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How does caffeine (or any additional agents) act as a laxative when ingested? I'm interested in the metabolic/signaling pathway.

zeller
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  • As someone who has serious digestive issues,I can testify that coffee has far more strong of an effect on motility than water does. In fact, I have found that coffee works better than otc laxatives too,at least in my case, and much faster. I imagine there are a lot of ibs sufferers out there who don't realize this and wonder why they have such bad problems in the mornings –  Sep 02 '13 at 19:10
  • https://www.quora.com/What-happens-when-you-water-plants-with-coffee-or-tea – Constantthin Jan 10 '21 at 09:16

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Coffee does have an effect on the peristaltic movement in the bowel.

Coffee increases rectosigmoid motor activity within 4 min after ingestion in some people. Its effects on the colon are found to be comparable to those of a 1000 kCal meal. Since coffee contains no calories, and its effects on the gastrointestinal tract cannot be ascribed to its volume load, acidity or osmolality, it must have pharmacological effects. Caffeine cannot solely account for these gastrointestinal effects.

Effectively, decaf and regular coffee stimulate peristaltic movement in the colon as effectively as a meal does. Caffeine is not the active agent then, but some other compound in coffee.

Source: Boekema PJ, Samsom M, et al. Coffee and gastrointestinal function: facts and fiction. A review. Scand J Gastroenterol Suppl. 1999;230:35-9. PMID 10499460.

  • Thanks, I'll check the paper. Does it mention the candidate substances causing the effect instead of caffeine? – zeller Apr 04 '12 at 12:17
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    I don't know because I can't access the article myself. Work done at the same time, by another group found that caffeinated coffee was 23% stronger than decaf, implying that most of the effect is not derived from caffeine. The source (PMID: 9581985; Rao, Welcher, et al. Eur J Gastroenterol Hepatol. 1998 Feb;10(2):113-8.). –  Apr 04 '12 at 19:39
  • It is accepted that unless 500 mg of caffeine is consumed at once, it is equivalent to drinking water for hydration purposes. From this and the results of these two papers, I speculate that water accounts for ~40% of the effect, caffeine for a further ~20%, and the remaining ~40% is an unaccounted coffee effect. –  Apr 04 '12 at 19:45
  • @leonardo: the effect of water would very much depend on the coffee. A cup of Italian coffee and a cup of American coffee have extremely different volumes. – nico Apr 06 '12 at 16:34
  • Yes, this is true. For hydration purposes, coffee is as effective as tap water. The effect on gut motility is strongest with caffeinated coffee, then decaf, then water, with both coffee types equal to a 1000 kcal meal. I've speculated how much of the effect they are able to attribute to the individual components (caffeine, coffee, water) based on their experimental results. What you suggest nico is a comparison now of two kinds of coffee, of which they would expect the differences seen from an espresso vs cup of coffee. –  Apr 06 '12 at 17:07
  • To address your American coffee vs espresso comparison, based on these results the greatest variation would be a result of the water volumes and the other extracts from coffee (since caffeine content of 1 oz espresso is about equal to one 8-oz cup of coffee). –  Apr 06 '12 at 17:09
  • This is all voodoo. It's simply the volume of whatever you drink, the more the stronger effect. Try it yourself, it's my experience anyway. Reason: the internal pressure is increased by anything you eat or drink. Therefore, the same urge after eating. – R Stephan Sep 10 '12 at 07:34
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    @rwst I'm sorry but you are incorrect. That source directly concludes that coffee's effect "[...] cannot be ascribed to its volume load, acidity or osmolality, it must have pharmacological effects." While also finding that these effects are not solely the effect of caffeine. –  Nov 22 '12 at 22:56
  • Caffeine alone certainly does have increased motility effects, speaking personally as someone who has gut issues (Crohn's and irritable bowel) and has experimented on the effects of drinking coffee/espresso vs. various doses of OTC caffeine pills (NoDoz, for those in the US). Just drinking water alone does not affect my motility, while caffeine alone or drinks containing it do. – MattDMo Nov 23 '12 at 05:21
  • I have noticed that other stimulants (Ritalin, Adderal) also have laxative effects which supports the pharmacological explanation. I've long assumed that similar mechanisms cause motor tremors and increased peristalsis. – Slavatron Oct 20 '14 at 17:16
  • It's not valid to compare anecdotal (or real, for that matter) effects of those drugs you mention to a specific effect of caffeine just because they are broadly classed as stimulant drugs. Those two drugs all have distinct mechanisms of action to how they work. However, if they increase gut motility (e.g., peristalsis) then it may coincidentally also increase defecation. –  Oct 28 '14 at 01:22