI 4·6, 10·0) and a similar 18: 3n-3 intake in the groups. The R/K groups had a 0·2 % fatty acid (FA%) (95 % CI 0·0, 0·4, P = 0·02) higher content of 22: 5n-3 in the PBMC, a tendency of slightly higher 20: 5n-3 (P = 0·06), but no more 22: 6n-3 (P = 0·83) than the S/B groups. FO effectively raised the PBMC content of all n-3 LCPUFA (P < 0·001). The fat intervention did not markedly influence the effect of FO; the mean PBMC content of n-3 LCPUFA was 10·3 (sem 0·3) FA% in the FO+S/B group and 10·6 (sem 0·2) FA% in the FO+R/K group. In conclusion, increasing the 18: 2n-6 intake did not have any pronounced effect on incorporation of n-3 LCPUFA in PBMC, either alone or with simultaneous FO supplementation.
Polyunsaturated Fatty Acid Biosynthesis Involving Δ8 Desaturation and Differential DNA Methylation of FADS2 Regulates Proliferation of Human Peripheral Blood Mononuclear Cells