In this article, we’ll take a look at:
● What fructans are and the foods they’re found in
● What is fructan intolerance
● Whether digestive enzymes can improve the symptoms of fructan-intolerance and IBS
● What steps you can take to manage fructan intolerance
● Why people often confuse fructan intolerance with gluten sensitivity
What are fructans?
Fructans are polymers (long chains) of fructose with a glucose molecule at the end. Fructans with a chain length of 2-9 units are called oligofructose (or fructooligosaccharides), while those with more than 10 units are known as inulins.
Together with galactans, fructans make the “O” in FODMAPs.
What is fructan intolerance?
Fructan intolerance occurs when the body has difficulty handling dietary fructans, and is common in IBS patients who are generally sensitive to FODMAP-rich foods.
Interestingly, no human can naturally break down dietary fructans. Our bodies contain digestive enzymes (mainly in the small intestine) that help it break large dietary molecules like fats, proteins, and carbohydrates into smaller molecules like fatty acids, amino acids, and glucose for better absorption.
In the case of fructans, we don’t have an enzyme to break it down. We can only absorb about 5-15% of the fructans contained in our diet. This is why they’re considered as prebiotic — the majority of fructans pass down undigested to the large intestine where they’re fermented by bacteria. This process increases the number of healthy bacteria in our colon and is thought to be beneficial for health.
Patients with IBS are thought to have very sensitive guts — small increases in gas or water content can translate into considerably uncomfortable symptoms like bloating, abdominal pain, a feeling of fullness, diarrhea, or constipation.
So in these patients, the gas that’s released during fructan fermentation leads to nasty symptoms. Additionally, all FODMAPs (including fructans) are osmotic, which means they pull water into the gut. This is another way fructans can trigger IBS symptoms.
What foods contain fructans?
Some of the more common foods that contain fructans include:
● Processed foods, where inulin is added to increase their fiber content
● Many other fruits and vegetables
For a more extensive and practical list of high-fructan foods, it’s best to consult a dietitian or a doctor.
Can digestive enzymes improve the symptoms of fructose intolerance and IBS?
If you have IBS and are specifically intolerant to fructans, digestive enzymes may not be able to help you. There are currently no products available to break fructans specifically.
Some sources claim that an enzyme called alpha-galactosidase (which is commercially available as a supplement) may help patients tolerate fructans (and galactans) better. However, alpha-galactosidase is designed to break down the sugar galactooligosaccharide (GOS), which is found in foods like soy milk (produced from soybeans), beans, cashews, pistachios, and green peas.
While alpha-galactosidase supplements may also have some effect on fructans, no studies have proved this and it’s hard to say whether they can help you manage fructose intolerance.
If you have IBS, chances are that you’re intolerant to a wide range of FODMAPs. In this case, a general supplement that works on all FODMAPs (like FODMAP Digestive Enzymes) may be useful as it reduces the delivery of all FODMAPs to the large intestine, reducing fermentation and the gas and water that are produced as a result of it.
Note: it’s easy to confuse fructose with fructans. The two are different entities, and while there’s no enzyme supplement available to break down fructans, fructose can be broken down using xylose isomerase supplements in patients who are intolerant to it.
How to manage fructan intolerance?
If you think you may have fructan intolerance, the best way to approach it is to consider an elimination diet. This is where you avoid fructans for 2-4 weeks and monitor your symptoms. If they improve, you likely have fructan intolerance.
Importantly, once your symptoms improve, you must always re-challenge the body with fructans. Start adding fructan-containing foods one at a time to catch the specific foods that trigger your symptoms.
The goal is not to avoid all fructans but only those fructan-containing foods that trigger your symptoms. Remember, fructans are beneficial for your body. Not only do they increase healthy bacteria in the gut and keep gut motility optimal, but they’ve also been linked to improved blood glucose and triglyceride levels. They may also have positive effects on the overall lipid metabolism and immune functioning.
If you decide to eliminate all fructans from your diet for good, you’ll miss out on all these health benefits and take on unnecessary hassle as fructans are found in a wide range of foods.
In the context of IBS, a low-FODMAP diet (where you follow the above procedure with all FODMAP-containing foods) is also an excellent option. If you decide to take digestive enzyme supplements, here are some principles to bear in mind:
● Enzyme supplements don’t work for every IBS patient
● Enzyme supplements are not stand-alone treatments for IBS — they work best as a component of a holistic approach
● It’s important to review a product with your doctor before investing in it — inadequate doses can render supplements ineffective
Fructan intolerance and gluten intolerance
Fructan intolerance and gluten intolerance are different conditions but people often mix the two because many foods contain both.
If you get symptoms after eating wheat, barley, rye, and spelt, you can have either of the two conditions because these foods are high in both fructans and gluten. It’s best to seek medical advice to differentiate between the two intolerances.
Fructans are long chains for fructose and can trigger uncomfortable abdominal symptoms, especially in IBS patients. There are no specific enzyme supplements that target fructans but if you have IBS, a general supplement that targets all FODMAPs can be beneficial.
Medically Reviewed by Onikepe Adegbola, MD PhD