The low FODMAP diet - what to eat, what to avoid, menus and sample recipes - BeKeto

FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides and polyols), or fermentable oligosaccharides, disaccharides, monosaccharides and polyols, are a group of foods that ferment easily, are poorly absorbed and increase osmotic pressure. A diet that restricts FODMAPs was developed by Australian researchers at Monash University as a therapy to alleviate symptoms of irritable bowel syndrome (IBS).

The hypothesis of FODMAP was first published in 2005 as a major cause of Crohn’s disease development [1]. The theory was based on the fact that the increased intake of FODMAPs, typical of the modern Western-type diet, and their subsequent rapid fermentation in the large intestine contributes to increased intestinal permeability (so-called leaky gut syndrome), resulting in the development of the disease in people with a genetic predisposition.

What are FODMAPs?

So let’s decipher whether FODMAPs are and where they can be found. FODMAPs are made up of five main components:

Fructose – is available in the diet as a free monosaccharide, as a component of disaccharides (including sucrose) and in a polymerised form in fructans. When fructose is consumed as sucrose or in similar amounts to glucose, fructose absorption is estimated to be 85 %. When the amount of fructose far exceeds that of glucose, the absorption of this sugar is impaired. Furthermore, approximately 30 % of the population is unable to absorb fructose in its free form [1].

Fructans – are a group of compounds containing fructose polymers with a glucose molecule at the end of the chain. Depending on the number of fructose molecules, we distinguish between oligosaccharides (2 – 10 molecules) and polysaccharides (> 10 molecules). Typical examples of fructans are fructooligosaccharides (FOS) and inulin, which are classified as prebiotics. The prebiotic effect is due to the fact that fructans are not digested in the small intestine and enter the large intestine intact [2]. There, they can feed the intestinal microbiota, which can benefit its development, but also contribute to increased gas production and bloating.

Lactose – a milk sugar that is only digested in the small intestine in the presence of the enzyme lactase. Deficiency of this enzyme occurs to varying degrees in different countries and ethnic groups. The deficiency of this enzyme is estimated, for example, at 2 % in Scandinavia, while in Asian countries it can exceed 90 % [1]. Importantly, the amount of lactase decreases with age, which can cause problems with lactase digestion in old age

Polyols – a.k.a. polyols with a sweet taste, which is why they are often used as less calorific sugar substitutes. Polyols include sorbitol, xylitol, mannitol and maltitol. Polyols occur naturally in fruit. They are poorly absorbed in the small intestine and are fermented very quickly.

Galacto-oligosaccharides (GOS) – are oligosaccharides consisting of galactose molecules terminated by glucose. As with FOS, the chain length of GOS can range from 2 to 8 molecules and GOS are also classified as prebiotic products. Humans do not produce the enzyme that allows the breakdown of GOS, namely α-galactosidase, which is produced by intestinal bacteria. Legumes are a rich source of GOS. The way to reduce the levels of GOS in legumes is to heat-treat them.

Products in which we find FODMAPs

Fructose:

Fructose-rich fruits, e.g. peaches, mangoes, apples, watermelon, cherries and pears
Products containing glucose-fructose syrup, e.g. sweets, sweetened yoghurts, canned fruit, processed foods
Sweeteners, e.g. sucralose and saccharin

Fructans:

Wheat and rice products
Products rich in inulin, such as Jerusalem artichoke and chicory
Onions
Garlic
Asparagus
Artichokes
Broccoli
Brussels sprouts
Beetroot

Lactose:

Cow’s milk
Dairy products including yoghurt, ice cream (not sorbets), some types of cheese such as mascarpone, ricotta, country cheese

Polyols:

Cauliflower,
Mushrooms
Sweeteners ending in -ol
Chewing gums
Fruits, e.g. pears, apples, plums, nactarines, watermelon and others

GOS:

Asparagus
Beetroot
Onions
Garlic
Leek
Wheat

Low fodmap diet – when to use?

Nowadays, we already know that FODMAP intolerance is more common than just inflammatory bowel disease. FODMAP intolerance or hypersensitivity is often found, and this diet is also recommended for people with small intestinal bacterial overgrowth (SIBO). Interestingly, a diet high in FODMAPs is a diet usually considered healthy – rich in whole grains, vegetables and fruit. Why are some people hypersensitive to FODMAPs and others not? This is due to the limited production of particular enzymes needed to digest particular dietary components. Knowing that we have a deficiency of the enzyme lactase, for example, it is possible to take it in the form of an oral preparation during a meal containing lactose.

Symptoms of FODMAP intolerance

The problem with FODMAPs is what lies behind the letter F in the acronym, which means fermentable. During fermentation, gases are produced, including hydrogen, carbon dioxide and methane, which accumulate in the gut. In addition, FODMAP has an osmotic effect, i.e. pulling water down in the cells surrounding the large intestine. Therefore, the faeces produced in the intestine are more diluted and the intestinal contents increase in volume. Consequently, typical symptoms of FODMAP intolerance include:

bloating
gas
discomfort
a feeling of overflowing
abdominal pains
constipation or diarrhoea

The low FODMAP diet – 3 phases

The FODMAP-restrictive diet is not about eliminating FODMAPs altogether, but about limiting the amount of products containing FODMAPs. The low-FODMAP diet consists of three phases [3]:

Phase 1 – reducing FODMAPs and replacing products with those containing much less of them. Lasts 2 – 6 weeks until symptoms resolve. If symptoms do not resolve, it means that maybe FODMAP is not the problem.
Phase 2 – reintroduction. The low-FODMAP diet is continued, but one FODMAP-rich product at a time is introduced and ‘tested’ for 3 days to see if it causes adverse symptoms. For each product, the portion size is also increased to determine the ‘tolerable dose’. This phase lasts between 8 and 12 weeks.
Phase 3 – personalisation. In this phase, products tolerated in phase 2 are introduced into the diet, while symptom-causing products are reduced to a tolerable amount. This diet is maintained. It is recommended to re-test from time to time whether the symptom-causing products continue to cause hypersensitivity.

