15 Foods High in Fructans: A Comprehensive Guide

Navigating dietary restrictions can be challenging, especially when it comes to understanding specific carbohydrates like fructans. These fermentable carbs are often the culprits behind digestive discomfort for many people, particularly those with irritable bowel syndrome (IBS) or following a low FODMAP diet. Whether you're trying to identify trigger foods or simply becoming more aware of what you eat, knowing which foods contain high levels of fructans is essential.

Fructans are chains of fructose molecules that humans cannot fully digest because we lack the necessary enzymes. Instead, these compounds ferment in our large intestine, potentially causing gas, bloating, and other digestive symptoms in sensitive individuals. While problematic for some, fructans also act as prebiotics that support beneficial gut bacteria for others.

What Exactly Are Fructans?

Fructans are a type of carbohydrate composed of fructose molecules linked together in chains with a glucose molecule at one end. Unlike simple sugars that are easily absorbed in the small intestine, fructans pass through to the large intestine where gut bacteria ferment them, producing gas and short-chain fatty acids.

The most common type of fructan is inulin, which is often added to foods as a prebiotic fiber. While beneficial for gut health in many people, those with certain digestive conditions may experience uncomfortable symptoms when consuming fructan-rich foods.

Structurally, fructans are classified by their chain length, with shorter chains known as fructooligosaccharides (FOS) and longer chains called inulin. The degree of polymerization—essentially the number of fructose units in the chain—can range from just a few molecules to several hundred, affecting how quickly they ferment in the gut and potentially influencing symptom severity in sensitive individuals. This structural diversity explains why some people may tolerate certain fructan sources better than others, despite similar total fructan content.

Why Fructans Matter in Your Diet

For most people, fructans are beneficial dietary components that promote gut health by feeding beneficial bacteria. However, for those with IBS, SIBO (small intestinal bacterial overgrowth), or fructan sensitivity, these compounds can trigger significant digestive distress. Understanding which foods contain high levels of fructans allows for better management of symptoms through dietary modifications.

The low FODMAP diet, which temporarily restricts fermentable carbohydrates including fructans, has shown effectiveness in managing IBS symptoms for approximately 75% of patients. Identifying personal triggers through elimination and reintroduction phases helps create a sustainable, balanced diet that minimizes discomfort while maintaining nutritional adequacy.

Common fructan-rich foods include wheat products (bread, pasta, cereals), onions, garlic, artichokes, chicory root, and certain fruits like watermelon and nectarines. The fructan content can vary significantly based on ripeness, cooking methods, and processing techniques. For example, cooking onions doesn't eliminate their fructan content but may change how concentrated they are in the final dish. Garlic-infused oil, interestingly, provides flavor without the problematic fructans, as these compounds are water-soluble but not fat-soluble—making it a valuable culinary workaround for those with sensitivities who still crave that distinctive flavor profile.

Grain-Based Foods High in Fructans

Many common grains and grain-based products contain significant amounts of fructans, making them potential triggers for sensitive individuals. Here are some of the most notable fructan-rich grain foods to be aware of:

Wheat and Wheat Products

Wheat is perhaps the most ubiquitous source of fructans in the Western diet. Products like bread, pasta, couscous, crackers, and breakfast cereals all contain varying levels of fructans. Interestingly, the fructan content in wheat products is often misattributed to gluten sensitivity, when fructans may actually be causing the digestive distress.

The processing method affects fructan content, with sourdough fermentation partially breaking down these compounds. This explains why some people who cannot tolerate regular bread may be able to enjoy traditional sourdough without issues. Additionally, wheat bran contains particularly high concentrations of fructans compared to other parts of the wheat kernel.

Rye and Barley

Rye contains even higher levels of fructans than wheat, making rye bread and crackers particularly problematic for sensitive individuals. Barley, used in beer production and as an ingredient in many soups and stews, also contains significant amounts of these fermentable carbohydrates.

Vegetables High in Fructans

The plant kingdom offers numerous vegetables rich in fructans. While nutritious for most people, these vegetables can trigger symptoms in those with fructan sensitivity:

Onions and Garlic

Onions and garlic are among the most concentrated sources of fructans in the vegetable world. Unfortunately for those with sensitivities, these aromatics form the flavor base for countless recipes across global cuisines. Even small amounts can trigger symptoms in sensitive individuals.

The fructan content in onions and garlic is water-soluble, meaning that the compounds leach into cooking liquids. This explains why garlic or onion-infused oils (where the solids are removed) are often tolerated by those following low FODMAP diets, as the fructans remain in the discarded solids while the flavor compounds dissolve in the oil.

