What Foods Cause Diarrhoea?

The foods you eat and the way you prepare them can either nourish or disrupt your normal digestive function.

Some foods contain certain ingredients that your gut might be sensitive to, which can cause diarrhoea or other symptoms of an upset stomach such as nausea, vomiting, or stomach ache. But everyone reacts to foods differently. You might be able to tolerate gluten, but it could trigger diarrhoea for another person.

Aside from being a symptom of food sensitivity, diarrhoea also occurs as an adverse side effect of a medication or because of an underlying condition. However, diet, especially when taken in excess, is often the culprit.

With that said, here are seven foods that may either cause or exacerbate diarrhoea.

1. Sugary foods

Do you often find yourself racing to the bathroom after eating a slice of cake? If you do, then you might be extra sensitive to the stimulating effects of sugar on your gut. When you eat a dessert, your stomach produces water and electrolytes to dilute the sugars in your food. The spike in your stomach’s water content can loosen bowel movements and lead to diarrhoea within 30 minutes after ingestion. You may also experience nausea, bloating, or stomach pain.

Cakes and candies are not the only offenders. Fructose, a type of sugar that is commonly found in fruits, salad dressings, sweetened yoghurt, juice drinks, and soda, can also cause diarrhoea. Based on research, 75% of people who eat around 40g to 80g of fructose each day will develop diarrhoea. For example, a medium-sized apple has about 10g of fructose. If you eat four of them in one day, you may experience some digestive problems.


If you have a sugar intolerance or Irritable Bowel Syndrome (IBS), you might have difficulty digesting FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols).

FODMAPs are foods that contain sugar alcohols and short-chain carbohydrates that draw fluid into your bowel, an osmotic effect that prompts them to move quicker than normal into your small intestine. They are also fermented rapidly by your gut bacteria, which leads to an increase in gas production. This increase in fluid and gas content can cause diarrhoea, bloating, excess wind, constipation, and abdominal pain.

Large amounts of FODMAPs are normally found in Jerusalem artichokes, garlic, wheat, asparagus, honey, apples, plums, mangoes, cherries, cashews, pistachios, garlic, onions, beans, chickpeas, lentils, rye, dairy products, and rum.

If you suspect that you have a sugar intolerance or IBS, and are not sure what foods to avoid, consult your dietitian.

3. Alcoholic beverages

Have you ever had diarrhoea after a night of binge drinking? When consumed heavily, alcoholic beverages can loosen bowel movements. Three of the main reasons are water overload, increased gut contractility, and gastritis.

  • Water overload. Similar to the stimulating effects of sugars, alcohol also forces your gut to release more water to dilute and flush it out, which unfortunately can be in the form of loose, watery stools.
  • Increased gastric motility or movement. Large amounts of alcohol may put your body into overdrive. This triggers the muscles around your colon to contract faster, thereby pushing waste through the intestines and into the rectum rapidly.
  • Gastritis. Liquor and spirits help increase acid production in your gut, which can irritate your intestinal lining, also known as gastritis. When this occurs, you will have diarrhoea, nausea, and abdominal pain as your symptoms. Worse still, you may also end up vomiting bile because of the irritation that alcohol causes to your gut and intestinal lining.

Additionally, people with gut illnesses, such as IBS, coeliac disease, ulcerative colitis, and Crohn’s disease are more at risk of developing diarrhoea from alcohol. These diseases may increase their gut’s sensitivity to alcohol, thereby amplifying their symptoms after drinking.

Since you’re losing a lot of water and electrolytes when diarrhoea occurs, you can get dehydrated. You must restore your body’s fluid and electrolyte balance by drinking more water and eating foods that are rich in potassium, calcium, magnesium, phosphate, chloride, and sodium, such as bananas, almonds, avocados, kale, and spinach. We also recommend avoiding alcoholic drinks or caffeine until you recover.

4. Fatty foods

When high-fat foods aren’t absorbed normally, they go to the colon, where they are converted into fatty acids. This causes the colon to release fluid into the bowel, thereby increasing fluid content and triggering diarrhoea.