Low FODMAP products

Fruit: raspberries, strawberries, citrus fruit (mandarins, oranges, lemons, limes) grapes, kiwi, passion fruit, banana (unripe)
Vegetables: potatoes, peppers, cabbage (except Italian cabbage), tomatoes, olives, lettuce
Mushrooms: oyster mushrooms, mun mushrooms, marinated mushrooms
Cereal products: buckwheat, millet, oat, quinoa, rice
Dairy products: lactose-free products, renneted cheeses (yellow, parmesan, brie, camembert, feta, mozzarella)
Legumes: tempeh, cooked lentils
Meat, fish, eggs
Nuts: walnuts, pecans, Brazil nuts, macadamia nuts
Herbs and spices (except those containing garlic and onions)
Fats
Sweeteners: sugar, glucose, maple syrup, stevia

Importantly, many foods can contain both high and low FODMAPs depending on ripeness or processing. For example, an unripe banana can be eaten, but the more ripe it is, the higher the FODMAP levels increase. Cooking in water can lower levels of FODMAPs, which are mostly water-soluble and permeate the broth. Fermentation can lower the levels of FOS and GOS, which are excellent nutrients for fermenting microorganisms [4].

Low fodmap diet – sample menus, recipes:

When starting a low FODMAP diet, the key is to plan meals that not only follow the dietary guidelines, but are also tasty and satisfying. We present a sample two-day menu to help you understand how you can incorporate the low FODMAP diet into your daily life. These examples of breakfasts, lunches and dinners are chosen to provide a variety of flavours and textures, while still adhering to the restrictions of the diet. From the freshness of avocado at breakfast to the richness of flavours at dinner, these meals are designed to show that a low FODMAP diet can not only be effective, but also pleasing to the palate.

Low FODMAP diet – Day 1 menu

Breakfast – slice of sourdough bread, half an avocado, fried egg
Lunch – baked salmon with tomatoes, brown rice, cucumber and lactose-free yoghurt misoise
Dinner – salad with chicken, iceberg lettuce, parmesan, olives and tomato with olive oil dressing

Low FODMAP diet – Menu Day 2

Breakfast – oatmeal on lactose-free milk with peanut butter, raspberries and cinnamon
Lunch – vegetable frittata with eggs, yam, courgette and parmesan cheese
Dinner – grilled beef steak with roast potatoes and cooked broccoli

Low FODMAP diet vs. ketogenic diet

FODMAPs are mostly carbohydrates, also eliminated in the ketogenic diet, so both types of diets eliminate cereal products, most fruits and starchy vegetables. However, the purpose of these diets is quite different and there are product groups that differentiate their effects. For example, dairy products, generally used in the ketogenic diet, can worsen intolerance symptoms. On the other hand, on a low-FODMAP diet, you can eat buckwheat and rice products, which will not maintain ketosis. A ketogenic diet can be balanced to limit FODMAPs if they cause intolerance. It is then a very eliminationist diet, so to avoid nutritional deficiencies it is better to consult a specialist nutritionist.

A ketogenic diet with reduced FODMAPs

A combination of a ketogenic diet and a low-FODMAP diet can be a good choice when, in addition to FODMAP intolerance, the aim of the diet is to lose weight or improve blood sugar control. This diet combines the principles of both diets, namely limiting carbohydrates and FODMAP-rich foods. Contrary to appearances, this diet contains a lot of allowed foods such as:

Meat – beef, chicken, turkey, pork, including bacon, lamb, duck
Fish – tuna, salmon, other oily fish, shellfish
Eggs
Cheeses – cheddar, gouda, feta, mozzarella, parmesan
Vegetables – spinach, cucumbers, red peppers, turnips, lettuce, celery, broccoli, tomatoes, courgettes and many more
Berry fruits
Avocados
Plant-based drinks – unsweetened almond drink, macadamia nut milk
Nuts and seeds – Brazil nuts, macadamia nuts, peanuts, pecans, pine nuts, walnuts, chia seeds, pumpkin seeds, flaxseeds

Risks of a reduced FODMAP ketogenic diet

It may not always be a good idea to combine a ketogenic and low-FODMAP diet. In IBS sufferers, an increase in fats, especially saturated fats, may exacerbate the occurrence of gastrointestinal symptoms. In addition, the risk of nutritional deficiencies may be increased by following two elimination diets simultaneously. To date, there are no scientific studies conducted on the safety of a reduced FODMAP ketogenic diet and the potential health benefits.

Summary

The low FODMAP diet appears to be an important tool in managing and alleviating the symptoms of irritable bowel syndrome and other digestive disorders. Its effectiveness, based on limiting the intake of specific carbohydrates that can cause digestive problems, has been confirmed in various studies. Through the appropriate elimination and reintroduction of products, this diet offers an individualised approach to each patient, enabling them to find a balanced diet that minimises intestinal discomfort.

However, it is important to note that the low FODMAP diet is not suitable for everyone. It requires careful planning and adherence, which often involves the need to consult a dietician or other specialist. Emphasising the role of the specialist in the introduction and monitoring of the diet is crucial to ensure that the diet is safe, balanced and tailored to each person’s individual needs.