Background: Cell membrane fatty acid (FA) composition may play a role in human metabolic diseases. However, the modulatory effect of nutrients other than fat is poorly explored.
Objective: To investigate the effect of moderate-carbohydrate diets with different glycemic indices (GI) and a low-fat diet (LF) on red blood cell (RBC) FA membrane composition.
Design: The RBC FA profile was measured in 87 subjects from the GLYNDIET study. Participants were randomly assigned to one of the following energy-restricted diet for 6 months: moderate-carbohydrate/low-GI diet (LGI, n = 31), moderate-carbohydrate/high-GI diet (HGI, n = 30) or LF-diet (n = 26).
Results: We observed a significant increase in C20:0 and decrease in C20:3n-6 in the LGI and HGI groups compared to LF group. Compared to LF-diet, C22:4n-6 was lower after the HGI while C22:6n-3 was higher after LGI diet. Also, a tendency was found for higher concentrations of long-chain omega-3 polyunsaturated fatty acids (LCn-3PUFA) in LGI compared to HGI and LF groups. The intra-group analysis showed significantly increased levels of total monounsaturated fatty acids (MUFA) after LGI and HGI interventions, as well as a significant increase in C22:5n-6 and a decrease in LCn-3PUFA and omega-3-index after the LF diet. The decrease in C20:5n-3 after HGI and LF diets was also significant.
Conclusion: Diets with a moderate amount of carbohydrates and healthy fat, mainly with LGI, modify the RBC fatty acid membrane composition.
Keywords: Cell membrane; DHA; Dietary intervention; EPA; Fatty acids; Glycemic index.
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