Benefits and Dangers of a Low FODMAP Diet for Carbohydrate Intolerance and IBS

The low FODMAP diet is a dietary approach, designed to help manage the symptoms of Irritable Bowel Syndrome (IBS), other gastrointestinal disorders and carbohydrate intolerance. FODMAPs, which stand for Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols, are types of carbohydrates that can resist normal digestion and cause digestive issues in sensitive individuals.

This diet consists of three main phases: Elimination, Reintroduction, and Personalisation. Each phase plays a crucial role in identifying and managing food triggers to improve digestive health.

Phase 1 -  Elimination

Elimination is the first step in the low FODMAP diet. During this phase, individuals reduce their intake of high-FODMAP foods for a specified period of time, typically ranging from 2 to 6 weeks. The goal is to alleviate symptoms by minimising the intake of foods that are known to cause digestive distress. High-FODMAP foods, include some fruits, dairy products, wheat, legumes, onions, garlic, and specific sweeteners. This phase is crucial for assessing whether FODMAPs are the cause of an individual's symptoms.

Phase 2 -   Reintroduction

Once the Elimination Phase is complete and symptoms have improved, the Reintroduction Phase begins. This involves systematically reintroducing FODMAPs back into the diet, one at a time, to identify which FODMAPs trigger symptoms and determine individual tolerance levels. Each FODMAP subgroup should be reintroduced separately, while maintaining a low FODMAP background diet, to accurately assess reactions. This phase typically lasts 6 to 8 weeks and requires careful tracking of symptoms by keeping a food diary. The goal is to identify which FODMAP groups are tolerable and which should be limited or avoided.

Phase 3 -  Personalisation

The final phase is Personalisation, where individuals establish a long-term, sustainable diet based on their specific triggers and tolerances which were identified during phase two. This final phase allows for the reintroduction of foods that were well-tolerated, while continuing to avoid those that cause discomfort. The aim is to create a balanced diet that minimises symptoms while maximising food variety and enjoyment. It's important to note that FODMAP tolerance can change over time, so individuals are encouraged to periodically re-test foods that were previously not tolerated.

The Benefits of a Low FODMAP Diet

1. Symptom Relief for IBS and Small Intestinal Bacterial Overgrowth (SIBO) :

The keyword for low FODMAP is ‘symptoms’. It doesn’t solve what’s driving your IBS or SIBO, but it can temporarily switch off the negative experiences that accompany it.  Studies indicate, that up to 86% of people with IBS experience symptom relief, including reduced gas, bloating, diarrhoea, constipation, and stomach pain when following a low FODMAP diet.

Cutting out FODMAP foods will halt those experiences and give the sufferer some respite, resulting in:

2. Improvement in Quality of Life:

By alleviating gastrointestinal symptoms, the low FODMAP diet can improve the overall quality of life for people with IBS.

But - it’s not without its downsides.

FODMAPs are mainly carbohydrates, which means they are usually healthy, nutrient-dense foods that taste delicious and contain high amounts of nutrition, healthy gut microbes and other health-giving benefits. Long-term avoidance (over 6 weeks) can negatively impact your nutrient status over time, and eventually manifest as low mood, fatigue, brain fog and other systemic issues that are not immediately identifiable as gut or diet induced.

Nutrient Deficiencies Associated with Long-Term Adherence to a Low FODMAP Diet

1. Fibre Deficiency

Fibre is crucial for maintaining healthy digestion and regular bowel movements. This deficiency can result in constipation and other digestive issues. Although low FODMAP sources of fibre exist, such as certain fruits, vegetables, and grains, the overall intake may still be insufficient.

2. Calcium Deficiency

Calcium is essential for bone health and various metabolic functions. The exclusion of high-FODMAP dairy products can lead to decreased calcium intake, increasing the risk of bone-related issues over time, such as osteoporosis.

3. Iron Deficiency

Iron is vital for oxygen transport in our blood and DNA synthesis. This deficiency can lead to anaemia and associated symptoms like fatigue and weakness.

4. Vitamin B Deficiencies

Vitamins B1, B2, B6, B9, and B12 are critical for energy metabolism and neurological function. A low FODMAP diet can lead to deficiencies in these vitamins, especially if individuals restrict foods like whole grains, certain types of vegetables, and meat. Vitamin B12 deficiency is particularly concerning for those following a vegetarian or vegan version of the diet.

5. Magnesium Deficiency

Magnesium is important for our muscle and nerve function, as well as bone health. Many good sources of magnesium, such as beans and nuts, are often restricted during the initial phase of the low FODMAP diet, potentially leading to deficiency.

6. Zinc Deficiency

Zinc plays a role in immune function and wound healing. The low FODMAP diet can result in reduced zinc intake, particularly if individuals avoid foods like whole grains and certain types of meat.

7. Prebiotic Fibre Deficiency

Prebiotic fibres, such as oligosaccharides, are important for maintaining a healthy gut microbiota. The low FODMAP diet restricts these fibres, which can negatively impact our gut health by reducing beneficial bacteria. This alteration in gut microbiota can occur in as little as 3-4 weeks.

Other downsides to a long term FODMAP diet

2. Impact on Gut Microbiota: a long term low FODMAP diet may also reduce beneficial bacteria such as bifidobacteria, very important for abundant, healthy gut bacteria. This reduction could have long-term implications for gut health, necessitating careful monitoring and potential supplementation.
3. Complexity and Adherence: The low FODMAP diet can be complex to follow, which can cause anxiety. It requires careful planning and adherence which creates additional barriers to food and freedom.
4. It’s Temporary: This diet provides short-term, symptomatic relief and on returning to FODMAP foods may trigger a resurgence of IBS symptoms which can be frustrating. It doesn’t address the underlying drivers that led to IBS, or food sensitivity.
5. Potential Psychological Impact: The restrictive nature of a low FODMAP diet may contribute to stress or anxiety around food choices and this can exacerbate IBS symptoms.

IBS is multifactorial, avoidance is just one thing to do

IBS is a multifactorial condition that revolves around how the body processes a certain set of carbohydrates. In a fully functioning digestive system, digestive enzymes and probiotics work together to break down foods and the by-products of their fermentation, without any symptoms arising.

It’s often the case, that IBS is the downstream result of a course of antibiotics, food poisoning or other gut bug, essentially meaning that the road to IBS began with an episode of inflammation, which was not resolved at the time.

Inflammation in the digestive tract, no matter how mild, will affect our body’s production and activation of digestive enzymes and disrupt our gut’s natural, protective and anti-inflammatory microbiome.

If you are stuck, or struggling on a low FODMAP diet, consider adding a carbohydrate-focused digestive enzyme and an evidence-based, IBS-safe probiotic at the same time. You may find by combining supplementation with reintroduction –  you will get a better, long-term result, overall.