The Nutrition Examination Research Digest (NERD) aims to provide rigorous, unbiased analysis of the latest and most important nutrition and supplementation studies. Click here to subscribe or login if already a subscriber .
Study under review: Caffeine, CYP1A2 genotype, and endurance performance in athletes
Introduction
Caffeine is recommended for[1] and used by athletes[2] because of its performance-enhancing effects, especially when it comes to endurance exercise performance. But not everyone benefits, and not all studies[3][4] report significant improvements in endurance exercise performance. For instance, one small study[5] reported individual improvements ranging from 5% to 87% for running and 10% to 156% for cycling.
While some of the inconsistencies across studies may be due to differences in study design, participants, and caffeine dosage, another more pervasive and less obvious culprit is interindividual differences in caffeine metabolism.
Caffeine is almost completely metabolized by cytochrome P450 1A2 (CYP1A2)[6], a liver enzyme encoded by the CYP1A2 gene[7] that is known to process drugs and toxins. A single nucleotide difference[8] at a specific location (rs762551) in the gene can change the enzyme’s effectiveness, granting individuals with an AA genotype faster caffeine metabolism than CC or AC genotype carriers.
Who and what was studied?
What were the findings?
What does the study really tell us?
The big picture
Frequently asked questions
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Other Articles in Issue #44 (June 2018)
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Interview: Marion Nestle, MPH, PhD
We discuss all things nutrition and epidemiology with preeminent researcher and author Marion Nestle.
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Counting hours, not calories: a potential prediabetes solution
Restricting eating to a few hours a day could have health benefits for people with prediabetes. But does the timing of the eating window matter?
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The effects of soy vs. animal protein supplementation on muscle mass and strength
In theory, soy protein is inferior to protein derived from animal products due to its lower relative amount of essential amino acids. But what about in practice?
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Short-term keto diets and athletic power
Keto diets can help athletes shed weight quickly. But do they also shed performance?
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Caffeinated resistance exercise may not be for everyone
This study found that only people with a certain type of gene seem to benefit from caffeine before lifting.
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Interview: Dr. Nural Cokcetin, PhD
In this interview, we pick honey researcher Nural Cokcetin’s brain about honey’s antimicrobial and prebiotic effects.
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Can you spice your way to better health with ginger?
Ginger may help with weight loss and improve metabolic markers in people with obesity or overweight.
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