Calum Gore is an expert in medical biochemistry and health and the founder of biochemical diagnostic testing services company GC Bioscience. He is based in Leicester, Leicestershire.
Coffee is one of the most popular and widely consumed beverages in the world with more than 400 billion cups drunk annually. Because of its caffeine content, the stimulant is the most commonly consumed psychoactive drug among adults.
For years research has been published extolling the health benefits of regular coffee consumption, ranging from improved cardiovascular health to a decreased risk of dementia, Alzheimer’s disease, Parkinson’s disease, and type 2 diabetes[2,3].
But there is a growing debate that for some people too much coffee can actually be detrimental to health. And it all depends on your genes. As our understanding of individual genes and genetic sequencing continues to improve, it is becoming increasingly clear that caffeinated coffee can have both medicinal and detrimental effects on health. Remember, no two people have the exact some genome, even identical twins can have different variants of genes.
The role of genes
Whether or not coffee helps or hinders your health is related to how proficient you are at metabolising caffeine. Caffeine is primarily metabolised in the liver by an enzyme encoded by the gene CYP1A2. To put it in the simplest terms, this gene instructs your liver to produce one of either two enzymes: CYP1A2 fast, which metabolises caffeine quickly and efficiently; or CYP1A2 slow, which is far less effective at breaking down caffeine.
People who express the fast enzyme may get away with coffee’s detrimental effects because caffeine is metabolised rapidly and eliminated from the body, so you experience only the positive, healthy outcome of consumption. However, if you are a slow metaboliser then caffeine is metabolised much slower and so builds up in the blood stream, which can exacerbate the negative affects, including an increase in the risk of heart disease[4-7].
The cost of caffeine
About 46% of the population are fast metabolisers, so moderate caffeine intake – 200mg to 300mg, which is two to three cups of regular filter coffee – per day has a beneficial effect by slightly reducing the risk of heart attacks. It appears that even heavy coffee consumption does not increase this risk in fast metabolisers.
For the remaining 54% of the population who are slow metabolisers, even moderate caffeine intake of two to three cups per day increases the risk of heart attacks by 36%, while heavy consumption of four or more cups causes a 64% increased risk of heart disease.
If people only under the age of 50 are considered, heavy coffee consumption in slow metabolisers elevates the risk of heart attacks fourfold compared to those consuming less than one cup per day. Among women, moderate or heavy caffeine intake is associated with a lower fertility rate and higher risk of pregnancy loss.
Therefore, caffeine doesn’t have a universally medicinal or detrimental effect – the reaction is entirely dependant on your genes. If you are a slow metaboliser then caffeine could be detrimental to your health, if you are fast metaboliser than moderate caffeine will possibly be protective against certain diseases, such as heart disease, and a perfect pre-training supplement for better focus and a lowered perceived rate of exertion.
1. Genome-wide association analysis of coffee drinking suggests association with CYP1A1/CYP1A2 and NRCAM. Molecular Psychiatry (2012) 17, 1116–1129; doi:10.1038/mp.2011.101
2. Gongora-Alfaro JL. [Caffeine as a preventive drug for Parkinson’s disease: epidemiologic evidence and experimental support] La cafeina como un farmaco preventivo de la enfermedad de Parkinson: evidencias epidemiologicas y sustrato experimental. Rev Neurol 2010; 50: 221–229.
3. van Dieren S, Uiterwaal CS, van der Schouw YT, van der AD, Boer JM, Spijkerman A et al. Coffee and tea consumption and risk of type 2 diabetes. Diabetologia 2009; 52: 2561–2569.
4. Krul C, Hageman G. Analysis of urinary caffeine metabolites to assess biotransformation enzyme activities by reversed-phase high-performance liquid chromatography. J Chromatogr B Biomed Sci Appl 1998; 709: 27–34.
5. Crews HM, Olivier L, Wilson LA. Urinary biomarkers for assessing dietary exposure to caffeine. Food Addit Contam 2001; 18: 1075–1087.
6. Selbach O, Haas HL. Hypocretins: the timing of sleep and waking. Chronobiol Int 2006; 23: 63–70.
7. Higdon JV, Frei B. Coffee and health: a review of recent human research. Crit Rev Food Sci Nutr 2006; 46: 101–123.