There are many reasons why some people experience difficulty digesting high-fat foods. In IBS patients, even eating moderate amounts of fried foods can worsen their diarrhoea. As for people with chronic pancreatitis, they can’t absorb certain types of nutrients and lipids normally. Therefore, when they eat fatty foods, they experience fatty or oily diarrhoea.

Sometimes, going through a difficult time in life can ramp up your appetite for high-fat comfort foods (or even alcoholic drinks) to feel better. However, this increases gastric motility or contractions that can result in diarrhoea.

If you have a chronic gut illness or feel the urge to overeat, avoid foods that contain lots of unhealthy fats as much as possible. These include junk foods, processed meat, lard and cream, lamb, pork, and fatty beef.

If you’re undergoing a period of extreme stress, do some relaxation exercises such as meditation, yoga, or tai chi. It’s also best to seek out the support of your friends and family during this time to improve your mood and overall mental health.

5. Fibre-rich foods

Some foods have high fibre content that can make them difficult to digest and cause constipation or diarrhoea.

Fibre acts as a bulk-forming agent that draws water into your gut. Thus, if you eat excessive amounts of fibre but have inadequate water in your digestive system, dehydration of the gastrointestinal tract can occur. This results in hardening and difficulty passing stools or constipation. This is common when the fibre you consume is soluble fibre, which is present in beans, apples, blueberries, strawberries, or oatmeal.

Conversely, loose, watery stools can occur when you suddenly introduce large amounts of insoluble fibre into your system. This increases gastric motility, thereby propelling waste through your colon more rapidly than usual. Insoluble fibre is commonly found in corn bran, leafy greens, wheat, tomatoes, and broccoli.

Fibre still plays an important role in keeping our gut healthy so it’s not advisable to eliminate it from your diet. Instead, you might want to consider keeping your fibre intake at the minimum or eating low-fibre foods like bananas, applesauce, white rice, carrots, summer squash, and cold/hot cereals.

Adult men and women are encouraged to consume 38g and 25g of fibre each day, respectively. Meanwhile, the minimum daily fibre intake for children and teenagers vary by age:

  • Children 1 to 3 years old – 19g
  • Children 4 to 8 years old – 25g
  • Children 9 to 13 years old – 31g (male), 26g (female)
  • Teenagers 14 to 18 years old – 38g (male), 26g (female)

6. Lactose

Cow’s milk, cream, fresh cheese, and other dairy products are known triggers for diarrhoea, especially for those with lactose intolerance. If you have lactose intolerance, consider taking lactase enzyme supplements or replacing milk and dairy foods with lactose-free alternatives.

7. Gluten

Gluten is the protein in rye, wheat, and barley. Some individuals who have difficulty digesting gluten suffer from a chronic gut illness, such as coeliac disease. When you have this condition, your immune system reacts to gluten and inadvertently causes damage to your small intestine.

Even healthy individuals who have a sensitivity to foods that contain gluten may have diarrhoea, abdominal pain, or nausea after ingestion. If you suspect that gluten is the culprit behind your loose bowel movement, see your physician for a proper diagnosis before shifting into a gluten-free diet.

Keep Diarrhoea at Bay

Diarrhoea can be caused by certain types of foods and drinks. You can try to identify your trigger foods by keeping a food journal where you can write down the foods you eat daily, including when you eat them, how much of these foods you eat and how they affect you after digestion. Moreover, how you prepare your foods may also contribute to the development of diarrhoea.

If your diarrhoea is caused by a chronic gut disease or medication, talk to your dietitian or nutritionist to help you handle your symptoms better. They can also help you come up with a personalised meal plan that meets your daily nutrient requirements while reducing your chances of diarrhoea.

Need Our Help?

Book an appointment with an accredited dietitian or nutritionist by phone on (07) 3071-7405 between 8am and 6pm Monday to Friday or send us an enquiry. Alternatively, check out our Gut and Bowel Health services.