Artichokes and Asparagus

Globe artichokes contain particularly high levels of inulin, a type of fructan. Jerusalem artichokes (sunchokes) are even more concentrated sources, earning them a reputation for causing significant gas and bloating even in those without specific sensitivities. Asparagus also contains notable amounts of fructans, particularly in the stalks.

Other Fructan-Rich Vegetables

Several other vegetables contain moderate to high amounts of fructans, including leeks (essentially concentrated onions), chicory root (often used as a coffee substitute or fiber additive), dandelion greens, and to a lesser extent, brussels sprouts, cabbage, and broccoli. The fructan content in these vegetables can vary based on growing conditions, maturity at harvest, and cooking methods.

Fruits Containing Fructans

While fruits are more commonly associated with fructose, several fruits also contain significant amounts of fructans:

Watermelon and Nectarines

Watermelon contains moderate levels of fructans alongside its high water content. Nectarines also contain notable amounts, particularly when fully ripened. The combination of fructans with free fructose in these fruits can be particularly challenging for those with multiple FODMAP sensitivities.

Portion size matters significantly with these fruits. While small servings may be tolerated, larger portions can lead to symptom accumulation as the fructan load increases.

Dried Fruits

The dehydration process concentrates all components in fruit, including fructans. Dried fruits like dates, figs, and prunes contain particularly high levels and should be approached with caution by those with known sensitivities. Even a few pieces can provide a substantial fructan load.

Legumes With High Fructan Content

Legumes are nutritional powerhouses but also contain various fermentable carbohydrates including fructans:

Chickpeas and Lentils

Chickpeas (garbanzo beans) contain significant amounts of fructans, making hummus and chickpea-based dishes potential triggers. Lentils also contain moderate levels, though the amount varies by variety, with red lentils typically containing less than green or brown varieties.

Cooking methods can impact the digestibility of these legumes. Thorough soaking, rinsing, and cooking helps reduce some of the fermentable components, though the fructan content remains significant. Sprouting legumes before cooking may also reduce fructan levels for some varieties.

Nuts and Seeds With Fructans

Several nuts and seeds contain notable amounts of fructans, though portion size is particularly important in this category:

Pistachios and Cashews

Pistachios contain the highest fructan levels among commonly consumed nuts. Cashews also contain moderate amounts, particularly when consumed in larger portions. Other nuts like almonds and hazelnuts contain lower levels and are often better tolerated in reasonable portions.

The processing method matters with nuts as well. Roasting may alter the carbohydrate profile slightly, while nut butters concentrate the components, potentially making symptoms more likely with smaller portions.

Additives and Processed Foods With Fructans

Modern food processing has introduced additional sources of fructans into our diets, often in unexpected places:

Inulin and Chicory Root Fiber

Food manufacturers frequently add inulin and chicory root fiber to products to increase fiber content or replace fat while maintaining texture. These ingredients appear in protein bars, yogurts, ice creams, and even supplements marketed for digestive health. Ironically, these "healthy" additions can trigger significant symptoms in sensitive individuals.

Label reading becomes crucial for those avoiding fructans, as these additives may appear under various names including inulin, chicory root extract, fructooligosaccharides (FOS), or simply "prebiotic fiber." Products advertising high fiber content or digestive benefits often contain these fructan-rich additives.

Managing Fructans in Your Diet

If you suspect fructans are causing digestive issues, there are several approaches to managing your intake:

Elimination and Reintroduction

The most systematic approach involves temporarily eliminating high-fructan foods, then methodically reintroducing them one at a time to identify personal tolerance thresholds. This process, ideally guided by a registered dietitian, helps pinpoint specific triggers while ensuring nutritional needs are met.

Many people discover they can tolerate small amounts of fructan-containing foods or specific types of fructans without symptoms. This individualized approach prevents unnecessary dietary restriction while effectively managing symptoms.

Enzyme Supplements

Some enzyme supplements containing alpha-galactosidase may help break down certain fermentable carbohydrates, potentially reducing symptoms. However, research on their effectiveness specifically for fructans remains limited. These supplements work better for some FODMAP groups than others and should be viewed as an occasional aid rather than a solution for regular consumption of trigger foods.

Conclusion

Understanding which foods contain high levels of fructans empowers those with sensitivities to make informed dietary choices. While this list highlights 15 common sources, it's worth remembering that individual tolerance varies significantly. What causes severe symptoms in one person may be perfectly tolerable for another.

For those with confirmed fructan sensitivity, working with a healthcare professional to develop a balanced, nutritionally complete diet that minimizes symptoms is the ideal approach. With careful attention to food choices and portion sizes, most people can find a sustainable eating pattern that supports both digestive comfort and overall health.