Background:
Together with adiposity, plasma fatty acid (FA) composition can modulate the development of the metabolic syndrome (MS).

Objective:
Our aim was to investigate the relations of FA composition in plasma phospholipids and cholesterol esters (CEs) with weight status, MS, and inflammation in adolescents.

Design:
Plasma FA composition was measured by gas-liquid chromatography in 120 (60 normal-weight and 60 overweight) 12-y-old adolescents.
We also measured the presence of MS, insulin resistance with the homeostasis model assessment, and interleukin 6 and C-reactive protein concentrations in the adolescents.

Results:
MS was present in 25% of the overweight adolescents but in none of the normal-weight adolescents.
Compared with overweight adolescents, normal-weight adolescents had lower saturated FAs (SFAs) in both phospholipids (P < 0.001) and CEs (P < 0.01) and higher docosahexaenoic acid in phospholipids (P < 0.001). In overweight subjects, FA composition was associated with MS features independent of body fat.

The odds ratios of MS for a 0.1 increase in the ratio of polyunsaturated FAs (PUFA) to SFAs (PUFA:SFA) were 0.91 in phospholipids (P = 0.03) and 0.90 in CEs (P = 0.06). In phospholipids, PUFA:SFA and linoleic acid were associated positively with HDL cholesterol (P < 0.01 for both).
PUFA:SFA in phospholipids and CEs were associated inversely with interleukin 6 (P < 0.05 for both).

Eicosapentaenoic acid in phospholipids (P = 0.06) and CEs (P < 0.05) and linolenic acid in CEs (P < 0.05) were inversely related to C-reactive protein.
These relations remained significant after adjustment for the waist-to-hip ratio.
No significant relation between FA composition and the homeostasis model assessment was observed.

Conclusions:
Plasma FA composition is associated with weight status in healthy adolescents. High intake of long-chain PUFAs, especially n-3 PUFAs, may protect obese subjects against MS and low-grade inflammation as early as adolescence.