How alcohol and caffeine affect digestion

Published December 5, 2014

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If you’re like most adults, caffeine is a part of your daily routine and helps wake you up and keep you going. But while caffeine certainly has its perks it can pose problems too. Excessive caffeine can have a negative impact on digestion, especially if you’re susceptible to digestive problems. Likewise, too much alcohol can also interfere with digestive processes.

The effects of caffeine on digestion

Drinking too much caffeine from coffee, tea or other caffeinated beverages can cause or worsen digestive symptoms in some people. Caffeine relaxes the lower oesophageal sphincter (LOS), which is a small band of muscle that sits between the oesphagus and the stomach. Normally the LOS closes the oesphagus off from the stomach, preventing food from travelling from the stomach back up into the oesphagus. Caffeine can cause the LOS to relax, which can allow food to travel backwards triggering indigestion and heartburn in some people.1

Due to its acidic nature, caffeine and coffee have also been shown to enhance the production of stomach acid secretions and cause irritation.2 In addition, caffeine‐containing drinks have laxativepotential. Coffee can overstimulate the gastrointestinal tract and produces a laxative effect in susceptible people, in as little as four minutes after drinking.3 Even modest doses of coffee and decaffeinated varieties can result in loose stools, which means that the caffeine content isn’t entirely responsible, there may be other substances contributing to this effect.2

How much is too much?

Some people are more sensitive to caffeine than others; subsequently caffeine tolerability will differ from person to person. Based on the unfavourable effects of caffeine on the digestive system, anyone suffering from a digestive problem should consider eliminating or at least cutting back on caffeine consumption, but it’s important to wean off slowly. Swap your coffee for green tea, which has lower caffeine content or try a coffee alternative such as a dandelion latte.

The effects of alcohol on digestion

Drinking excessive amounts of alcohol has adverse effects on digestion. Similar to caffeine, alcohol can weaken or loosen the LOS and contribute to symptoms of heartburn.1 Alcohol makes the stomach produce more acid than usual, which can lead to irritation and inflammation of the stomach lining.4 Drinking alcohol may also impair nutrient absorption by damaging the cells that line the stomach and intestines, and interfering with the transport of some nutrients from inside the bowel into the blood.5 Furthermore, an excess of alcohol can lead to diarrhoea.5

How much is too much?

When it comes to alcohol intake, it’s important to stick to the lower risk guidelines. It’s recommended that healthy men and women drink no more than two standard drinks on any day and no more than four standard drinks on a single occasion.6 To lessen the effects of alcohol on digestion, ensure you eat something beforehand and drink plenty of water. If you’re prone to stomach distress, it might be best to avoid drinking completely.


  1. Harvard Medical School, Gastroesophageal reflux disease (GERD), July 2010, URL access:
  2. Natural Standard, Caffeine, 2014,,‐herbssupplements/c/caffeine/professional.aspx#dosingToxicologyGeneral
  3. Rafetto M, Grumet T and French G, Effects of caffeine and coffee on Irritable bowel syndrome, crohn’s disease and colitis, 2004, URL access:
  4. Drink Aware, Is alcohol harming your stomach? October 2014, URL access:‐thefacts/health‐effects‐of‐alcohol/effects‐on‐the‐body/is‐alcohol‐harming‐your‐stomach/
  5. National Institute on Alcohol Abuse and Alcoholism, Alcohol and Nutrition, 2003, URL access:
  6. Department of Health, Reduce your risk: new national guidelines for alcohol consumption, URL access:‐adult

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