What is the low-FODMAP diet?
Fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAPs) are carbohydrates (sugars) which may be poorly absorbed in the small intestine. As a result, they move to the large intestine. Consequently, they are fermented by bacteria. The bacteria release gas, and some sugars pull in water. Thus, these FODMAPs can lead to the gut symptoms of Irritable Bowel Syndrome (IBS) – bloating, pain, gas and altered bowel habits.
The low-FODMAP diet is not meant to improve general health. In addition, it is not a diet for life. Rather, it is a treatment tool. It can help people with IBS identify which of the fermentable sugars affect them.
The low-FODMAP diet phases
Initially, the low-FODMAP diet begins with removal of all FODMAPs. This is called the elimination phase. This phase is followed by the challenge phase, in which each fermentable sugar is tested systematically. Finally, the reintroduction phase reduces the level of dietary restriction. It also increases prebiotic intake (a type of fibre that feeds our good bugs!). The final aim is to normalise the diet as much as possible.
A low-FODMAP diet may have a negative effect of health if these phases are not well implemented. Areas of health affected may include nutrition, microbiology and quality of life.
The effect on nutrition
Any diet that restricts multiple foods means a risk of nutrient deficiency. Furthermore, this is more likely if the diet excludes many nutritious foods. A low-FODMAP diet restricts various healthy foods across food groups; especially fruit, vegetables and wholegrains.
The main areas of concern include:
- Carbohydrates: Carbohydrate intake may be reduced. Due to this, fibre and B-vitamins may be at risk. This may also affect energy levels. Thus, ensuring inclusion of low-FODMAP grains (e.g. oats, rice, quinoa) is important.
- Calcium: There are concerns around low-FODMAPPERs not meeting Calcium needs (important for strong bones!). Include low-lactose dairy products or calcium fortified alternatives daily. Alternative milks must be fortified to at least 120mg/100ml calcium.
Luckily, the short-term impact on most nutrients seems minimal within a standard elimination phase (anywhere from 2-8 weeks). However, problems arise when individuals stay on the diet long-term.
The effect on the gut microbiome
Large dietary changes can have a big impact on the bacteria living in our gut (our gut microbiome). We rely on the peaceful relationship we have with our gut bacteria to keep us healthy. A healthy gut microbiome provides you with energy, promotes gut function, supports mental health and prevents disease.
Specifically, studies have shown a low-FODMAP diet reduces a type of healthy bacteria known as, ‘bifidobacteria.’ Additionally, other evidence suggests it might reduce quantity of other good bugs.
The action of this is at least partly due to the fact that the low-FODMAP diet restricts the fermentable sugars that many bacteria feed on. These carbohydrates help them to grow and multiply. Specifically, the ‘prebiotic’ fructans and galacto-oligosaccharides found in foods such as wheat and legumes are reduced.
The effect on Quality of Life
It is undeniable that undertaking a low-FODMAP diet is a challenge. While it may improve quality of life through symptom control, it can be difficult. There is a great deal of planning required, heavy food restriction and potentially social isolation too.
The bottom line:
The low-FODMAP diet can be an effective strategy to manage IBS. Management by a dietitian skilled in FODMAPs is essential to minimise negative effects on your health. The long-term goal is to find balance with minimal dietary restriction.
By: Ellie Wiltshire
Image sourced from pinterest.
– Barrett, J.S, ‘How to institute the low-FODMAP diet,’ Journal of Gastroenterology and Hepatology, vol. 32, no. 1.
– Staudacher, H.M, ‘Nutritional, microbiological and psychosocial implications of the low FODMAP diet,’ Journal of Gastroenterology and Hepatology, vol. 32, no. 1.