What is FODMAP stacking?
Just when you thought you had this FODMAP thing covered – you’ve downloaded the Monash app, you’ve emptied your cupboards and started the elimination phase and you’ve even got a few low-FODMAP meals under your belt (literally) - you see a post about stacking and you wonder ‘what’s this new thing I have to worry about?’.
In this blog we explain the term stacking. Why it’s likely not a problem for you, but if it is, how you can avoid it.
Like many things in life, success with the FODMAP diet can be all about timing and enjoying things in moderation.
FODMAPs
First, a quick reminder about FODMAPs. The FODMAP family is made up fermentable short chain carbohydrates from the Oligosaccharides, Disaccharides, Monosaccharides and Polyols groups. They are present in varying amounts in foods as wide ranging as dairy, bread, legumes, fruit and vegetables.
They cause problems once they leave the stomach and move through the rest of your gut. Either as a result either of drawing excess water into the small intestine and/or through subsequent fermentation once they reach the large intestine. These processes produce painful bloating, gas, diarrhoea and/or constipation.
Reducing intake of FODMAPs can reduce symptoms of IBS and diverticulitis in many people with these conditions.
The low FODMAP diet has three stages
In the first stage (the elimination phase) the aim is to remove all foods rich in FODMAPs from the diet and stick to low FODMAP serves of other foods that contain some FODMAPs and see if symptoms reduce. This works for around 70% of IBS sufferers.
Subsequently, the food containing the different FODMAP groups can be reintroduced into the diet, to identify which FODMAPs trigger symptoms and what can be tolerated and at what amount.
Hopefully, some FODMAP foods can be reintroduced for the final personalised diet stage, so that you can enjoy a broad and varied diet long term.
How much is too much?
You’ll notice it is called the LOW FODMAP diet, not the NO FODMAP diet. A diet completely free of fodmaps would be miserable, far too restrictive for good health and luckily is also unnecessary to control symptoms.
The Monash University team have worked out the amounts of each FODMAP consumed at a single sitting that would likely cause gut health symptoms. They’ve also determined that the effect is exacerbated if a food contains more than one type of FODMAP, but that an upper limit of 0.5g total FODMAPs (excluding lactose) per sitting is generally tolerable for people with IBS. The science doesn’t change, but the Monash team regularly re-checks the fodmap cut off points as new foods or new food varieties enter the market.
Traffic Light System
They have since tested hundreds of foods to set the cut-off level for low FODMAP serving sizes. They use a traffic light system to communicate the amount of each food that is low (green), moderate (orange) and high (red) in FODMAPs.
Only a very few foods are so high in FODMAPS that you need to avoid them completely in the elimination phase, these include onions; garlic; pears; honey; peaches; asparagus; fava, navy and red kidney beans; and wheat and rye based bread, pasta, breakfast cereals, cakes and biscuits.
Many other foods have no FODMAPs, only a trace of FODMAPs or have a reasonable sized low FODMAP serve, that you can include in all stages of the diet.
You can find this information in the Monash app.
Some examples
Ginger – has a single green dot next to its listing in the vegetables page. If you click on it , you will see that FODMAPs have not been detected in this food and it can be eaten freely.
Garlic - has a red dot next to its listing. It doesn’t have a reasonable green serving size – even a single clove contains sufficient fructans to take it over the low-FODMAP threshold.
Garlic shoots - There are smaller green serving sizes of garlic shoots even though they contains both fructans and fructose.
The Fodmap Friendly app presents the information differently. The app provides a PASS or FAIL for typical serves of different foods and the % of maximum low FODMAP serving size for each FODMAP. It also provides clear information on the maximum serving size that is classified low FODMAP.
What is stacking?
Stacking occurs when one or more of the different types of FODMAP in the constituent foods in the same meal (or in meals consumed close together) add up to more than the green cut-off point for that FODMAP.
Or together all the different FODMAPs add up to more than the green cut-off point of 0.5g for total FODMAPs.
In an afternoon snack of fruit and yoghurt with 1/3 ripe banana, 40g blueberries, 20g of raspberries, 50g of kiwi fruit and 200g of lactose-free yoghurt, all the fruit contain fructans.
Each fruit is at a low-FODMAP serving size, but together they add up to more than the cut-off point of 0.2g for fructans plus galacto-oligosaccharides.
It’s lactose-free yoghurt, but interestingly lactose isn’t generally considered for stacking anyway.
Now, before you get too worried, please note that this is unlikely to be a major problem for fodmappers. The Monash team have said that they were highly conservative in determining a low FODMAP serving size to allow people to include more than one serve of ‘green’ or low FODMAP foods at each sitting.
That’s why many dietitians recommend that you just consider foods in isolation and don’t worry about stacking… unless you are experiencing symptoms.
If you are in the elimination phase and experiencing occasional symptoms it could be because you are particularly sensitive to FODMAPs or you tend to prepare meals with a lot of different FODMAPs. In this case it may be worth thinking about ways to avoid stacking.
Our recipes avoid stacking
We have been extra careful when preparing all the recipes on our site. For example, if we have two ingredients in a recipe that have a low-FODMAP serving size, we have only included around half the maximum green serving size the two ingredients, to ensure that together they don’t tip the scales.
If you think that stacking is causing problems for you, you may wish to take a similar approach. We give you some more tips below.
