Background: PUFAs, especially from vegetable fat sources, have been suggested to contribute to weight regulation and be protective to cardiometabolic health. However, a few longitudinal studies on childhood exposure are available, with short follow-up time and conflicting results.

Objectives: To study the relationship between plasma proportions of PUFA in childhood and adolescence and cardiometabolic risk factors in young adulthood, such as obesity, body composition, blood pressure (BP), and blood lipids in a prospective cohort study.

Methods: We included n = 688 participants of the BAMSE (Barn, Allergi, Miljo<euro>, Stockholm, Epidemiologi) cohort in Stockholm, Sweden, with data on plasma phospholipid proportions of n-3 and n-6 fatty acids [alpha-linolenic acid (ALA), EPA, docosapentaenoic acid, DHA, linoleic acid (LA), and arachidonic acid (AA)] at 8 and 16 y and body mass index (BMI), waist circumference, fat mass %, BP, and blood lipids at 24 y. Associations between PUFAs and cardiometabolic health outcomes were assessed with sex-stratified multivariable-adjusted linear and logistic regression models.

Results: In females, LA and ALA at 16 y were inversely associated with BMI [B:-0.35 (-0.54,-0.17) and B:-6.1 (-11,-1.5), respectively], and similarly with waist circumference and fat mass at 24 y. Also in females, LA was inversely associated with BP, triglycerides, LDL-cholesterol), and total cholesterol (e.g., B-0.044 [-0.079,-0.0099] for LA at 16 y and LDL-cholesterol), whereas ALA was only inversely associated with LDL-cholesterol. No associations were found between long chain n-3 fatty acids or AA and any of the studied outcomes.

Conclusions: Plasma phospholipid proportions of LA and ALA, biomarkers of vegetable oil intake, during childhood and adolescence were inversely associated with measures of obesity and cardiometabolic health in young adulthood, with a potential sex difference. These findings accord with short-term feeding trials suggesting a possible preventive role of LA on body fat accumulation.