The FODMAP diet: Fructans
The FODMAP diet is an elimination diet of 4 groups of fermentable carbohydrates. During the diet, you’re supposed to eliminate oligosaccharides (fructans and GOS), disaccharides (Lactose), monosaccharides (fructose), and polyols (sorbitol and mannitol) from your diet for a short period of time. After that, you will reintroduce the FODMAP groups one-by-one to identify the group(s) that trigger your Irritable Bowel Syndrome (IBS) symptoms! One of the bigger and more complicated groups is the oligosaccharides, and mostly the fructans. This group contains a wide array of products and a lot of my clients find it hard to navigate this. So let’s dive deeper into the fructans!
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One of the big groups to eliminate during the FODMAP diet are the Fermentable Oligosaccharides. These are long-chain carbohydrates. This group is split up between FOS/fructans and GOS/galactooligosaccharides.
As mentioned above, there is a wide array of products in this group, like wheat, legumes, garlic, nuts, seeds, onion, fruits, and vegetables. You might start to wonder by now, ‘Will there be anything left to eat?’. Don’t worry, there will be, you just have to be a little bit careful with your food choices.
If you are looking for a comprehensive list of foods you can and can’t eat during the FODMAP diet, take a look at the Monash Unversity FODMAP app this really is the best food list you can use.
When you’re still a bit overwhelmed, don’t hesitate to schedule a free IBS symptom assessment with me.
The fermentable oligosaccharides are essential for a healthy gut microbiome. A lower intake of fermentable carbohydrates, in general, will lead to reduced diversity and health in the gut. The fermentable carbohydrates are broken down by our gut microbiome, and this will keep them well fed. Click here to read more about that.
In general, the FODMAP diet can bring relief of bloating, diarrhea, gassiness, pain, and constipation and any symptoms that are caused by IBS. Any of the FODMAP groups can worsen IBS symptoms IF you’re intolerant to the group. This is different for everyone and takes a personalized approach.
One of the symptoms that seem to be mostly fructan-based, is constipation. A little side note, I’ve seen this with many clients in my dietitian practice, but never found scientific evidence to support this. When clients come into my dietitian practice with mostly constipation, and sometimes bloating, an elimination of the fructan group in combination with adjustments in lifestyle and eating habits can already go a long way without having to do the full FODMAP diet!
For a low fructan elimination diet, it is very important to know exactly what to pay attention to. The FODMAP fructans are ‘hidden’ in many foods and will easily sneak into your diet. That’s why I’ll tell you exactly what to look out for!
Most gluten-containing grains also contain fructans, but not all! A low FODMAP diet doesn’t have to be gluten-free. And not all gluten-free products are low FODMAP (just to make it more complicated…)
Grains that contain fructans are (among others) wheat, spelt, rye, amaranth, barley, burghal, kamut, emmer, oats, lupin, freekeh. It can depend on the product if there is also a reasonable low fructan portion you could use. To check this, I’d recommend consulting the Monash FODMAP app!
If you want to use some high FODMAP grains in your diet (I would recommend this!) try sourdough bread. The sourdough preparation breaks down some fructans and creates a lower fructan bread! Click here to read more about sourdough.
Fruit and Vegetables
Fruit and vegetables are a more difficult group on the low FODMAP diet, it can be very hard to guess whether or not a fruit contains any FODMAPs or fructans. In order to do a proper elimination of fructans, always consult the Monash University FODMAP app or any other reliable list.
Examples of high fructan vegetables are: artichoke, asparagus, beetroot, broccoli, brussels sprouts, cabbage, fennel, leek, mange tout, button mushrooms, spring onion.
There is a special place for garlic and onion. Since many people seem to react more strongly to these 2 products and they also contain very high amounts of fructans. Identifying garlic and onion in prepacked products may not always be easy, not every product label mentions them clearly and sometimes the only thing you can find is ‘spices’. Be careful when you see this, and stay clear of the product.
Examples of high fructan fruits are: dried apricots, banana (ripe), blueberries, cantaloupe, dried cranberries, dates, dried figs, dried goji berries, grapefruit, honeydew melon, nectarines, persimmon, pomegranate, prunes, raspberries.
As you might have noticed, a lot of the high fructan fruits are dried fruits. Their fresh counterparts have lower amounts of fructans. This can be explained by the fact that the water content of fresh fruit is much higher (so you get less actual fruit per 100 grams) and because the carbohydrates can change during the ripening of the fruit.
Nuts and seeds
If you pay attention to the allowed portion sizes of the nuts and seeds, quite a lot is possible during a low FODMAP and low fructan diet. Click here to read my article about nuts and seeds.
Most nuts contain a combination of fructans and GOS, so be extra careful if you’re also intolerant to GOS!
Nuts and seeds that are high in fructans are: cashews, pistachio.
Beans and legumes
The main FODMAP content in beans and legumes is GOS. But some types do also contain fructans when you consume larger portions of the product. Here, it is also important to pay extra attention if you know you’re intolerant to GOS and fructans.
Beans and legumes that contain fructans are: baked beans, mung beans, kidney beans, black beans, lima beans, pinto beans, soya beans, split peas.
You may not expect it, but some drinks also contain FODMAPs and fructans. FODMAPs are water soluble, so if you soak high FODMAP products long enough, their FODMAP content will lower and diffuse into the water. This water, in turn, will be high FODMAP. Be mindful of this.
Drinks that are high in fructans are: aloe drink, coconut water, strong black tea, strong chai, chamomile tea, dandelion tea, fennel tea.
Unfortunately, I won’t ever be able to give you a conclusive list of products to eat and to avoid. New products are continuously being tested for FODMAPs and new insights sometimes come to the surface on previous tested products.
There are some other less known products I wanted to bring to your attention. ‘Hidden’ sources of fructans that may easily be overlooked.
When you’re checking ingredient labels for fructans these are some extra names to look out for: inulin (especially in gluten-free products), lupine flour, spices, chicory root (also in plant-based coffee!), FOS.
If you’re considering the FODMAP diet, but your main symptom is constipation it could be worth it to start with an elimination of fructans in combination with adjustments in lifestyle and eating habits.
High FODMAP (and fructan) products can be hard to guess. Always use a reliable list to decide on which products you can and can’t eat. If you have the means, I’d always recommend working with a specialized dietitian. The FODMAP diet is not easy and this can make it a whole lot more comprehensible! Click here to schedule a free symptom assessment.
Have you tried the FODMAP diet? Or only a part of it? Let me know in the comments below!
Hi there, I’m Manon.
In my daily life I work as a registered dietitian in the Netherlands with a special interest in gut health.
During my workday I get loads of questions about healthy food, recipes and lifestyle to make it a little easier to get healthy. On Positive Gut I collect my best recommendations, tips and recipes to make your healthy lifestyle a little easier!