Differences between polyunsaturated fatty acid status of non-institutionalised elderly women and younger controls:: a bioconversion defect can be suspected

Objective: To evaluate the polyunsaturated fatty acid (PUFA) status in non institutionalised elderly women and to detect a possible essential fatty acid bioconversion defect. Design and subjects: The fatty acid composition of total plasma lipids, plasma triglycerides (TG), cholesterol esters (CE), phospholipids (PL), and erythrocytes was determined by capillary column gas-liquid chromatography in a sample of 200 non-institutionalised healthy elderly women over 75 years of age. The data were compared with those of a control group of 50 young female volunteers aged 20-48 y. Results: In elderly women, the n-6 series precursor, linoleic acid(18:2 n-6), was lower in TG and CE (P = 0.029 and 0.014, respectively). In CE, this fatty acid was highly correlated with vegetable and vegetal far intakes (P < 0.0001), suggesting a lower dietary supply than in controls, Higher percentages of 16:1 n-7 were found in all the plasma lipid fractions in elderly women, especially in CE (P < 0.0001). The ratios 20:4 n-6/20:3 n-6 and 22.6 n-3/20:5 n-3 were significantly lower in PL from elderly women (P < 0.005 and P < 0.002, respectively), raising the question of the efficiency of the terminal steps of 20:I n-6 and 22:6 n-3 biosynthesis. Dietary investigations in elderly women indicated that a high dietary protein intake via meat probably contributed to the supply of 20:4 n-6 and thus maintained the status of this fatty acid, despite the suspected altered biosynthesis. Conclusion: The PUFA status in the elderly women group could be more fragile and dependent on exogenous supply of long-chain PUFAs than previously suspected.