What is the FODMAP GOS and How to Manage Digestive Discomfort

Found naturally in foods like lentils, chickpeas, and cashews, galacto-oligosaccharides (GOS) are prebiotic carbohydrates that feed the beneficial bacteria in your gut. However, while GOS support gut health for many people, they can trigger uncomfortable digestive symptoms in some, especially those with irritable bowel syndrome (IBS).

Read on to learn about the science behind GOS, why they can be challenging to digest, and practical strategies for managing GOS intolerance, including using digestive enzymes and making smart, low-GOS food swaps.

What Are Galacto-Oligosaccharides (GOS)?

GOS are short-chain carbohydrates that are made of 2-8 galactose sugars joined together with a glucose sugar on one end. Found in common foods like lentils, chickpeas, and cashews, they have numerous health benefits because they act as a prebiotic— food for the good bacteria in your gut.

The science behind GOS (galacto-oligosaccharides)

GOS can be broken down by an enzyme called alpha-galactosidase. However, humans lack this enzyme. This means that GOS move into the large intestine undigested. Here, they get fermented by the gut bacteria. This can cause bloating, excess gas, and other irritable bowel syndrome (IBS) symptoms.

How GOS fits into the FODMAP family

GOS fall under the "O" in FODMAP, which stands for "oligosaccharides." FODMAPs are fermentable carbohydrates that can trigger symptoms in people with a FODMAP intolerance, such as those with IBS.

Why GOS Can Cause Digestive Issues

Since humans lack the enzymes needed to break down GOS, they pass into the large intestine undigested. They then get fermented by the gut bacteria. While this microbial fermentation is a natural process that benefits gut health for many people, it can cause significant discomfort for others.

The fermentation process and gut discomfort

When the gut bacteria ferment GOS in the large intestine, they produce gases like hydrogen, methane, and carbon dioxide as a byproduct of fermentation. This rapid gas production can stretch the walls of the large intestine, leading to sensations of bloating and abdominal discomfort.

GOS can also draw water into the bowel, which can lead to diarrhea (or even a combination of diarrhea and constipation). This gas and water movement can trigger digestive symptoms in people who are extra sensitive to digestive sensations, a phenomenon referred to as visceral hypersensitivity.

Common symptoms of GOS intolerance

People who are intolerant to GOS may experience a range of digestive symptoms, including:

  • Bloating
  • Excessive flatulence
  • Abdominal pain or cramping
  • Diarrhea
  • Constipation

Foods High in GOS FODMAPs

GOS are naturally found in many plant-based foods, particularly legumes.

Legumes and other GOS-rich foods

Here are some of the most common GOS-rich foods:

  • Lentils
  • Chickpeas
  • Kidney beans
  • Black beans
  • Pinto beans
  • Navy beans
  • Split peas
  • Soybeans (and soy-based products like soy milk made from whole soybeans and soft tofu)
  • Cashews
  • Pistachios
  • Almonds
  • Pine nuts
  • Beets
  • Bitter melon
  • Green peas
  • Taro
  • Tuscan Kale
  • Turnip
  • Oat milk

For the most up-to-date information about which foods are high in GOS, use the Monash University app.

Hidden sources of GOS in your diet

While legumes are well-known for their GOS content, they're not the only foods that contain GOS. Some hidden sources include:

  • Plant-based protein powders: Those made with pea or soy protein isolate may be high in GOS.
  • Dairy alternatives: Soy milk (made from whole soybeans) and certain nut-based yogurts can contain GOS.
  • Processed foods: Certain soups, vegetarian burger patties, or dips may use legume flours or whole legumes as ingredients.
  • Prebiotic supplements: Products with added prebiotics may use GOS to increase the fiber content.

Tips for Managing GOS Intolerance

If you think you may have a GOS intolerance, making small changes to your diet may help reduce symptoms like gas and bloating.

Simple steps to reduce GOS intake

Here are some simple steps to reduce GOS intake:

  • Use canned legumes: Canned legumes (like lentils and chickpeas) are lower in GOS than fresh or dried beans because some of the GOS leach out during the canning process. Drain and rinse them thoroughly to remove the excess GOS.
  • Replace cashews, almonds, and pistachios: Choose nuts that don't contain large amounts of GOS, like macadamias, pecans, or walnuts.
  • Dairy-free alternatives: Choose low-GOS dairy-free alternatives, like almond milk or dairy milk (if you're lactose intolerant, use the digestive enzyme lactase, which can help you tolerate lactose in dairy products).
  • Adjust portion sizes: Many high GOS foods are tolerable in smaller amounts. Try eating small servings and monitor your symptoms.
  • Read labels: Watch for hidden sources of GOS in processed foods like veggie burgers (which may be soy-based), protein bars, protein powders, or foods with added prebiotics. Look for words like "soy," "soy protein isolate," and "pea protein," which indicate a food may contain GOS from these foods.

Low-GOS alternatives for everyday meals

Here are some low-GOS swaps for everyday meals:

  • Breakfast: Switch your soy or oat milk for almond milk or dairy milk (use the digestive enzyme lactase if you're lactose intolerant, as this digestive enzyme can help you tolerate the lactose in dairy products).
  • Lunch: Replace kidney beans with canned chickpeas (rinse well) or grilled chicken in a salad.
  • Dinner: Swap a bean-based chili for one made with minced turkey and zucchini or eggplant.
  • Snacks: Choose low-GOS dips like yogurt with herbs instead of hummus. Pair with carrot sticks, cucumber, or rice crackers.

How GOS Fits into the Low-FODMAP Diet

GOS are one of the five types of FODMAPs. The acronym FODMAP stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols. The members of the FODMAP group are short-chain carbohydrates that are poorly absorbed in the small intestine. Eating high FODMAP foods can cause gut symptoms in people with IBS, who often have a FODMAP intolerance.

Understanding GOS in relation to other FODMAPs

GOS fall into the "oligosaccharides" category, along with fructans. They're temporarily reduced during the low-FODMAP diet as a way to get symptoms under control and see whether they trigger symptoms. However, the low-FODMAP diet should not be followed forever, and FODMAPs, including GOS, should be reintroduced eventually, as they play an important role in supporting a healthy gut microbiota. For best results, work with a registered dietitian who can help you reintroduce high-FODMAP foods strategically.

Digestive Support for GOS Intolerance with FODZYME

Foods containing GOS are hard to digest because humans lack the enzymes needed to break them down in the small intestine. Fortunately, digestive enzyme supplements can help break down the GOS your body can't.

How digestive enzymes can help break down GOS

FODZYME contains three digestive enzymes. One of these enzymes is alpha-galactosidase, which targets the GOS in foods like beans, lentils, and certain nuts. By breaking the GOS down into simpler, more digestible sugars, FODZYME can help reduce gas production, minimize bloating, and improve overall digestive comfort. 

Discover FODZYME for relief from GOS-related symptoms and add high GOS foods into your diet worry-free.