ApoE genotype: from geographic distribution to function and responsiveness to dietary factors.
ApoE is a key protein in lipid metabolism with three major isoforms. ApoE allele frequencies show non-random global distribution especially in Europe with high apoE ε3 frequency in the Mediterranean area, whereas the apoE ε4 genotype is enriched in Northern Europe. The apoE ε4 genotype is one of the most important genetic risk factors for age-dependent chronic diseases, including CVD and Alzheimer's disease (AD). The apoE polymorphism has been shown to impact on blood lipids, biomarkers of oxidative stress and chronic inflammation, which all may contribute to the isoform-dependent disease risk. Studies in mice and human subjects indicate that the apoE ε3 but not the apoE ε4 genotype may significantly benefit from dietary flavonoids (e.g. quercetin) and n-3 fatty acids. Metabolism of lipid soluble vitamins E and D is likewise differentially affected by the apoE genotype. Epidemiological and experimental evidence suggest a better vitamin D status in apoE ε4 than ε3 subjects indicating a certain advantage of ε4 over ε3. The present review aims at evaluation of current data available on interactions between apoE polymorphism and dietary responsiveness to flavonoids, fat soluble vitamins and n-3 fatty acids. Likewise, distinct geographic distribution and chronic disease risk of the different apoE isoforms are addressed.