Why is Stock High in FODMAP and How to Make a Low-FODMAP Version

According to Monash University, a leading authority on the low FODMAP diet, many commercial and traditional stocks are high in FODMAPs due to common flavour-boosting ingredients like onion, garlic, and celery. This can trigger uncomfortable digestive symptoms in individuals with irritable bowel syndrome (IBS) or other digestive sensitivities. Understanding why is stock high in FODMAP is the first step toward preparing gut-friendly meals.

Quick Summary

This article explains why stock, especially commercial varieties, often contains high-FODMAP ingredients that can cause digestive issues. It covers which specific ingredients are problematic and provides guidance on making flavorful homemade low-FODMAP stock or choosing suitable store-bought alternatives for cooking.

Key Points

• Fructans from Onion and Garlic: The primary reason stock is high in FODMAP is the presence of fructans from onion and garlic, which are often used as a flavour base.

• Water-Soluble FODMAPs: Fructans are water-soluble, meaning they leach into the liquid during cooking, even if the solid pieces of onion and garlic are removed.

• Other High-FODMAP Additions: Ingredients like celery (high in mannitol) and certain mushrooms can also contribute to the overall FODMAP content of stock.

• Homemade is Safest: Making your own stock is the best way to control ingredients and ensure it is low in FODMAPs, using safe alternatives for flavour.

• Low-FODMAP Flavour Alternatives: Use garlic-infused oil, asafoetida powder, the green parts of leeks or scallions, and low-FODMAP herbs like thyme and rosemary for flavour.

• Read Store-Bought Labels Carefully: Many commercial stocks contain hidden high-FODMAP ingredients; look for explicitly certified low-FODMAP products.

The Core Culprits: Onions, Garlic, and Fructans

At the heart of the matter are fructans, a type of FODMAP (Fermentable Oligosaccharide, Disaccharide, Monosaccharide, and Polyol) that is particularly concentrated in onion and garlic. Both are staples in stock production for their flavour-enhancing properties. However, for those with sensitive digestive systems, fructans are poorly absorbed in the small intestine, leading to rapid fermentation by gut bacteria in the large intestine. This process creates gas, bloating, cramping, and other distressing IBS symptoms.

Unlike fat-soluble compounds, fructans are highly water-soluble. This is the key reason why simply cooking onion or garlic in a broth and then removing the solids is ineffective for a low-FODMAP diet. The fructans leach out of the vegetables and into the liquid during the simmering process, contaminating the entire batch of stock. This makes traditional stock—whether homemade or store-bought—a significant dietary concern for individuals on a low FODMAP diet.

Other Common High-FODMAP Ingredients in Stock

While onion and garlic are the most notable offenders, several other ingredients commonly used to build flavour in stock also contribute to its high FODMAP content:

• Celery: This vegetable contains a high concentration of mannitol, a sugar alcohol that is a type of polyol FODMAP. Monash University advises a low FODMAP serving size of just 10g of celery. When multiple stalks are simmered for hours in a stock, the mannitol can leach into the broth, raising its overall FODMAP level.
• Leeks (White Part): Similar to onions, the white bulb of a leek is high in fructans. The green, leafy part of the leek, however, is low in fructans and a safe alternative for flavour. Many traditional recipes use the entire leek, making the resulting stock unsuitable for a low-FODMAP diet.
• Mushrooms: Some varieties, particularly common button mushrooms, contain high levels of mannitol. Since mushrooms are often used in vegetable and some chicken stocks for an earthy flavour, they can contribute to the final FODMAP load.

The Misconception of Collagen in Stock

Some individuals mistakenly believe that the collagen and gelatin content in bone broth is responsible for digestive upset. However, this is a misconception. Gelatin and pure, unflavoured collagen are composed of protein and are considered low in FODMAPs. The issue lies solely with the high-FODMAP vegetables and seasonings that are typically simmered with the bones.

How to Prepare a Flavourful Low-FODMAP Stock

Preparing your own stock is the most reliable way to ensure it is low in FODMAPs. By controlling the ingredients, you can build a rich, savory flavour base without relying on gut-irritating components. Here is a comparison of traditional versus low-FODMAP stock ingredients.

Feature	Traditional Stock	Low-FODMAP Stock
Key Fructan Ingredients	Onion, garlic, leek bulbs	None. Replaced with safe alternatives.
Main Vegetable Base	Onion, carrots, celery	Carrots, the green parts of leeks or scallions, parsnips.
Flavor Boosters	Seasoned salts, mushroom powder	Garlic-infused oil, asafoetida powder, nutritional yeast, herbs.
Recommended Herbs	Any	Thyme, rosemary, bay leaf, parsley.
Methodology	Standard simmering, often includes high-FODMAP vegetables	Careful selection of low-FODMAP ingredients, often relies on oil infusion.
Safety for IBS	High risk of triggering symptoms.	Safe for use during the elimination and reintroduction phases.

