Association of plasma fatty acid composition with plasma irisin levels in normal weight and overweight/obese children.

BACKGROUND: Irisin has been suggested to protect against overweight. There are no previous data on the association of plasma fatty acid (FA) composition with plasma irisin.

OBJECTIVES: We studied the association of FA composition with plasma irisin in normal weight and overweight/obese children.

METHODS: This cross-sectional study included pre-pubertal children (388 normal weight children and 55 overweight/obese children); 6-9 years of age, taking part in the Physical Activity and Nutrition in Children Study. After an overnight fast, we measured plasma FA composition by gas chromatography and plasma irisin levels by enzyme-linked immunosorbent assay.

RESULTS: Higher proportion of total monounsaturated fatty acids in plasma cholesteryl esters (CEs) (β = 0.139, P = 0.003) and phospholipids (PLs) (β = 0.147, P = 0.002) and lower proportion of total polyunsaturated fatty acids in plasma CE (β = -0.130, P = 0.006) and PL (β = -0.165, P < 0.001) were associated with higher plasma irisin level in the whole study group. The association of plasma FA composition with plasma irisin level was stronger among overweight/obese children compared to normal weight children. Higher proportion of γ-linolenic acid (β = 0.324, P = 0.017) and lower proportion of linoleic acid (β = -0.397, P = 0.005) in plasma CE were related to higher plasma irisin level among overweight/obese children, indicating the direct association of estimated D6D activity in plasma CE (β = 0.343, P = 0.011) with plasma irisin. Furthermore, higher proportion of oleic acid in plasma CE (β = 0.345, P = 0.012) and PL (β = 0.292, P = 0.033) and higher proportion of adrenic acid (β = 0.366, P = 0.008) and docosapentaenoic acid (β = 0.351, P = 0.010) in plasma PL were associated with higher plasma irisin level among overweight/obese children.

CONCLUSION: Metabolically unfavourable plasma FA profile was associated with higher plasma irisin level especially in overweight/obese children, suggesting that excess body fat might modulate these relationships.