FODMAP Diet for IBS
Until fairly recently, the dietary treatment of irritable bowel syndrome (IBS) was pretty poor. The standard advice for years and years was to eat the kind of typical healthy diet that doctors recommended for everyone – lots of fruit and vegetables, plus high fiber cereals and carbohydrates. The trouble with this approach was that it was based on little actual evidence that this diet helped IBS; it was just assumed that a high-fiber diet would benefit everyone.
When researchers started to study the effects of these foods on IBS sufferers they found that not only did this kind of diet rarely soothe IBS symptoms, but in many people it made them worse.
One study in 1994 published in The Lancet found that a massive 55% of patients reported that bran made their symptoms worse, whereas only 11% said it improved things for them. A similar number of people (45%) said that fruit made them feel worse and 25% had problems with vegetables.
It was thought that the insoluble fiber in bran could be causing the problems, as the soluble kind tends to be better for IBS, but that did not explain why fruits and veggies were messing up our insides too. It was only when researchers started looking into how certain carbohydrates affected IBS that they developed the low FODMAP diet.
What is FODMAP?
If ever a diet needed a handy acronym, it is this one! But first, a little education. FODMAP stands for this almighty mouthful: fermentable oligosaccharides, disaccharides, monosaccharides and polyols. Let’s break that down a bit, as there are just two things you need to know to understand this diet.
Firstly, fermentation is a process where a substance – food in this instance – is broken down into smaller parts by bacteria, yeasts and micro-organisms. The gas that is produced during this process is what causes our bowel problems because it bloats the intestines and leads to excess wind and pain.
Secondly, oligosaccharides, disaccharides, monosaccharides and polyols are all forms of short chain carbohydrate (the sugars and starches that make up a large portion of most people’s diets). It includes breads, pasta, pizza, fructose in fruit and lactose in milk. The word saccharide refers to any sweet-tasting carbohydrate.
Monosaccharide means one carbohydrate unit and is the kind of carb found in honey and some fruit. Disaccharide means two carbohydrate units and can be found in the lactose in milk. Oligosaccharide means several carb units, which is found in wheat and rye.
Finally, the P in FODMAPs stands for polyols which are sugar alcohols, more commonly known as artificial sweeteners such as sorbitol, mannitol and xylitol. These polyols are also found naturally in some fruit and veggies.
The FODMAP Diet and IBS
All high-FODMAP foods are poorly absorbed in the small intestine. Because they are not being absorbed, they attract more water into the gut and this can lead to diarrhea (this is sometimes referred to as the osmotic load). If you combine this extra water with the fermentation and gas described above, you have a recipe for the intestinal disasters of IBS.
The low FODMAP diet was invented by researchers at Monash University in Melbourne, Australia so it comes with some excellent credentials and has been studied pretty extensively over the past few years.
Does a Low FODMAP Diet Help IBS?
The short answer is yes! A 2016 review of previously published studies found that this diet shows consistent benefits for a majority of patients, which is not something you often read in IBS studies because it can be a tough disorder to treat.
The review found that up to a massive 86% of patients said that their symptoms had improved overall. Improvements were found in the whole range of IBS symptoms: stomach pain, diarrhea, constipation, bloating and gas. They concluded that the evidence we have so far strongly supports the idea that the low FODMAP diet works for IBS.
The reviewers added that if the diet was to work, special dietitians should help patients stick strictly to the guidelines. (They also stressed that this is not a diet to be followed stringently forever, as eating this way long-term could mean you do not get enough nutrients and could alter the balance of bacteria in your gut, but we will get to that in a minute.)
An analysis of studies published in 2017 found similarly positive results. It concluded that the diet was superior to the typical dietary advice given to IBS sufferers (eat regular, moderately-sized meals, eat less fat, cut down on insoluble fiber and things like caffeine and beans/onions) and should be recommended as the first choice of diet.
The strongest evidence from studies is for the reduction of stomach pain and bloating. There is also more evidence that the diet helps diarrhea-predominant IBS sufferers more than those with constipation, but the pain and bloating that comes with constipation can often be helped by following the diet, so there are still improvements to be gained if you have IBS-C.
