Sunday 24 March 2019

Is the FODMAP diet really all it's cracked up to be?

As the regime gains traction among IBS sufferers, Katie Byrne rounds up the experts and asks if the restrictive eating plan is always necessary

Legumes, are to be avoided on the low FODMAP diet
Legumes, are to be avoided on the low FODMAP diet
Certain salads and vegetables, as well as (left) legumes, are to be avoided on the low FODMAP diet

Nutritional advice was limited for those who presented with IBS 10 years ago. In most cases, they were told to eat more fibre, ditch the dairy and report back if there was no improvement.

Nowadays, gastroenterologists tend to work alongside dieticians, who themselves are taking a more targeted approach towards treating the syndrome.

Enter the low FODMAP diet - an evidence-based eating plan with an impressive success rate.

Developed by a research team at Monash University in Melbourne, Australia in 2005, the diet is proven to reduce or eliminate the symptoms of IBS in 70pc of patients.

FODMAP is an acronym that stands for fermentable (the process through which gut bacteria ferment undigested carbohydrate to produce gases); oligosaccharides (wheat, rye, onion, garlic, legumes, pulses); disaccharides (milk, soft cheeses, yogurt); monosaccarides (honey, apples, high fructose corn syrup) and polyols (found in some fruits and vegetables and used in artificial sweeteners).

In simpler terms, FODMAPs are short-chain carbohydrates (sugars) that aren't absorbed properly in the gut, and which researchers now believe trigger symptoms in people with IBS.

During the low FODMAP diet, the patient eliminates all of these food groups for a two to six-week period, under the guidance of a dietician. The dietician then gradually re-introduces certain food groups, which helps the patient identify, and eliminate, the foods that are causing trouble.

The high-restriction phase is challenging but there are plenty of alternatives. Garlic is out but it's OK to flavour food with garlic-infused oil. Likewise, onions are off the menu but chives and the green part of spring onion are allowed.

"IBS sufferers often try to guess their trigger foods," says dietician Lorraine Maher, co-author of Gut Feeling. "The low FODMAP diet takes the guesswork out of it."

Maher, who studied FODMAPs in King's College London, says the plan is "very effective".

"We see resolution of symptoms in 80 to 90pc of patients, which is a higher success rate than the literature," she says. "But maybe that's because of the comparatively small sample size."

The diet can be complicated to follow, she adds, and problems often arise when a patient embarks on the plan without supervision.

In some cases, they make mistakes. In other cases, they stay in the restriction phase long-term, risking nutritional deficiencies and jeopardising their gut health.

"If you don't do it properly, it's like trying to find a needle in a hay stack," she says.

Dietician Elaine McGowan, who has clinics in Dublin and Limerick, says all IBS sufferers would benefit from two sessions with a qualified dietician who specialises in the area of IBS, gastroenterology and FODMAPs.

She was one of the first Irish dieticians to implement FODMAPs and she has since treated thousands of patients with the plan.

"I look at their family history, their medical history and then I would look at their diet," she says. "Depending on what their symptoms are, I might only use a modified version of the FODMAPs plan."

Maher and McGowan don't prescribe the low FODMAP diet as a matter of course.

Maher tends to assess the patient's stress levels first, usually by asking what their symptoms are like when they're on holiday.

"If they say they don't have symptoms, it's because they are away from normal stress, and they can relax," she says. In this scenario, she reminds her patients that destressing the mind will, in turn, destress the gut.

McGowan likes to look at overall eating habits when she first meets with a patient. "What we are seeing in the last 10 years is excesses of certain food components," she says. "We have some people eating too much pasta and too much bread and too much pizza.

"They are just consuming too much and if you consume too much your tummy is going to bloat and you are going to get some flatus. Reduce the amount and you have fewer symptoms."

Then there are the patients eating 'superfoods' to excess: "People who decide to go vegan or vegetarian are massively increasing their consumption of fruits and vegetables and salads," explains McGowan, "and a byproduct of that is that they ferment gas. This produces bloating, wind and diarrhoea which, assuming there is no underlying medical condition, is quite normal if you eat a tonne of fruit or veg."

She adds that functional gut symptoms are on the rise amongst clean eaters. "People are increasing their intake of vegetables and salads that are high in antioxidants," she says, "but not everyone is able to process them."

Dieticians are also encountering many IBS sufferers who have self-diagnosed themselves as gluten-intolerant.

"They tell us that gluten-free products make them feel better, less bloated, and more energised, but studies show that fructans (a FODMAP found in wheat) are actually triggering the symptoms of IBS," says Maher.

"People get a positive response from gluten-free products but they are pinpointing the wrong part of the grain that causes them trouble."

McGowan agrees: "In many cases there is absolutely no need for a gluten-free diet unless there is a proper diagnosis of coeliac disease. In a very small percentage of the population - it's exceptionally small -some people have non-coeliac gluten intolerance. If these diagnoses are not there, then it could just mean that you are consuming too much wheat."

An elimination diet like the low FODMAP plan is not a first line of defence strategy for IBS sufferers, adds Maher.

First and foremost, she advises her patients to reduce their consumption of meat and to eat a diverse diet of plant-based foods like fruit, vegetables, nuts, seeds, lentils and chickpeas. "They should also eat several small meals a day rather than a few big portions and take the time to digest their food properly rather than gulp it down. If that doesn't work, then we might consider the low FODMAP plan."



Fructose: A simple sugar found in many fruits, vegetables and added sugars.

Lactose: A carbohydrate found in dairy products like milk.

Fructans: Found in many foods, including gluten grains like wheat, spelt, rye and barley.

Galactans: Found in large amounts in legumes.

Polyols: Sugar alcohols like xylitol, sorbitol, maltitol and mannitol. They are found in some fruits and vegetables, and often used as sweeteners.

These foods should be eliminated for a short period of time, under a dietician's supervision, and then slowly reintroduced

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