Digestive Enzymes for Allergies and MCAS: Choosing the Right Type

If you have food allergies or mast cell activation syndrome (MCAS), the type of digestive enzyme you choose matters as much as whether you take one at all.

Most "plant-based" enzymes are actually made by fungi, and sometimes that alone is enough to trigger symptoms in some of my sensitive clients.

In clinic, I like to think about enzymes in four tiers:

Tier 1: all-round support (protein, carbohydrates and fats)
Tier 2: carbohydrate and fibre support
Tier 3: animal-based enzymes for people who react to fungal enzymes
Tier 4: prescription enzyme therapy for those who've had medical investigations and require it

Here's a little more detail about each of them.

Plant, fungal or animal: what's really in your enzyme

The enzymes in most vegan formulas are grown from fungi, usually Aspergillus species. You'll often see this on the label as aspergillopepsin, or as enzymes measured in units such as SAPU, HUT, DU or FIP. A few come from fruit, such as bromelain from pineapple and papain from papaya.

For most people this is fine. For someone with mould sensitivity, MCAS or multiple food allergies, fungal enzymes, fruit enzymes and the fillers that come with them can all be a source of reactions.

Animal-based enzymes, mostly porcine pancreatin, are the alternative. They're closer to what your own pancreas makes, but they aren't suitable for everyone, including vegetarians, vegans and some faiths, and pancreatin itself can occasionally be an allergen.

Tip: check the full label, not just the front. Some "animal" formulas still contain a fungal protease, and some contain sulfites.

Tier 1: All-round support

For low-level digestive support, such as heaviness after meals, bloating with protein or fatty foods, or signs of low stomach acid, I like a combined formula with enzymes, a little ox bile and betaine HCl.

NOW Super Enzymes
Why I use it: my go-to for general support
What's in it: betaine HCl, ox bile extract, porcine pancreatin, bromelain, papain, cellulase and a small amount of fungal protease (aspergillopepsin)
Watch for: the capsule is gelatin and the product contains sulfites. It has both fruit and fungal enzymes, so it isn't the right choice for very reactive clients.

Betaine HCl isn't suitable if you have ulcers or gastritis, or take acid-reducing medication such as PPIs.

Tier 2: Carbohydrate and fibre support

When the main issue is carbohydrates, beans, vegetables or fibre, a broad-spectrum microbial blend usually works better. These contain enzymes that animal pancreatin doesn't, such as alpha-galactosidase (for beans and pulses), cellulase, hemicellulase, lactase and phytase.

NOW Digest Ultimate
What's in it: a full-spectrum vegan blend where almost every enzyme is grown from Aspergillus oryzae or Aspergillus niger, in a cellulose capsule with MCT oil
Watch for: effective, but fully fungal, so not for mould-reactive clients

Allergy Research Group Full Spectrum Digest
What's in it: a vegan blend with Glutalytic, lactase, lipase, alpha-galactosidase and amylase, aimed at gluten, dairy, protein, fat and carbohydrate breakdown
Watch for: still microbial, but from a brand that formulates for sensitive people

Tier 3: Animal-based options for fungal reactors

If someone reacts to plant or fungal enzymes, I switch to a pure pancreatin product with as few extras as possible.

Thorne Pancreatic Enzymes (formerly Dipan-9)
Source: undiluted porcine pancreatin, lactose free
Also contains: hypromellose capsule only
Best for: the cleanest label, for very sensitive clients

Pure Encapsulations Pancreatic Enzyme Formula
Source: 500 mg lactose-free porcine pancreatin
Also contains: acid-resistant vegetarian capsule, cellulose
Best for: a clean label that's widely available in the UK

Allergy Research Group Pancreas glandular
Source: freeze-dried pancreas tissue (pork, lamb or beef)
Also contains: HPMC capsule, cellulose, magnesium stearate, silica
Best for: rotating species in highly sensitive clients

Klaire Labs SpectraZyme
Source: 360 mg porcine pancreatin
Also contains: tablet binders and disintegrants
Best for: higher strength, though less clean than the capsules

One caution: pancreatin can itself be an allergen, and research has shown cross-reactivity between pork and beef pancreatin. With very reactive clients, I start with a fraction of a dose and build up slowly.

Tier 4: Prescription enzyme therapy

Some people need medical investigation rather than a supplement. Signs such as pale, oily or floating stools, unexplained weight loss or ongoing fat malabsorption can point to pancreatic exocrine insufficiency (PEI), and that needs your GP.

In the UK, pancreatic enzyme replacement therapy (PERT) is prescribed as Creon, Nutrizym or Pancrex. These are all made from pork, and there is no vegetarian alternative on prescription. PERT is used mainly for PEI caused by pancreatitis, pancreatic surgery, pancreatic or neuroendocrine cancers and cystic fibrosis.

UK supply has been patchy for several years, and imported brands such as Pangrol and Kreon have been used to fill gaps.

Before you start

Start low. Take one capsule at your main meal, and only increase if you tolerate it well.

Read the whole label. Check the capsule material, fillers, sulfites and any fungal or fruit enzymes hidden in an "animal" formula.

Enzymes support digestion; they don't fix the reason it isn't working. Ongoing symptoms deserve proper investigation.

Avoid betaine HCl if you have ulcers or gastritis, or take acid-reducing medication.

Check first with your GP or practitioner if you're on medication or have a diagnosed condition.

Read next

If you think you're struggling with histamine, DAO (diamine oxidase) is a different kind of enzyme that can help break down histamine from food and drink. I explain what it is, who it suits and how the UK options compare on price and ingredients in DAO for Histamine Intolerance and MCAS: What It Is and UK Options Compared.

Sources

Pancreatic Cancer UK: PERT
Guts UK: PERT supply update, April 2025
Pancreatic Cancer UK: PERT shortage factsheet, April 2025
NOW Super Enzymes label
NOW Digest Ultimate label
Baur et al. (1984): enzymes as allergens in pancreatin