Struggling with Fructan Intolerance? Here’s What You Need to Know

What Exactly is Fructan Intolerance?

Fructans are carbohydrates that occur naturally in foods. They're composed of fructose units linked together by different types of bonds.

Fructan intolerance describes the inability to process or digest foods that contain fructans. Undigested fructan can lead to gastrointestinal symptoms like stomach bloating, gas, constipation, diarrhea and abdominal pain. While not a severe condition, fructan intolerance in very common in those with functional gut disorders, like Irritable Bowel Syndrome (IBS).

At the moment, there is no standardized test to diagnose fructan intolerance, though research is exploring the use of breath tests to identify those who may be fructan intolerant.

Why fructans cause digestive discomfort

Fructans are part of the 'O' category of FODMAP (Fermentable Oligosaccharides, Disaccharides, Monosaccharides And Polyols) carbohydrates, which the human body has limited ability to break down. In fact, only about 5–15% of fructans are absorbed in the small intestine.

Because the body cannot digest fructans, they instead travel through the gastrointestinal tract mostly intact. As a result, they draw water into the small and large intestine and are rapidly fermented by gut bacteria in the colon, producing gas. This extra water in the digestive tract and excess gas can lead to bloating, flatulence, cramping and other digestive symptoms.

Fructan intolerance vs. general food sensitivity

A food intolerance, like those to fructan, is different from a food sensitivity, though in practice the two terms are often used interchangeably. With food sensitivity, digestive symptoms occur following food intake but the cause or reason for the symptoms not fully understood.

For example, non celiac gluten sensitivity is a food sensitivity because the exact mechanisms triggering symptoms are unknown, while lactose intolerance and fructan intolerance are food intolerances because they are related to a lack of enzymes needed to digest lactose or fructan malabsorption and fermentation, respectively.

Both food intolerance and food sensitivity are different from immune or autoimmune reactions to food, such as with celiac disease or wheat allergy.

How to Spot Fructan Intolerance in Your Everyday Life

The first step in spotting fructan intolerance is linking digestive symptoms to consumption of fructans. Fructan containing foods generally trigger symptoms at least an hour and up to 12 hours after they are eaten, though the most common reaction window is 4-8 hours after a meal. This is because it takes time for the fructan-containing foods to pass through the digestive system.

Increasingly, fructans are recognized as one of the most common triggers among the 10 to 15% of US population with IBS. Although some healthy individuals experience symptoms related to fructans, symptoms can be especially pronounced among those with IBS or suspected IBS.

Common signs to watch out for

One of the most common signs of fructan intolerance is gas and bloating after meals that contain fructans, like wheat, certain fruits and vegetables and some types of beans and legumes.

Wheat, barley and rye all contain fructans so many who transition to a gluten free diet by eliminating gluten containing foods and notice symptom improvement are wise to suspect that they may be fructan intolerant. (note: if you can tolerate sourdough products made with wheat, rye and barley, this is a strong clude you may not in fact have a gluten intolerance and can rule out non celiac gluten sensitivity. More on this below.)

Because fructans are carbohydrates, they are not naturally present in fats or proteins (unless the fat or protein has been marinated or mixed with fructans). This means symptoms related to high-fat or protein-rich meals can be signs fructans are not the issue.

How fructan-rich foods trigger symptoms

All FODMAPs, including fructans, are poorly absorbed in the digestive tract and can induce symptoms via a number of mechanisms. Fructans draw water into the colon, creating abdominal distension and potentially diarrhea. They also undergo fermentation, which leads to gas and bloating. Researchers are also exploring potential immune-mediated pathways, which may be triggered in response to FODMAP intake.

Many with IBS also have visceral hypersensitivity and exhibit a heightened sensory response to physical symptoms, which can increase the perceived severity of digestive sensations.

Which Foods Contain Fructans?

Historical data from the USDA estimated that the average fructan consumption in the US was 3.91 g/day, but experts agree that consumption is likely significantly higher than this due to recent trends in the Western diet and increased reliance on processed food. The most common source of fructans in an average diet is wheat and wheat-based products, such as bread, breakfast cereals, pasta and couscous.