Our Superflora Gut Health Shakes contain a mix of ingredients, but they have all been tested and certified low-FODMAP by Monash University at a 50g serving size.
We’ve also checked in with Monash to verify that our smoothie recipes containing 50g of Superflora, plus 250ml of milk and a low-FODMAP serve of fruit such as 1/3 ripe banana, 5 strawberries or a handful of raspberries are also low-FODMAP so you can enjoy with confidence.
Six tips to avoid stacking
1. Take the approach mentioned above and make good use of the Monash app. If you have two or more foods in the same meal with the same fodmap, reduce the maximum ‘green’ serving size of each down a little.
2. Dilute the FODMAPS. Try to include a good amount of the ‘green’ low-FODMAP foods in each meal – e.g., meat, poultry, fish, eggs, rice, oranges and carrots.
3. Be like Goldilocks and go for the middle-sized bowl. Stick to small to moderate portion sizes and eat regularly. If you wait a very long time between meals, you are more likely to be very hungry and consume larger servings and hence, more FODMAPs.
4. But do spread out your meals and snacks by 3 to 4 hours. It takes around 2 to 4 hours for the stomach to empty food into the small intestine (although it can be as quick as 40 minutes for a liquid meal). You want gaps between when the food containing FODMAPs reaches the large intestine and fermentation happens. If you let the stomach empty completely before eating, then you will also have a gap between when the different meals reach your large intestine.
5. If you can’t wait that long between meals and a snack - then stick with those foods in which there are extremely low or undetectable amounts of FODMAPs for your snacks. They can be identified in the Monash app as those foods with a single green dot next to them in their listing and wording such as ‘FODMAPs were not detected in this food’ or ‘Only trace amounts of FODMAPs were detected in this food’ in the app. Good examples are carrots, rice, oranges, and mandarins. Something like an orange and a glass of lactose free milk would work, or carrot sticks and a herb dip made with lactose-free yoghurt. Include more of the foods with some FODMAPs in your main meals (at green serving sizes) to ensure you are getting as much variety in your diet as possible.
Remember it will get easier if you make it through to the personalisation phase and have more food options. And ultimately - food freedom with minimal restrictions is the goal!
6. Fruits tend to be high in FODMAPs and can contain multiple FODMAPs. Try to have only one serve of fruit at a sitting and stick to the recommended 2 serves per day. Watch out for fruit combos in a fruit salad or smoothie. Combine fruits with different FODMAPs like strawberries (contain fructose) and raspberries (contain fructan) and a blackberry (contains sorbitol). Alternatively, combine mango (contains fructose) with kiwi fruit (contains fructan) and a clementine (fodmaps undetected). And keep to a single serving size of 1 cup of fruit overall at each sitting.
More on timing and motility
Understanding the inner workings of your gut including motility patterns can help with more than just avoiding stacking. Working with your body’s natural responses and patterns may help you to understand, manipulate or accommodate your symptoms.
Our guts all have a natural cycle of activity. There are cycles of quiet periods where the contents are gently moved backwards and forwards for mixing and then periods of more propulsive activity that propels the contents forwards along the length of the gut. This is known as the Migratory Motor Complex and tends to occur every couple of hours between meals. For some it coincides with a loud rumbling tummy and hunger. It acts as a housekeeping system that keeps everything moving through your digestive system. The duration of your natural cycle will be linked to whether you have long or short transit times through your gut. A short cycle will contribute to a short transit time, and vice versa.
IBS symptoms are largely connected to fermentation in the large intestine and hence typically occur 4 to 24 hours after eating a food rich in FODMAPs. If you have slower motility, it will take longer for the food to reach the large intestine and symptoms will occur later than in someone with faster motility.
Typically, those with IBS-D have faster motility and those with IBS-C have slower motility. This knowledge may help you to work backwards and identify a trigger food for you. However, we would always recommend working with a dietitian to systematically reintroduce foods and keep a dairy of symptoms.
Riding the waves
Food entering your stomach and then moving into the small intestine triggers much larger propulsive waves in the large intestine, which result in a strong urge ‘to go’, perhaps as soon as 15 minutes after eating. This is known as the gastrocolic reflex. This is enhanced when the food contains fats or oils. These strong propulsive waves in the colon also occur in the short period after waking.
If you have IBS, you may be able to use these natural patterns to your advantage. If you have IBS-C, ensuring breakfast is a good size and contains some healthy fats (full-dairy milk or some olive oil), may help with your morning movements.
Similarly, those with IBS-D may wish to eat small meals, reduce fat and oil content when eating out, and leave more time in the morning before leaving home to accommodate toilet visits.
These are things that you have probably worked out for yourself, but sometimes it is reassuring to know the science behind it.
Join in
Please join the conversation on our Facebook and Instagram channels and let us know your tips for avoiding stacking or working with your body’s natural rhythms.
We have just started a private Facebook group where you may be more comfortable sharing in a safe and supportive community. Please check it out and become part of our Friendly Fodmappers community. We can’t wait to get to know you!
Written by: Dr Mary Webberley, Chief Scientific Officer at Noisy Guts. Mary has a background in biology, with two degrees from the University of Cambridge and post-doctoral research experience. She spent several years undertaking research into the diagnosis of IBS and IBD. She was the winner of the 2018 CSIRO Breakout Female Scientist Award.