Supplementation with trans fatty acid at 1% energy did not increase serum cholesterol irrespective of the obesity-related genotypes in healthy adult Japanese.

Background And Objectives: The excessive intake of trans fatty acids increases serum low-density lipoproteincholesterol and reduces high-density lipoprotein-cholesterol. We studied the effects of 1% energy trans fatty acid supplementation on serum lipid concentrations in healthy adult Japanese with different obesity-related gene polymorphisms.

Methods And Study Design: A randomized, double-blind, parallel trial was conducted in 53 healthy adults. The volunteers consumed one cookie containing either 1% energy or <0.01% energy (control) of trans fatty acids every day for 4 weeks, and a blood sample was then obtained after overnight fasting. The single nucleotide polymorphisms of the fat mass- and obesity-associated gene rs9939609 and beta-3 adrenergic receptor rs4994 were genotyped.

Results: The mean trans fatty acid intake of the control and trans fatty acid groups corresponded to 0.28% and 1.31 % energy, respectively. There were no significant differences in serum cholesterol (total, low-density lipoprotein and high-density lipoprotein) or triacylglycerol between the control and trans fatty acid groups. The responses of serum cholesterol, triacylglycerol, glucose, insulin and hemoglobinA1c were also independent of the fat mass- and obesity-associated gene and beta-3 adrenergic receptor gene variants.

Conclusions: Our findings indicate that supplementation with 1% energy trans fatty acids has little effect on serum cholesterol in healthy adult Japanese, regardless of genotype of fat mass- and obesity-associated gene or beta-3 adrenergic receptor. More systematic studies, with respect to dietary trans fatty acid intakes above those used here, may be warranted to determine the tolerable upper level of dietary trans fatty acid.