Those with constipation may have better results if they also keep an eye on their fiber intake as this can reduce on a low FODMAP diet. Fiber supplements, such as Citrucel and Metamucil, can help to ensure you are getting enough soluble fiber.
What Can You Eat on a Low FODMAP Diet?
Now that the science bit is out of the way, what can you eat? Here’s a basic list of some high and low FODMAP foods to start us off.
High FODMAP Foods (to Be Avoided)
- Bread, cakes, biscuits and any other food made from wheat, barley or rye.
- Cows’ milk (also sheep and goat milk).
- Apples, pears, plums, watermelon, blackberries, peaches, prunes, cherries, nectarines, ripe bananas, dates, grapefruit.
- Cauliflower, sweetcorn, onion, garlic, leek, mushrooms, artichokes, shallots, peas, kidney beans, black beans, navy beans.
- Honey, high fructose corn syrup.
- Artificial sweeteners like sorbitol, isomalt, xylitol, and mannitol.
- Cashew nuts, pistachios.
- Chamomile or fennel tea, rum.
Low FODMAP Foods (to Be Eaten in Moderation)
- Gluten-free bread and pasta.
- All kinds of meat and all kinds of fish (but not breaded meats or fish).
- Bananas, blueberries, rhubarb, lemon, mandarins, orange, grapes, melon, strawberries, kiwis, coconut.
- Potato, carrot, swede, parsnip, turnip, quinoa, green beans, cucumber, lettuce, tomato, celery, parsnip, radish, spinach.
- Sugar.
- Olive oil.
- Oats.
- Some cheeses only, including cheddar, brie, mozzarella, parmesan.
- Eggs.
- Rice and rice cakes.
- Tofu.
- Almonds (small serving), peanuts, walnuts, Brazil nuts, pumpkin seeds, chia seeds.
- Lactose-free dairy products
- Coffee, tea, cranberry juice, peppermint tea, the majority of wines and beers, water.
The first thing you have probably spotted from that list is that going low FODMAP means both an almost completely dairy-free and gluten-free diet, excluding everything made from wheat, rye and barley, so it is not something to be taken lightly.
Your life is made easier by the fact that gluten-free breads are allowed (these are often made from rice or corn flours) and there are no restrictions on meat or fish at all, so you will not have trouble getting enough protein. You can also eat lactose-free milk and yogurt, any milks made from the safe foods, such as almond or rice milk, plus a number of low-lactose cheeses, like cheddar.
Also, bear in mind that foods from the low FODMAP list should still be eaten in moderation only because although these foods are low in FODMAPs, they are not FODMAP-free.
One dietitian gives the example of rice cakes which are low in FODMAPs and are a recommended snack on this diet. However, while one or two rice cakes will be low FODMAP, if you eat four in one sitting, then you will cross over into the high FODMAP range just from the serving size. This makes the diet rather more complicated than a simple list of banned foods to avoid.
Low FODMAP Foods Are Becoming More Common
In recent years, food companies have spotted a marketing opportunity and started selling ranges that are specifically made to be low in FODMAPs. Fody Foods sell various snacks and sauces that may be useful, particularly the sauces, as store-bought sauces can often have dozens of ingredients that may or may not be safe.
Find External Resources
If you are thinking at this point that it all sounds far too difficult to follow, do not despair. More and more dietitians are becoming trained to help patients navigate the diet, and there are excellent online resources available too.
The Monash University FODMAP app uses a traffic light system to classify foods into green, orange and red categories, with green foods low in FODMAPs, orange foods medium and red foods being the highest FODMAP foods available. It also offers advice on the typical serving size for each food per meal, so you do not end up accidentally overdosing.
Watch Out for Outdated FOMAP Lists
I should mention a quick point about lists of low FODMAP foods, which is that any list you find on the internet might be wrong, or at the very least out-of-date. This is because the diet is still being researched and improved as I write this, so although it has been proven to work for many people it is still a work in progress. Each food is being individually tested in the Monash University laboratory and sometimes retested more specifically – ripe bananas were recently found to be higher in FODMAPs than unripe ones, for example.
So, there is no single, comprehensive list, and the scope of the diet can seem rather daunting. My advice is stick to the lists and resources at the end of this article, as they are from the leading FODMAP experts in the world, and find a dietician trained in the diet who can guide you through the whole process.