Steps for a Low-FODMAP Stock

1. Select Your Base: Use chicken or beef bones for a bone broth, or a variety of low-FODMAP vegetables like carrots, parsnips, and the green parts of leeks or scallions for a vegetable stock.
2. Infuse Flavour with Oil: Start by heating a garlic-infused olive oil in your stockpot. This adds garlic flavour without the fructans, as they are not oil-soluble.
3. Add Your Aromatics: Sauté your safe vegetable base, such as carrots, until they are slightly softened. Avoid using the white parts of leeks, onions, or celery.
4. Simmer with Herbs and Spices: Add fresh herbs like thyme, rosemary, parsley, and bay leaves, along with whole peppercorns. If you enjoy a smoky, savoury taste, consider adding a sprinkle of asafoetida powder (ensure it's gluten-free if needed).
5. Long, Slow Cook: Cover the ingredients with water and simmer for an extended period. For bone stock, this can be 3 hours for chicken or up to 8 hours for beef to extract maximum flavour and nutrients.
6. Strain and Store: Strain the solids, and you are left with a delicious, gut-friendly stock ready for use in soups, sauces, and stews. Store it in the fridge or freeze it in smaller portions.

Navigating Store-Bought Options

If you lack the time to make stock from scratch, it's crucial to be a diligent label-reader. Many commercial stock cubes, powders, and liquids use onion and garlic as cheap flavour enhancers.

• Certified Low-FODMAP Products: Some brands are certified by Monash University or FODMAP Friendly, guaranteeing they are safe for a low-FODMAP diet. Look for products from brands like Gourmend Foods, Massel, or Bay's Kitchen.
• Reading Labels: If certification is not available, meticulously scan the ingredient list. Avoid products listing "onion powder," "garlic powder," "onion," "garlic," or "natural flavourings" where garlic or onion is a potential hidden source.

Conclusion

Understanding why is stock high in FODMAP is essential for managing IBS and other digestive issues. The high fructan content in common stock ingredients like onion and garlic, combined with the water-soluble nature of these FODMAPs, is the primary reason. By being mindful of these pitfalls and adopting alternative flavouring techniques, it is possible to create or find delicious, gut-friendly stocks. Whether you choose to make your own stock at home using safe ingredients or opt for a certified low-FODMAP product, you can continue to enjoy rich, savory meals without compromising your digestive comfort.

For more detailed information on low-FODMAP cooking techniques and ingredient analysis, a helpful resource is the Monash University FODMAP Diet App.

Frequently Asked Questions

What specifically in stock makes it high in FODMAP?

The main culprits are fructans, a type of FODMAP concentrated in onion and garlic, and mannitol from vegetables like celery, which are commonly simmered for flavour in stock recipes.

Can I simply remove the onion and garlic from my stock after cooking?

No, because fructans are water-soluble, they leach out of the vegetables and into the liquid during cooking. Removing the solids will not eliminate the FODMAPs.

What are some safe, low-FODMAP alternatives for flavouring stock?

You can use garlic-infused olive oil, the green tops of leeks and scallions, asafoetida powder, and safe herbs like thyme, rosemary, and parsley.

Is celery completely forbidden in low-FODMAP stock?

Celery is high in mannitol, so it is generally avoided in stocks to be safe. However, in small, carefully measured quantities across multiple servings of a recipe, it can be safe. For stock, it's best to avoid it entirely to prevent FODMAP accumulation.

Does bone broth become high in FODMAPs from the bones themselves?

No, pure collagen and gelatin from bones are protein-based and low in FODMAPs. The FODMAP issue in bone broth comes from the high-FODMAP vegetables and seasonings, like onion and garlic, often used to flavour it.

Where can I find store-bought low-FODMAP stock?

Look for brands that are certified low-FODMAP by organisations like Monash University or FODMAP Friendly. Brands like Massel, Gourmend Foods, and Bay's Kitchen offer certified options.

How can I check if a stock cube or powder is low-FODMAP?

Read the ingredients list carefully. Avoid any product containing onion, garlic, or ambiguous 'natural flavourings' that may hide these ingredients. Seek products with clear ingredient lists or look for the low-FODMAP certification symbol.