Abstract
Regular coffee intake has been associated with reduced risk of developing serious chronic diseases. The hypothesis of this study is that coffee consumers present a particular pattern/trend of genotypes that ultimately will shed light on new gene targets to treat the diseases, from which regular coffee intake has preventive effects. Sixteen SNPs identified at genome-wide association studies (GWAS) on coffee and caffeine consumption were genotyped using real-time restriction-fragment length polymorphism-polymerase chain reaction (RT-PCR). The DNA samples were the same from a previous pilot study where 15 healthy volunteers donated two blood samples collected before and after drinking a standard cup of coffee and had caffeine plasma levels and CYP 1A2 genotype (rs762551) determined. The cross-examination of the data showed that six of the sixteen SNPs exhibited a negative allelic effect direction and nine of them showed a positive effect direction of which three of them had results confirmed by a recent GWAS. There is a need of a more in-depth study to understand the effects of the presence or absence of specific variant alleles as players to benefit the health of coffee consumers.
Highlights
Coffee is the most widely consumed beverage in the world with known health benefits [1].Besides caffeine (0.5–1.0% of green coffee beans) [2], a well-known CNS stimulant, coffee contains a very complex mixture of organic compounds, such as chlorogenic acids, caffeic acid, kahweol, trigonelline, and minerals
The objective of the present study is to examine the relationship between 16 SNPs found to be significantly associated with coffee and caffeine consumption through genome-wide association studies (GWAS) within a small sample of volunteers
We observed that the two volunteers with the lowest levels of caffeine (0 and 0.01 mg/mL), who presented a fast metabolizer phenotype (CYP1A2-rs762551-A allele) for caffeine in the pilot study, showed a low to very low frequency of homozygote variant allele for all the 16 SNPs associated with coffee and caffeine consumption
Summary
Coffee is the most widely consumed beverage in the world with known health benefits [1].Besides caffeine (0.5–1.0% of green coffee beans) [2], a well-known CNS stimulant, coffee contains a very complex mixture of organic compounds, such as chlorogenic acids, caffeic acid, kahweol, trigonelline, and minerals. Individuals presenting with homozygous variant CYP1A2 (rs762551-C allele) are slow caffeine metabolizers, whereas individuals who are carriers of CYP1A2 (rs762551-A allele) are fast metabolizers [5,6]. In a previous pilot study, we aimed to determine if the genetic variability of caffeine metabolism could influence coffee consumption. The study showed that 8 out of 11 healthy volunteers (two samples were mishandled and were not tested) presented a fast metabolizer phenotype and displayed a large variability in their caffeine levels (0–0.67 mg/L). One volunteer presented a slow metabolizer phenotype and the highest caffeine blood levels (1.1 mg/mL) [7]. The study confirmed the relationship between genotype/phenotype and blood levels of caffeine, as well as the prevalence of the fast metabolizer phenotype in the population (see column 1 for caffeine plasma levels and SNP # 9 for caffeine metabolism genotype on Figure 1). The study could not reach any conclusion about the relationship between genotype and coffee consumption due to the small sample size
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