Does CYP1A2 Genotype Influence Coffee Consumption?

Research Article

Austin J Pharmacol Ther. 2015; 3(1).1065.

Does CYP1A2 Genotype Influence Coffee Consumption?

Santos RM1*, Cotta K1, Jiang S2 and Lima DRA3

1Department of Pharmaceutical Sciences, South University School of Pharmacy, USA

2Department of Biomedical Science, Mercer University School of Medicine, USA

3Instituto of Neurology, Federal University of Rio de Janeiro, Brazil

*Corresponding author: : Santos RM, Department of Pharmaceutical Sciences, South University School of Pharmacy, 709 Mall Boulevard, Savannah, GA 31406, USA

Received: November 26, 2014; Accepted: February 05,2015; Published: February 09, 2015


Coffee is the major source of caffeine in the American diet. Caffeine is 95% metabolized by CYP 1A2, which has a polymorphic genetic binomial distribution within the population. The homozygous wild type confers a fast metabolizer phenotype and the homozygous variant allele confers a slow metabolism of caffeine, the latter being the least predominant in the normal population. Our study objective was to examine whether genetic variability of caffeine metabolism (CYP 1A2) is associated with plasma caffeine levels and can influence the coffee consumption in young healthy volunteers. We found an inverse relationship between caffeine metabolization by CYP 1A2 and caffeine plasma levels at 45-60 minutes after intake of one cup of standardized brewed coffee (150 mg of caffeine). Our sample size was small (15 volunteers) but all possible genotypes were represented in accordance with the normal distribution in the population. We did not find a correlation between CYP 1A2 genotype and frequency or type of coffee selection (caffeinated or decaffeinated). We concluded that a bigger sample size is needed in order to identify a probable influence of caffeine metabolism phenotype on coffee consumption.

Keywords: Coffee consumption; Caffeine; Plasma levels; CYP1A2 genotype


The association between regular coffee intake and the risk of developing a number of disorders such as myocardial infarction [1, 2], hypertension [3-6], breast cancer [7] and Parkinson’s disease [8-10], just to name a few, has been the objective of various epidemiologic studies. All of the above mentioned studies mainly focused on the content of caffeine in coffee and considered caffeine to be the main ingredient responsible for the observed effects.

Caffeine is metabolized primarily by cytochrome P450 1A2 (CYP1A2) in the liver through an initial N-demethylation [11,12]. CYP1A2 accounts for approximately 95% of caffeine’s metabolism and shows genetic polymorphism that reflects the variability in enzyme activity between individuals [13].

An A→C substitution at position 734 (CYP1A2*1F) in the CYP1A2 gene located at 15q24, decreases enzyme inducibility; as measured by the ratio of plasma or urinary caffeine to caffeine metabolites after a dose of caffeine, resulting in impaired caffeine metabolism [11,12,14]. Carriers of the variant CYP1A2*1F allele are “slow” caffeine metabolizers, whereas individuals who are homozygous for the CYP1A2*1A allele are “fast” caffeine metabolizers [11,12,14]. However, it is not clear whether CYP 1A2 genotype alters caffeine consumption and prevents slow metabolizers from drinking coffee regularly.

The fact that caffeine is one of the most widely used CNS stimulant and coffee the major source of caffeine in our diet, probably led those who are very sensitive to the effects of caffeine/coffee, to use decaffeinated coffee or to simply reduce or even abstain from coffee intake. Additionally, the levels of caffeine in the body after coffee intake are highly variable due to at least two main reasons [15-17] . The first is related to the coffee preparation itself (type/origin of the beans, method of preparation) [18]. The second one is related to individual genetic make-up in terms of caffeine pharmacokinetic metabolization (CYP1A2) and pharmacodynamic effects on adenosine receptors (A2A). Considering all the above mentioned it is tempting to hypothesize that individuals that tend to accumulate caffeine due to slow metabolization will present increased levels of caffeine in the body. These in turn will be responsible for the adverse effects that could lead those individuals to abstain or avoid using caffeinated coffee. Another possibility would be to look at the individual intervariability on adenosine receptor, more specifically receptors A2A (ADORA2) and its possible consequences on coffee effects.


The purpose of the present study is to examine whether genetic variability of caffeine metabolism (CYP 1A2) is associated with plasma caffeine levels and can influence the coffee consumption in young healthy volunteers.

Materials and Methods


Fifteen normal volunteers enrolled in the PharmD Program at South University School of Pharmacy, Savannah, GA. participated in this pilot research project. The study group is composed of twelve females and three males aging between 22 and 43 yrs. old and with body weights ranging from 150 to 250 lbs. The enrollment in this study was random with no specific inclusion or exclusion criteria. We conducted a brief oral presentation in class explaining the purpose of the study to the students and collected signatures of possible interested participants. The subjects enrolled in this study signed an informed consent form that was previously submitted and approved by the Institutional Review Board of South University.

Coffee preparation

One hundred grams of ground, medium roast coffee was brewed using 1.5 L of spring water under conditions set at temperature controlled brewer system BrewWISE (BUNN).

Sample collection

On the day of the study, the volunteers arrived at school having fasted for at least 8 hours. The protocol involved the collection of two time-point blood samples. The first sample was time-point zero (t0) collected as soon as they arrived. The second sample (t1) was collected between 45-60 minutes after the administration of one cup of 200 ml of a standardized brewed coffee, followed by a light breakfast composed of: a bagel with cheese spread, a muffin and a cookie. The first blood sample was collected with EDTA and used to harvest DNA for genotyping. The second blood sample was collected with heparin and used to determine the plasma caffeine levels after acute coffee intake.

DNA preparation and CYP1A2 genotyping

Two ml of whole blood collected in EDTA tubes were used for genotyping. The blood sample was centrifuged at 14,300 g for 4 min at 20°C to separate the plasma from blood cells, which were used for DNA isolation by standard procedures (ArchivePure DNA Blood Kit, cat#2300740, 5-Prime, Gaithersburg, MD). After the final step of DNA hydration, the samples were kept at 4oC for short-term storage until the determination of the genotype. The DNA purity was ascertained through nucleic acid concentration determination, utilizing the absorbance spectra of 220-320 nm and calculating the ratio of A260/ A280 as a measure of purity (NanoDrop 2000C, Thermo Scientific, Wilmington, DE).

The CYP1A2 polymorphism was detected by real-time restrictionfragment length polymorphism-polymerase chain reaction (TaqMan Drug Metabolism Genotyping Assay, Applied Biosystems, Carlsbad, CA). The assay was run in duplicates (Applied Biosystems 7900HT Fast Real-Time PCR System) at the Hoskins Cancer Center, Mercer School of Medicine laboratories in Savannah, GA. Figure 1 depicts the rationale of assigning the specific alleles for each sample according with the fluorophore that is released during the PCR reaction. In our method VIC™ dye fluoresces when Allele 1 is present, which corresponds to the variant allele CYP 450 1A2*1F; when FAM™ dye fluoresces means that Allele 2 is present and corresponds to the wild type, most common form of allele, CYP 450 1A2*1A. The phenotype will depend on the presence of a heterozygous or homozygous pair of alleles. There is co-dominance for this trait so that homozygosis for the variant will determine a slow metabolizer and homozygosis for the wild-type will determine a fast metabolizer phenotype and the presence of both alleles will determine an intermediate phenotype.