Foods With Fructans and GOS: A Complete Guide

Millions of people worldwide experience digestive discomfort from specific carbohydrates known as FODMAPs. This article provides a comprehensive guide detailing what foods have fructans and GOS, two of the primary oligosaccharides that can trigger symptoms in sensitive individuals.

Quick Summary

Fructans and GOS are types of fermentable carbohydrates called oligosaccharides found in many common foods. This guide explores the different food sources for each, from grains and vegetables to legumes and nuts, and provides key information for dietary management, especially for those with sensitive digestive systems like IBS. It also highlights the distinction between these two types of fiber and their impact on gut health.

Key Points

• Fructans and GOS are Oligosaccharides: They are two types of fermentable carbohydrates (FODMAPs) that humans cannot fully digest.

• Fructan Sources: Key foods include wheat, onions, garlic, artichokes, and ripe bananas.

• GOS Sources: Found mainly in legumes like beans, chickpeas, and lentils, as well as cashews and pistachios.

• Fermentation Causes Symptoms: In sensitive individuals, these fibers are fermented by gut bacteria, causing gas, bloating, and other IBS symptoms.

• Low-FODMAP Diet: Managing intake of these foods through a structured diet plan, often guided by a dietitian, is the most effective strategy.

• Reintroduction is Key: After an elimination phase, reintroducing fructans and GOS separately helps pinpoint specific trigger foods and tolerance levels.

• Benefits as Prebiotics: In non-sensitive people, these fibers act as prebiotics, feeding beneficial gut bacteria and supporting overall digestive health.

What Exactly Are Fructans and GOS?

Fructans and Galacto-oligosaccharides (GOS) are both types of oligosaccharides, a class of fermentable carbohydrates under the FODMAP umbrella. Humans naturally lack the enzymes needed to break down these complex sugar chains in the small intestine, leading them to travel to the large intestine for fermentation by gut bacteria. While this process is beneficial for gut health in most people, producing short-chain fatty acids that support the growth of "good" bacteria, it can cause significant digestive distress in individuals with sensitive guts, such as those with Irritable Bowel Syndrome (IBS). Symptoms often include gas, bloating, and abdominal pain.

Fructans are chains of fructose molecules, often with a glucose molecule at the end. They are commonly found in wheat, onions, and garlic. GOS are chains of galactose molecules with a glucose end, primarily found in legumes and beans.

Foods Containing High Levels of Fructans

Fructans are pervasive in many diets, appearing in a wide range of food groups. For those on a low-FODMAP diet, knowing these sources is crucial for symptom management.

Vegetables:

• Onions and Garlic: These are two of the most significant sources of fructans in many cuisines. This includes all forms, such as powders and salts.
• Artichokes: Both globe and Jerusalem artichokes contain high amounts.
• Leeks: The white bulb part is particularly high in fructans.
• Other Vegetables: Beets, Brussels sprouts, savoy cabbage, fennel, and asparagus all contain fructans, though serving sizes may affect impact.

Grains and Cereals:

• Wheat, Rye, and Barley: Many common products, including bread, pasta, and cereals, are major sources of fructans.
• Spelt and Couscous: These also contain significant levels.

Fruits:

• Ripe Bananas: As bananas ripen, their fructan content increases.
• Dried Fruits: Dried figs, dates, raisins, prunes, and apricots have concentrated levels.
• Watermelon, Nectarines, and Persimmons: These are also known high-fructan fruits.

Nuts and Legumes (Shared with GOS):

• Cashews and Pistachios: These are a significant source of both fructans and GOS.

Foods Containing High Levels of GOS

GOS are primarily found in legumes but also appear in some nuts and soy products. For effective management, it's important to distinguish these from fructan sources.

Legumes and Pulses:

• Beans: Baked beans, black beans, bortolotti beans, and kidney beans are notable sources.
• Chickpeas and Lentils: Both chickpeas and lentils contain GOS, though canned varieties may have lower levels if rinsed.
• Green Peas: This vegetable is a source of GOS.

Soy Products:

• Soy Milk (Made from whole soybeans): This is a primary GOS source.
• Silken Tofu: Contains GOS, whereas firm tofu has less.

Nuts:

• Cashews and Pistachios: As noted, these are high in both GOS and fructans.

Fructans vs. GOS: Key Differences and Management

While both fructans and GOS can cause similar symptoms in sensitive individuals, understanding their differences is vital for a targeted dietary approach. Since many people react to one but not the other, it is recommended to test tolerance for each group separately during a reintroduction phase.

