The impact of single nucleotide polymorphisms on the absorption, distribution, metabolism, and excretion of dietary (poly)phenols: a critical systematic review

Response to (poly)phenol intake is highly variable among subjects, and genetic variants may contribute to such variability. However, evidence addressing this assumption is currently lacking. To address such shortcomings, we systematically reviewed the current literature and selected twelve studies looking at associations between the inter-individual variability in (poly)phenol bioavailability and metabolism and single nucleotide polymorphisms (SNPs) in candidate genes involved in (poly)phenol ADME (absorption, distribution, metabolism, and excretion). In total, 88 SNPs in 33 genes were studied, of which slightly more than half (n = 17) were related to drug/xenobiotic metabolism. More specifically, two were involved in absorption, seven in phase I metabolism, four in phase II metabolism, and four in excretion. The remaining 16 genes were related to steroid hormone metabolism and activity. Considering genes specifically related to (poly)phenol ADME, 16 SNPs showed significant modifying effects on urinary and/or plasma levels of phenolic metabolites and/or on their kinetic parameters. However, it was not possible to associate a particular genetic variant with a change in (poly)phenol-related ADME. Only a few studies applied stringent statistical criteria and recruited sufficiently large and diverse samples to reach solid and reliable conclusions. As such, studies employing larger samples, leveraging integrative bioinformatics approaches and genome-wide linkage, are warranted.