Coffee: Good or Bad for You?
Coffee has been one of the most controversial beverages in the past couple of decades. You hear from the news that it is bad for you, then you turn around & then hear it is good for you. What gives?! Depending on what category you fall in, you may find your answer.
Genetic Lottery
How fast do you break down, aka metabolize, coffee?
The ability to metabolize the caffeine in coffee is associated with a modification in your genes known as a single nucleotide polymorphisms = SNP (“snip”). This SNP is rs762551 of the CYP1A2 gene.
Those who have a homozygous genotype (AA) tend to be fast caffeine metabolizers, meaning they can process caffeine through their body pretty quickly and can handle a few cups a day.
People who carry the C allele (AC/CC genotypes) have slower caffeine metabolism, meaning that caffeine isn’t easily broken down and continues to stay in the system, resulting in longer-lasting effects, thus 1 cup may be enough to keep them alert for most of the day.
In the European population, 69% have the A allele, and 31% have the C allele. In East Asians, 65% have A allele, and 35% have C alleles. Africans have 60% with the A allele and 40% with the C allele, and lastly, Americans have 71% with the A allele and 29% have the C allele (rs762551 RefSNP Report - DbSNP - NCBI, 2020). This population frequency is roughly the same with the global population averaging out to be 67% A allele and 33% C allele, meaning that most people can metabolize caffeine quickly.
What does this mean for me?
Nutrition professionals can promote the consumption of coffee to those who can process it rapidly with a clearer conscious, and fast metabolizers can enjoy their morning cupS of jo, especially since it was found that “habitual intake of 3 to 4 cups of coffee appears to be safe and is associated with the most robust beneficial effects” (O'Keefe et al., 2018).
For those who are slower coffee metabolizers, like me, we may want to reduce or exclude caffeine from coffee, teas, and energy drinks. Alternatives to coffee can come in the form of chicory coffee, lemon water, coconut water, adaptogenic teas, golden milk (turmeric), chai, and matcha - which can all provide you energy without the jitters, post-coffee crash, and headaches that may follow. It can also help with weight management, especially if minimal milk and sugar are involved.
Why does coffee make you poop?
3 theories:
1) caffeine stimulates muscle contractions in your gut
2) irritation of the digestive tract may cause increased stomach acid and muscle contractions or spasms
3) increased hormones (e.g. gastrin and cholecystokinin) leading to greater stimulation of digestion and bowel movements
Caffeine may not be working alone!
While older studies claimed that caffeine was the main driver for gut stimulation, I took a deeper look into the literature and found that caffeine may play just one part in the story of gastric motor function! These older studies would often compare coffee to water, with results that showed a 50% increase in intestinal contractions, which led to the popular belief that coffee stimulates colonic motor activity.
Newer research shows that “since (unsweetened) coffee contains no calories, and its effects on the gastrointestinal tract cannot be justified by its volume load, acidity, or osmolality, it was soon recognized that it must have pharmacological effects. Thus, these findings were interpreted as being mediated indirectly by a component of coffee other than caffeine, which, by acting on epithelial receptors in the stomach or small bowel, would trigger a gastrocolic response, speculated at that time to be due to the release of cholecystokinin or another hormone such as exorphins, gastrin, or motilin, as well as the fact that other active ingredients contained in coffee could add their own direct effects on the gut’s smooth muscle" (Iriondo-DeHond et al., 2021).
In plain English: While caffeine can be one contributor to causing bowel movement, it could also be due to other hormones like CCK (a hormone that helps you feel full), exorphins (opioid-like molecule - maybe this is why coffee makes some people so happy/high/addicted!), gastrin (helps digestion), motilin (encourages food to move through your stomach and small intestine).
Is coffee is good for digestion? Yes & No. It depends.
It was found that coffee promotes the desire to defecate (a fancy word for poop) in at least 1/3 of the population, predominantly women, and is associated with an increase in rectosigmoid motor activity (aka the last portion of your intestines) … this increased activity occurred as soon as 4 minutes after drinking the coffee, caffeinated or not, but not after drinking hot water.
Coffee for Constipation
If you’re feeling clogged up, you’ll need foods that help your gut motility (the ability to cause muscles in your gut to push food from one end of your GI tract to other). Aside from upping your intake of fiber with water, coffee may be of benefit to you because it is full of chlorogenic acid, which stimulates gastrin, a hormone that is secreted from your stomach lining that aids in digestion by increasing stomach acid levels to help you break down food. Higher levels of acid can irritate your gut lining and stimulate your gut muscles to contract (kinda like when someone tickles you and then you start squirming, contorting, and twisting your body, but imagine your GI tract doing this), which then pushes the food forward, a process known as peristalsis.
Coffee and Diarrhea
On the other hand, imagine taking a laxative while you’re already dealing with diarrhea - it’s a terrible idea. While coffee may initiate digestion for some, it may cause some people’s bowels to go into overdrive and shove all their food out in one fell swoop! In doing so, the food moves through your GI tract way too fast, preventing nutrient absorption and loss of water. Make sure you drink water soon after and sprinkle in some electrolytes like lemon juice (vitamin C), a pinch of salt (Na, Cl), baking soda (phosphorus), and optionally some natural sugar to replenish all that you lost.
Regardless of whether you are a fast/slow metabolizer, if the coffee causes more harm than good by overstimulating and irritating your gut lining, it could result in exacerbation of anxiety, stress, and depression, and indicate that there may be an imbalance in the gut-brain axis. Working on the communication between your gut and brain by removing triggers, finding the root cause, and healing from the inside are your next steps.
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Iriondo-DeHond, A., Uranga, J. A., Del Castillo, M. D., & Abalo, R. (2020). Effects of Coffee and Its Components on the Gastrointestinal Tract and the Brain-Gut Axis. Nutrients, 13(1), 88. https://doi.org/10.3390/nu13010088
O'Keefe, J. H., DiNicolantonio, J. J., & Lavie, C. J. (2018). Coffee for Cardioprotection and Longevity. Progress in cardiovascular diseases, 61(1), 38–42. https://doi.org/10.1016/j.pcad.2018.02.002
rs762551 RefSNP Report - dbSNP – NCBI. (2020). National Center for Biotechnology Information. https://www.ncbi.nlm.nih.gov/snp/rs762551#frequency_tab
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