The FODMAP diet is everywhere, but researchers warn it's not for weight loss
Low FODMAP foods, but quantity matters
by Dr Jane Varney, Department of Gastroenterology, Monash University, reproduced from The Conversation
The FODMAP diet is used to help manage
irritable bowel syndrome (IBS), but it’s becoming more popular. Now
bloggers and so-called health gurus have jumped on board, claiming it
can treat everything from acne to weight loss.
While it would be great if the diet did help to manage these
hard-to-treat conditions, these claims are closer to science fiction
than science.
What are FODMAPs?
FODMAPs are a group of carbohydrates
found naturally in a wide range of foods, including garlic, onion,
dairy, many fruits and vegetables, breads, cereals, pulses, nuts and
many manufactured foods.
FODMAP is an acronym that stands for Fermentable Oligo- Di-
Monosacharides And Polyols. Our team at Monash University coined the
term in 2005 when we showed
this group of carbohydrates trigger symptoms of IBS in susceptible
people, and reducing all of them together would have a greater impact on
IBS symptom relief than reducing any one of them alone.
Foods containing FODMAPs can trigger IBS symptoms in susceptible people.Shutterstock
How do FODMAPs lead to IBS?
FODMAPs attract water as they pass slowly
through the small intestine. They then pass undigested into the large
intestine where bacteria ferment them. In people with IBS, this leads to
excessive gas production and changes in bowel habit, along with many other typical IBS symptoms including pain, bloating and distension.
While a limited number of studies indicate weight loss is an unintended consequence
of a low FODMAP diet, the diet is ill fit for this purpose. For people
needing to lose weight, the food restrictions the FODMAP diet imposes
are unnecessary.
Unless carefully implemented, the diet can compromise intake of nutrients such as fibre, iron and calcium. This can lead to a shortage of these nutrients if the diet is followed strictly long-term.
One example of this is the diet restricts intake of prebiotics, the fuel source for good bacteria in our bowel. Numerous studies have shown
an unintended consequence of the FODMAP diet is it changes the
composition of the gut microbiota. While the long-term consequences of
these changes are unknown, it is not advisable to restrict FODMAPs
unnecessarily.
There is no scientific evidence to suggest the FODMAP diet reduces acne.
While weight loss may be an
unintended consequence of the FODMAP diet, strictly following the diet
long-term could lead to a shortage of important nutrients.Shutterstock
How should the FODMAP diet be used?
A FODMAP diet is a three-step diet best followed under the guidance of an experienced dietitian.
People follow the diet strictly at the start, and relax and personalise the dietary restrictions over time. The aim is to strike a
balance between adequate symptom control and a minimally restrictive diet.
In step 1, people reduce intake of all FODMAP groups below a
threshold level. The aim of this step is to reduce IBS symptoms. If IBS
symptoms improve sufficiently, people progress to step 2.
In step 2, people undertake a series of “food challenges” to determine which FODMAPs they can tolerate.
In step 3, well-tolerated FODMAPs are brought back into the diet,
while poorly tolerated FODMAPs are restricted, but only to a level
necessary to control IBS symptoms.
The success of the FODMAP diet is due to its widespread uptake among patients with IBS. Backed by scientific evidence, the diet is recommended in various local and international clinical guidelines as a first-line IBS treatment.
As consumer demand for low FODMAP food choices grows, some companies
have started to adopt Monash University’s low FODMAP certification.
Brands like Vegemite, Kellogg’s USA, and Bakers Delight now offer low
FODMAP-certified products.
But with bloggers and “health gurus” promoting fad diets under the
FODMAP name, our research team is spending more time combating disinformation. This takes time away from our research and the support
we can offer IBS sufferers.
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