Special diet that restricts some carbs can relieve IBD symptoms within a month

Symptoms of inflammatory bowel disease (IBD) can be relieved through diet in the space of a month, a study has found for the first time.

King’s College London scientists tracked patients with Crohn’s disease or ulcerative colitis who were put on a ‘low FODMAP’ diet.

Volunteers were told to restrict certain carbohydrates, which include wheat, fruits high in sugar and various other foods. 

More than half of those studied saw a reduction in the severity of their symptoms after four weeks, such as bloating, diarrhoea and abdominal pain.  

Despite years of research, scientists have never discovered an effective diet for IBD patients – although some foods may trigger symptoms. These are managed with drugs or surgery.

Even during periods when the disease is in remission, and medication is controlling gut inflammation, symptoms can persist in every day life.

The King’s College London study offers fresh hope of a safe and cost-effective way of relieving the symptoms suffered by thousands. 

A diet low in carbohydrates could relieve symptoms of inflammatory bowel disease (IBD) in just a month, a study by King's College London has found for the first time

A diet low in carbohydrates could relieve symptoms of inflammatory bowel disease (IBD) in just a month, a study by King’s College London has found for the first time

Lead researcher Dr Selina Cox said: ‘We know that the low FODMAP diet is effective in patients with irritable bowel syndrome (IBS).

‘This is the first randomised, trial showing that it’s effective in reducing common gut symptoms. 

‘This improves health-related quality of life in patients with IBD when they are in remission.’

Inflammatory bowel diseases, such as Crohn’s disease and ulcerative colitis, involve chronic inflammation of the digestive tract.  

Fifty-two patients were used in the study. They all had persistent symptoms of IBD – despite their inflammation being under control with medication. 


Inflammatory bowel disease (IBD) is a medical term that describes a group of conditions in which the intestines become inflamed (red and swollen).

Two major types of IBD are Crohn’s disease and ulcerative colitis.

Ulcerative colitis affects the large intestine (colon) whereas Crohn’s disease can occur in any part of the intestines.

Symptoms may include:

  • Abdominal cramps and pain frequent
  • Watery diarrhoea (may be bloody)
  • Severe urgency to have a bowel movement
  • Fever during active stages of disease
  • Loss of appetite and weight loss
  • Tiredness and fatigue anaemia (due to blood loss) 

People of any age can get IBD, but it’s usually diagnosed between the ages of 15 and 40.

The conditions are chronic and cannot be cured so treatment usually relies on medication and lifestyle changes to manage the symptoms, but may include surgery.

IBD is thought to affect some three million people in the US, over 300,000 Britons, and 85,000 Australians.

Source: Crohn’s & Colitis Australia

The participants were divided into two groups, 25 followed a normal diet and 27 adopted a low FODMAP diet. 

FODMAPs – fermentable oligosaccharides, disaccharides, monosaccharides and polyols – are types of carbohydrates found in certain foods. 

Typically foods that contain wheat, such as cakes, biscuits, breads and white pasta, are banned on the restrictive diet. 

Dairy products are a no-go, as well as fruits and vegetables containing high fructose, such as apples, bananas and pears.

Of the group that followed a low FODMAP diet, 52 per cent reported adequate relief of gut symptoms after four weeks.

In contrast, just 16 per cent of the ‘normal’ diet group experienced the same benefit, according to the researchers. 

According to the paper published in the journal Gastroenterology, the low FODMAP group had a higher quality of life score, too. 

The researchers also took stool and blood samples at the beginning and end of the study to assess gut bacteria levels among the volunteers. 

They found patients on the low FODMAP diet had less of a certain gut bacteria called Bifidobacteria after four weeks.

The scientists said this was concerning because Bifidobacteria can be beneficial for people with IBD by reducing inflammation.

But despite the changes, gut inflammation did not appear to increase after the low FODMAP diet, results showed.

And, overall, the gut microbiome diversity and markers of inflammation did not differ significantly between the two groups. 

Commenting on the findings, Professor Kevin Whelan from King’s, said: ‘Indeed, this could represent a safe and cost-effective management option.’ 

IBD affects around 150,000 people in the UK – but is only becoming more common, according to the Royal College of General Practitioners. 

An estimated three million people in the US were diagnosed with IBD in 2015, according to the latest figures from CDC.

An estimated one in five people with ulcerative colitis have severe symptoms that don’t improve with medication, the NHS claims. 

And up to 75 per cent of people with Crohn’s will need surgery to repair damage to their digestive system. 

The team at King’s plan to study the long-term effects of a low FODMAP diet and see what happens if FODMAP foods are reintroduced to the diet. 

Dr Cox said: ‘In clinical practice, the low FODMAP diet is followed by a phase of gradual FODMAP reintroduction.

‘It is important to establish what the effects of FODMAP reintroduction are on the gut and whether reintroduction reverses the bacterial changes that were observed during the low FODMAP diet.’   

The charity Crohn’s and Colitis UK welcomed the findings, but warned FODMAP isn’t for everyone with IBD.

Nikul Bakshi, research programme lead, said: ‘FODMAP diet is very restrictive and also cuts out some types of food that may be helpful in managing the conditions. 

‘We would always recommend people get advice from a qualified dietician before making changes to their diet. 

‘We really welcome these findings because research into food and IBD is seriously lacking, and the relationship is still poorly understood. 

‘It’s good to see positive results, and if the FODMAP diet can help alleviate debilitating symptoms for some people with Crohn’s and Colitis, this is promising. 

‘This study is the first of its kind, but it is still relatively small, with only a one in two success rate.’


FODMAPs are types of carbohydrates found in certain foods, including wheat, beans, fruit and vegetables.

FODMAPs include fructose (when in excess of glucose), fructans, galacto-oligosaccharides (GOS), lactose and polyols (eg. sorbitol and mannitol).

Studies have shown strong links between FODMAPs and digestive symptoms like gas, bloating, stomach pain, diarrhea and constipation, therefore, it is seen as the most effective dietary therapy for irritable bowel syndrome (IBS).

The diet sounds restrictive, but there are still many foods that are allowed.

For example, white bread can be swapped for wheat bread or spelt sourdough bread.

Lactose is banned, but many cheeses, such as Brie, Camembert and mozzarella.

And although you cannot eat garlic, mushrooms or onions, it’s fine to eat broccoli, courgette and butternut squash. 

FODMAP is an acronym that stands for:

Fermentable – meaning they are broken down (fermented) by bacteria in the large bowel

Oligosaccharides – ‘oligo’ means ‘few’ and ‘saccharide’ means sugar. These molecules made up of individual sugars joined together in a chain

Disaccharides – ‘di’ means two. This is a double sugar molecule.

Monosaccharides – ‘mono’ means single. This is a single-sugar molecule.


Polyols – these are sugar alcohols (however don’t lead to intoxication)

Source: FODMAP Friendly