The intracellular fatty acid-binding proteins (FABPs) belong to a multigene family with nearly twenty identified members. FABPs are divided into at least three distinct types, namely the hepatic-, intestinal- and cardiac-type. They form 14-15 kDa proteins and are thought to participate in the uptake, intracellular metabolism and/or transport of long-chain fatty acids. They may also be responsible in the modulation of cell growth and proliferation. Intestinal fatty acid-binding protein 2 gene contains four exons and is an abundant cytosolic protein in small intestine epithelial cells. This gene has a polymorphism at codon 54 that identified an alanine-encoding allele and a threonine-encoding allele. Thr-54 protein is associated with increased fat oxidation and insulin resistance.
Thr54 allele of FABP2 has associations with lower adjusted resting metabolic rate and early onset of obesity in Japanese obese women.()
Steady state plasma glucose concentrations were significantly higher in Ala54Thr subjects after the a diet high in short chain fatty acids (SFA) than after a high carbohydrate diet (CHO) or the Mediterranean diet. The plasma free fatty acid concentrations in these subjects were significantly lower after the CHO and high-monounsaturated fatty acid (MUFA) 'Mediterranean diets' than after the SFA diet. However, no significant differences between the 3 diets were observed in the Ala54 allele homozygotes. Insulin sensitivity decreased in subjects with the Thr54 allele of the FABP2 polymorphism when SFAs were replaced by MUFAs and carbohydrates.()