Polymorphisms of the fatty acid desaturase gene cluster (FADS) have been associated with LDL, HDL and triglyceride concentrations. Because FADS converts α-linolenic acid and linoleic acid into long-chain polyunsaturated fatty acids (PUFA), we investigated the interaction between different PUFA intakes and the FADS polymorphism rs174547 (T>C) on fasting blood lipid and lipoprotein concentrations.

We included 4,635 individuals (60% females, 45-68 years) from the Swedish population-based Malmoe Diet and Cancer cohort. Dietary intakes were assessed by a modified diet history method including 7-day registration of cooked meals. The C-allele of rs174547 was associated with lower LDL concentration (P=0.03).

We observed significant interaction between rs174547 and long-chain ω-3 PUFAs intakes on LDL (P=0.01); the C-allele was only associated with lower LDL among individuals in the lowest tertile of long-chain ω-3 PUFA intakes (P<0.001). In addition, significant interaction was observed between rs174547 and the ratio of α-linolenic and linoleic fatty acid intakes on HDL (P=0.03).

However, no significant associations between the C-allele and HDL were detected within the intake tertiles of the ratio.

Our findings suggest that dietary intake levels of different PUFAs modify the associated effect of genetic variation in FADS on LDL and HDL.