Following wheat, alliums like garlic, onion, shallot and scallion are top sources of fructan, along with many fruits and vegetables like asparagus, beets, Brussels sprouts, savoy cabbage, ripe bananas and artichoke. Beans and legumes, including kidney beans, navy beans, black beans, lima beans, some soy products, and certain nuts, like pistachio and cashew, are all also fructan sources.

Surprising high-fructan foods to look out for

A common source of hidden fructan in food is fiber added to processed foods. Check for fructan-containing ingredients like inulin or chicory root, which are added to foods like fiber or protein bars, powders and drinks to boost their fiber content.

When eating out, marinades, sauces and broths may also be a hidden source of foods high in fructans that would be overlooked at first glance of a menu. Ask whether garlic and onion are used in their preparation.

Easy swaps for low-fructan options

For those looking to follow a low fructans diet, garlic infused oils, low FODMAP spices and broths and fresh herbs can provide flavor in lieu of garlic and onion.

Traditional wheat-based sourdough bread can be enjoyed as an alternative to regular bread. This is because during the process of dough fermentation, bacteria reduce the fructan content in the wheat. However, a gluten free diet is not necessarily a low fructan diet. Know that many gluten free breads may still be high in fructans, especially if they contain fiber additives like inulin or chicory root.

Low fructan grains, like quinoa or brown rice, can also be great alternatives to wheat products.

Simple Steps to Manage Fructan Intolerance

Fructans can cause IBS symptoms when they're consumed beyond tolerances. So it's important to learn your personal tolerance level to fructans (and other high FODMAP foods!) through FODMAP challenges.

Practical tips for managing your diet

A diverse, balanced diet full of whole grains, a variety of minimally processed foods and plenty of fruits and vegetables is the first step on promoting digestive health. Learn common foods high in fructan and limit their portion size based on what you know you can tolerate.

At mealtime, make a habit of eating slowly and mindfully and keeping hydrated with water, all of which support healthy digestion.

Low-fructan recipes and meal ideas

Many delicious meals can be low fructan. A few ideas to try:

  • Omelette with zucchini, chives and fresh herbs
  • Sourdough toast with peanut butter and strawberries
  • Quinoa tabbouleh with scallion tops, tomato, cucumber, parsley, lemon juice and olive oil
  • Sushi bowl with smoked salmon and wasabi-lime mayo
  • Roast carrots with cumin, rosemary and olive oil

Can Fructans Be Part of a Low-FODMAP Diet?

For those following a low FODMAP diet, a reduction in fructans during the elimination phase and a series of fructan challenges during the reintroduction phase is the standard approach to learn personal fructan tolerance levels.

Fructans can and should be part of a balanced diet, especially since prebiotics like fructans provide important benefits for gut health and are found in many of the most nutritious foods.

How to balance fructans in a FODMAP-friendly way

It is entirely possible to enjoy high fructan foods even if you are sensitive to them. The key is knowing what your limits are and keeping your intake below those levels at each meal or snack. Some may be able to enjoy 1/2 clove of garlic without experiencing symptoms, while others may need to keep their portions to 1/4 clove.

Symptoms can also be managed by following general, healthy eating habits. Include fructans are part of balanced meals, ideally with a lean protein, healthy fat and various fiber sources to support overall tolerance. Eat slowly and mindfully, and take a brief walk after meals to support digestion.

Also know that the low FODMAP approach is a helpful tool to learn these tolerances, but it is not the right approach for everyone. There are some contraindications to the low FODMAP diet worth considering.

Get Relief with FODZYME

Limiting fructan intake to just your tolerance levels can be frustrating. Sometimes you'll want to have more than just 1/4 clove of garlic, or maybe you want to enjoy two fructan-rich foods in the same meal, like pasta and caramelized onions. This is where digestive enzymes, like FODZYME, can make life much easier (and tastier!).

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FODZYME works by breaking down FODMAPs into simple carbohydrates that are absorbed in the small intestine before they can cause symptoms, like abdominal bloating, gas, diarrhea, constipation and stomach pain.

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