Gene-diet interaction and plasma lipid responses to dietary intervention

Strategies for disease prevention can have a major impact on people's health. However, major gaps exist in our knowledge with regard to nutritional adequacy, nutrient-disease interactions, nutrient-gene interactions, and effective strategies for implementation of dietary recommendations which have the potential to decrease the disease burden and to contribute to successful aging of the population. Coronary heart disease is one of the major causes of mortality in the world. We have sound evidence that high levels of low-density lipoprotein cholesterol (LDL-C) and low levels of high-density lipoprotein cholesterol (HDL-C) are associated with increased risk of coronary heart disease. Lipoprotein concentrations are associated with environmental variables such as diet and lifestyle, but genetics also play a significant role. We have examined polymorphisms at candidate loci to determine their usefulness as markers for dietary responses. A G/A polymorphism 75 bp upstream from the gene encoding apolipoprotein AI (APOA1) has been described in ~ 30% of the population. Our studies show that this polymorphism is associated with variability in the HDL-C response to dietary fat, specifically to polyunsaturated fatty acids (PUFA) in the diet. Carriers of the A allele respond to increases in dietary PUFA with elevations in HDL-C levels, probably due to altered interactions of transcription factors with the mutated promoter. Therefore carriers of the A allele can potentially decrease their atherogenic risk by consuming high-PUFA diets. Likewise, we have examined the interaction between other dietary habits, such as alcohol drinking, and variability at the APOE locus, and have demonstrated that the classical associations between APOE polymorphism and LDL-C levels are observed primarily in those subjects who consume alcohol. Moreover, we have found a subgroup of the population, APOE4 carriers, for whom drinking alcohol may exert detrimental effects on lipid metabolism. This knowledge will contribute towards the development of more effective personalized dietary recommendations.