Narrative Review: Impact of Genetic Variability ofCYP1A2,ADORA2A, andAHRon Caffeine Consumption and Response

Background: Caffeine, which is found in a number of foods and beverages, elicits a variety of physiological responses, some of which are considered favorable such as improved alertness and reduction in fatigue, whereas others are less desirable such as heart palpitations, increased anxiety, and trouble sleeping. Consumption of the same amount of caffeine can have different effects in different people, and variation in genes is one factor thought to contribute to these differences. Single nucleotide polymorphisms (SNPs) in cytochrome P450 1A2 (CYP1A2; rs762551), adenosine A2A receptor (ADORA2A; rs5751876), and aryl-hydrocarbon receptor (AHR; rs4410790) have known links to caffeine consumption, metabolism, and postconsumption effects and responses and hence may contribute to individual variation in caffeine-related effects. Objective: To investigate the evidence that genetic variation in the genes CYP1A2, ADORA2A, and AHR are either individually or in combination associated with caffeine consumption patterns and postconsumption responses. Results: Increased coffee consumption has been linked to carriers of the CYP1A2 AA genotype, and also to those with at least one C allele in the AHR gene. Individuals with the ADORA2A T allele are predisposed to caffeine-induced anxiety, whereas the C allele predisposes to caffeine-induced sleep disturbances. Conclusions: A complex relationship exists between caffeine consumption and response, some of which are linked to genetic variation in the genes CYP1A2, ADORA2A, and AHR. However, a number of other factors are also involved with a major one being an individual's capacity for choice.