The low-FODMAP (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) diet has attracted attention for managing functional gut orders like IBS, for which medical approaches are limited. However, as it is highly restrictive and encompasses a wide variety of foods, many people find it difficult to implement and adhere to.
The Michigan Medicine researchers say their modified version – which was outlined in two studies, both published in Clinical Gastroenterology and Hepatology – is easier to follow than the low-FODMAP diet and is just as effective.
“It’s frustrating for us as clinicians to say, ‘Here, just cut out all these things, and you'll be fine,’” said Dr Shanti Eswaran, lead author of the first paper.
“No one wants to live like that. So, we looked at whether or not we really need to take out everything that's in the diet. Or if, for some people, they can get away with a modified version of this restriction plan.”
The low-FODMAP diet: An approach for managing IBS
IBS, a common functional gut disorder with symptoms including abdominal pain, cramping, bloating, and changes in bowel habit, affects 11.2% of individuals worldwide. Often comorbid with conditions like depression and anxiety, it has a significant impact on quality of life.
The low-FODMAP diet, developed by researchers at Australia’s Monash University in 2005, has been shown to help three in four people with IBS manage their symptoms. This is thought to be because FODMAPs are poorly absorbed in the small intestine, so they pass to the large intestine, where gut bacteria rapidly ferment them into short-chain fatty acids and gases.
It is a three-step elimination programme that restricts consumption of all high-FODMAP foods, before gradually reintroducing them to see which ones trigger symptoms.
Examples of high-FODMAP foods include dairy- or wheat-based products; beans and lentils; and certain vegetables and fruits, such as artichokes, asparagus, onions, garlic, apples, cherries, pears, and peaches.
Patients react to two FODMAP foods on average
In the first study, participants started on the traditional low-FODMAP restriction diet, before various foods were reintroduced blindly to their diets. On average, patients reacted to two FODMAPs.
The results also suggested that individual FODMAPs might cause symptoms, rather than all of them together – but the most significant finding was that fructans and galacto-oligosaccharides (GOS) were most likely to worsen symptoms like abdominal pain and bloating.
Fructans are commonly found in onions, garlic, and wheat, while GOS is found in legumes and cruciferous vegetables.
“That led to the second study, in which an alternative ‘FODMAP-simple’ diet was developed and implemented,” said Dr William Chey, chief of the Division of Gastroenterology and Hepatology at Michigan and an author on both studies.
The simplified diet – which only restricts fructans and GOS without restricting polyols, lactose, or fructose – led to similar symptom reductions as the low-FODMAP approach, the team found.
Costly, restrictive, and difficult to stick to
There are multiple benefits to simplifying the traditional low-FODMAP approach, according to the researchers. Not only does it prohibit consumption of a wide variety of food groups, but the restriction period can lead to weight loss and deficiencies in nutrients such as iron and calcium.
What’s more, it is expensive.
“Cost becomes an issue, because the more exclusion you have to do, the more substitutes you'd have to purchase,” said Dr Prashant Singh, lead author of the second paper.
“Let’s say you are somebody who eats green beans, beans, and chickpeas, and now you must substitute all of that. Or you're substituting in gluten-free bread or lactose-free milk, which is more expensive than lactose-containing milk. All of those costs add up very quickly.”
While the researchers agreed that more research is necessary before recommending the approach to patients, they are encouraged that these early results could herald changes that may one day improve the lives of people with IBS.
“Fewer people dropped out of the FODMAP-simple diet compared to the traditional low-FODMAP diet, because it was less restrictive and you're less likely to lose weight on it,” added Singh. “We think FODMAP-simple has real potential of changing how we practise this diet in future.”
