Coffee and IBS: Should You Quit Your Daily Cup?

What is IBS?

IBS is a chronic gastrointestinal condition with no one obvious cause. It is a common condition that affects up to 15% of people worldwide. As a ‘syndrome,’ IBS is a collection of symptoms that commonly occur together. These include: 

• Abdominal pain
• Bloating
• Gas
• Constipation or diarrhea
• Nausea

While some of these symptoms may also be experienced by those who do not have IBS, people diagnosed with irritable bowel syndrome will experience them more frequently and over a longer period of time.
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What is coffee?

Coffee is a beverage made of beans extracted from the coffee plant (Coffea arabica). Although caffeine is the most commonly discussed component of coffee, the beverage is complex and contains over one thousand different compounds. These include:

• Caffeine
• Antioxidants
• Oils

The preparation and processing of the coffee can influence the compounds in a particular cup of coffee, and in turn, the severity of IBS symptoms.

How does coffee affect the body?

Results from a questionnaire in Sweden suggested that two-thirds of IBS patients drink coffee; of those, 39% of IBS coffee-drinkers reported worsened gut symptoms, including diarrhea and stomach pain. However, while several studies indicate caffeine may worsen IBS symptoms, there is no direct evidence that manipulating (or reducing) caffeine can improve IBS symptom control.

Coffee exerts effects on the nervous, cardiovascular and digestive systems. Although we know how coffee affects the nervous system and cardiovascular system, it is less known how the digestive tract is affected by coffee. However, IBS gut symptoms are strongly linked to the gut-brain connection (the link between the digestive tract and the brain). So it’s understandable that coffee, which affects the nervous system, can also affect the gut.

Why does caffeine worsen IBS symptoms?

The main reason caffeine can worsen IBS symptoms in some people is because of the high caffeine content. Caffeine stimulates alertness and mental focus but can also have negative impacts on the gut. The effects of caffeine and other compounds in coffee on the digestive system include:

1. Speeding up the movement of our bowels

The caffeine in coffee increases motility, that is, how quickly food moves through your system and speeds-up your need to ‘go.’ This happens as coffee stimulates the nerves and hormone receptors in the gut. One study showed coffee can increase the need for a bowel movement within 4 minutes of consumption! This is especially troublesome for those with diarrhea-predominant IBS since motility is already faster than it should be. Coffee may therefore worsen symptoms in people with diarrhea-predominant IBS. 

For those with IBS-C, caffeine may be helpful to stimulate the movement of digestive material in the gut. However, this approach should be taken with caution, as too much caffeine can still lead to abdominal cramps, even in people with IBS-C. 

2. Increasing stomach acid production

Coffee contains compounds that can stimulate acid secretion in the gut, including caffeine and catechols (a toxic organic compound). These compounds may be responsible for heartburn and indigestion by increasing stomach acid secretion. However, cold brew coffee may be less acidic than hot brewed coffee.

3. Increasing the stress response

Caffeine is problematic for IBS sufferers who experience stress or anxiety since this tends to create a spasmodic effect on the gut, which may be worsened by caffeine. Caffeine can also increase heart rate and the stress response, causing further symptoms. Since stress is known to worsen IBS symptoms, caffeine may contribute to an IBS stress-symptom cycle. 

4. Coffee contains Salicylates

Coffee contains a type of chemical compound called salicylates, which occur naturally in many foods and also produced artificially in products like aspirin and toothpaste. Salicylates are not FODMAPs (carbohydrates that cause IBS symptoms) but can cause similar gut symptoms. A small proportion of people are sensitive to salicylates, and this may cause symptoms of IBS. If you are unsure, it is best to consult a doctor or dietitian.

Does coffee cause acid reflux?

Not only can coffee cause IBS symptoms, it may also worsen symptoms of acid reflux, sometimes known as heartburn. If you experience reflux, or a longer-term form called gastroesophageal reflux disease (GERD), it may be best to avoid coffee. Some studies have shown coffee worsens symptoms of GERD. However, a large meta-study concluded that there was no association between caffeine and GERD in most subgroups. More research is needed to confirm whether this link exists and, if so, if it's the caffeine or the bitter flavored compounds that cause reflux in some people.

Coffee and low FODMAP diet

FODMAP is an acronym for “fermentable oligo-, di-, mono-saccharides and polyols” - carbohydrates found in many fruits and vegetables known to worsen IBS symptoms. The low FODMAP diet is an elimination diet that has been shown to improve IBS symptoms. 

Coffee is considered low FODMAP, so you don’t have to remove it while on the diet if it is well tolerated. But certain types of coffee and how it is prepared can increase the FODMAP content. For example, instant coffee and ground coffee may differ in FODMAP content: 

• Instant coffee: Check the ingredients to ensure the coffee is made of 100% ground coffee beans. Some instant coffees contain chicory root, which is high in FODMAPs. 
• Ground coffee: Coffees prepared from 100% ground coffee beans are generally considered low FODMAP. 

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Should you have milk in your coffee?

If you take your coffee with milk, this may contribute to digestive symptoms. Cow’s milk contains lactose, which is a FODMAP that may contribute to gut problems. In small quantities, milk is usually tolerable to people with IBS, but you may wish to remove it from your diet if symptoms become severe.

Are there milk alternatives?

If you are worried about IBS symptoms from milk, you may wish to order a milk-free coffee such as an Americano or short or long black. Otherwise, many available milk substitutes do not include lactose, including soya, oat, and almond milk. Another suitable substitute is lactose-free milk, which is similar to regular milk. Lactose-free milk may taste sweeter, but it doesn’t contain added sugar. Lactose is a natural carbohydrate (sugar) molecule that is made up of two smaller sugar molecules, one of which is glucose; these are separated in lactose-free milk. Because of this, some people find they can taste the sweetness of glucose more strongly. 

Should I cut caffeine?

Before you decide to cut caffeine completely, remove it from your diet for a couple of weeks and then re-introduce it in a small portion. This will allow you to test your tolerance in a controlled manner. If the caffeine does not seem to trigger symptoms, you should be able to include it in your diet. 

If you decide to include coffee in your diet, keep your caffeine intake to around 400 mg per day or less. Coffee has a high amount of caffeine, but be aware that there are other sources of caffeine too in different foods and beverages. Below indicates the typical amount of caffeine in:

• Coffee: 100-150 mg
• Cold brew: 100-150 mg
• Decaf coffee: 2-5 mg
• Dark chocolate: 20 mg
• Black tea: 25-50 grams

If you need an energy boost and are concerned about caffeine intake with IBS, consider a small healthy snack, meditating, taking a cold shower, or going for a brisk walk instead.

What do doctors recommend?

Patients have traditionally been advised to reduce caffeine intake to improve IBS symptom control. Several clinical guidelines suggest that caffeine intake be restricted (but not necessarily removed) if IBS symptoms are suspected. However, caffeine may improve digestive symptoms in some people, so it is worth talking with your doctor about any symptom changes. 

The Wrap-Up

Coffee has many benefits for health and may promote productivity and alertness. However, some people with IBS find that coffee exacerbates their symptoms. People with diarrhea as their primary symptom of IBS are likely to experience worsening symptoms; however, those with constipation may find the effects of coffee to be beneficial. If you have IBS, you should limit your coffee intake to one to two cups per day. If symptoms are particularly severe, you may want to consider cutting out coffee altogether or asking your doctor for advice.

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