Working with a dietician has three distinct advantages: it is much safer than doing it alone, as you will not worry about nutritional deficiencies, it is much more likely to work if you are choosing the right foods and it is going to be far easier to stick to the diet if you have got a specialist giving you lots of lovely recipes and emotional support.
A 3-Stage Diet
Now, it is vital to point out that you should not simply avoid all of the high FODMAP foods for the rest of your life. In fact, if you tried to do just that you would be likely to end up with other problems because your body would not be getting the nutrients it needs. Instead, the FODMAP diet should be followed via three separate stages.
Stage 1: Restriction
This is where you try to cut right down on your FODMAP intake. Guidelines vary, but it is generally recommended that this first, strict stage of the diet should be followed for between four and eight weeks while carefully monitoring symptoms for improvements.
Stage 2: Reintroduction
If there has been no improvement in your symptoms after four to eight weeks then, with advice from your dietitian, you may decide to try a different diet, as FODMAPs may not be your problem.
If you have seen an improvement then stage two of the FODMAP diet is to gradually reintroduce the high FODMAP foods to see which particular foods cause you the most problems and measure what level of FODMAPs in your overall diet your gut can cope with.
Your dietician will advise on the best way to undergo stage three – you could either start gradually with some medium FODMAP foods, start trying high FODMAP foods straight away, or start with some of your favorite foods that you have missed.
This may depend on how difficult or easy your symptoms have been to deal with and how mentally strong you are feeling; the safest route is to start with the lower-FODMAP foods and work your way up.
Stage 3: Personalization
This is an ongoing process where you use the information gathered in stage two and continue to refine your eating habits to find the very best diet for you. This diet may not completely eliminate your symptoms, but it should hopefully give you much more control over the IBS while also making sure that you are not avoiding any foods unnecessarily.
This stage is vital because you need to balance the sensitivities of your IBS with your body’s nutritional needs. Any diet low in dairy could lead to a lack of calcium, which is important for the health of bones and teeth. Vitamin b12 may also be lacking.
It’s also important because there is some evidence that the diet can affect the balance of good and bad bacteria in the gut, what is known as the microbiome. You may have heard of good bugs like bifidobacteria because they are often found in probiotics, and they are vital for a properly working gut.
A few studies have shown that a very low FODMAP diet may reduce the number of good bacteria inside the gut, which is not ideal. It’s much better to find your tolerance level and search for the foods that particularly upset you as an individual than following a needlessly strict regime.
Finding A Dietician
Your doctor or gastroenterologist may refer you to a dietician, but if you would prefer to find one yourself, make sure you look for a registered dietician (RD) or registered dietician/nutritionist (RDN), not someone who just uses the term nutritionist. This is because anyone using the title dietitian is required to be registered with a professional body and will need to be professionally qualified.
However, in many states, pretty much anyone can call themselves a nutritionist, so it does not tell you anything about their credentials, and they might not have any formal training at all.
You can use the Academy of Nutrition and Dietetics “Find an expert" service to search for help near you, either by zip code or by area of expertise (click on “digestive disorders" to see the IBS specialists). A list of FODMAP dietitians is also available on the IBS Free website.
Quick FODMAP Tips
If you have decided to give the low FODMAP lifestyle a try then here are a few hints and tips to get you started.
- Don’t change everything at once. When you start the FODMAP diet for IBS, it may feel counter-productive to keep taking your medications or supplements. After all, you want to know whether this diet helps you, not the drugs. But if you make too many changes at once, you will not have a clue which one is helping you – plus you will not know which change to cut out immediately if your symptoms get worse.
- Keep an open mind if your symptoms improve. It may be that you are sensitive to FODMAPs, but it could be another aspect of the diet too. For example, you could have been sensitive to gluten instead, or maybe a diet lower in fiber has helped calm your diarrhea. Work with your dietician here to identify what is going on.
- Remember to monitor anything you eat and drink in the first stage of the diet. It’s easy to forget that anything we swallow could contain FODMAPs, but plenty of cough syrups and liquid painkillers have sorbitol in, and diet sodas are only low calorie because they are stuffed full of artificial sweeteners.