Feature	Fructans	GOS (Galacto-oligosaccharides)
Carbohydrate Type	Chains of fructose sugars with a terminal glucose molecule.	Chains of galactose sugars with a terminal glucose molecule.
Primary Sources	Wheat, rye, barley, onions, garlic, artichokes, ripe bananas.	Legumes (beans, chickpeas, lentils), cashews, pistachios, some soy products.
Gut Impact	Fermented by gut bacteria, causing gas, bloating, and other IBS symptoms in sensitive individuals.	Also fermented by gut bacteria, leading to similar symptoms in those with intolerance.
Enzymatic Support	No widely available supplement effectively breaks down fructans.	Some enzyme products on the market claim to aid in the digestion of GOS.
Cross-Contamination	Often present in the same foods as gluten (e.g., wheat), leading to misattribution of symptoms.	Less overlap with gluten-containing grains, but common in many vegetarian protein sources.

How to Manage a Diet High in Fructans and GOS

For those needing to restrict these carbohydrates, a structured dietary plan is the most effective approach. The low-FODMAP diet, developed by Monash University, is the most well-researched method.

Practical Strategies

• Elimination Phase: Temporarily remove all high-FODMAP foods, including those high in fructans and GOS, for 2–6 weeks. This helps to reduce symptoms and establish a baseline.
• Reintroduction Phase: Systematically reintroduce one FODMAP group at a time to determine individual tolerance levels. This personalization is key, as not everyone reacts to all FODMAPs equally.
• Personalization: You may discover that you can tolerate certain foods or smaller portions of high-FODMAP items. For instance, the green parts of spring onions are low-FODMAP, while the white bulbs are not.
• Enzyme Supplements: While not a solution for everyone, some people find relief using enzyme products designed to help break down specific FODMAPs. This option should be explored with a healthcare professional.
• Consult a Dietitian: A registered dietitian can provide personalized guidance to navigate the low-FODMAP diet, ensuring nutritional needs are met while identifying trigger foods. This prevents unnecessary dietary restrictions and potential nutrient deficiencies.

Conclusion

Fructans and GOS are important types of fermentable carbohydrates found in a wide variety of healthy foods, including grains, vegetables, legumes, and nuts. While they serve as beneficial prebiotics for many, their fermentation in the gut can cause significant digestive issues for sensitive individuals, such as those with IBS. By identifying which foods have fructans and GOS and understanding their impact through a structured elimination and reintroduction process, people can effectively manage their symptoms. This approach, ideally guided by a healthcare professional, allows for a personalized and varied diet that minimizes discomfort while maximizing overall gut health and nutrition. For comprehensive food lists and portion sizes, consulting reliable resources like the Monash University FODMAP app is highly recommended.(https://www.monashfodmap.com/ibs-central/i-have-ibs/starting-the-low-fodmap-diet/)

Frequently Asked Questions

What is the difference between fructans and GOS?

Fructans are sugar chains made of fructose units, while GOS are chains of galactose units. Both are poorly absorbed and fermented in the large intestine, but they are found in different food sources and an individual's sensitivity may differ for each.

Are fructans the same as gluten?

No, fructans and gluten are not the same. Fructans are a type of carbohydrate, while gluten is a protein. They are often confused because they are both found in wheat, rye, and barley, but fructans can cause digestive issues independently of gluten intolerance or celiac disease.

Can cooking reduce fructans and GOS in food?

Cooking methods can sometimes affect FODMAP content, but generally, high-fructan vegetables like onions and garlic will retain their fructan content even when cooked. Soaking and rinsing legumes can reduce GOS levels.

Which vegetables are high in fructans?

Vegetables high in fructans include onions, garlic, leeks, artichokes, beets, Brussels sprouts, savoy cabbage, fennel, and asparagus.

Which legumes contain GOS?

Common legumes containing GOS include baked beans, black beans, chickpeas, lentils, kidney beans, and soybeans.

What can I use instead of onion and garlic?

To get a similar flavor without the fructans, you can use the green parts of spring onions, chives, or garlic-infused oil. Fructans are not fat-soluble, so the oil is a great way to add flavor.

Do fructans and GOS cause problems for everyone?

No. In healthy individuals, fructans and GOS are beneficial prebiotics that feed good gut bacteria. Digestive issues typically only arise in sensitive individuals, such as those with IBS.