Digestive Enzymes Explained: Protease, Lipase, Amylase and Why mg Tells You Nothing (2026 Australian Guide)

Enzymes are measured in activity units, not milligrams — which makes most label comparisons meaningless. What HUT, FCC, DU, FIP and SAPU mean, which enzyme handles which food group, and the five label problems to watch for.

By Health & Heal

October 22, 2026 5 min read

Milligrams are the wrong unit for an enzyme

This is the single most useful thing to understand about digestive enzyme supplements, and almost no marketing explains it.

For a vitamin or a mineral, milligrams tell you how much you are getting. For an enzyme, milligrams tell you the weight of the powder — not how much work it can do. An enzyme is a catalyst. What matters is its activity, and activity is measured in its own units.

A product listing "Protease 100mg" has told you almost nothing. A product listing "Protease 20,000 HUT" has told you something you can compare.

Two capsules can contain the same milligram weight and differ many times over in activity, depending on how concentrated the enzyme preparation is.

The activity units you will see

There is no single universal unit. Each enzyme class has its own, and some have several. This is the main reason enzyme labels are hard to compare.

Protease (protein)

HUT — Haemoglobin Unit, Tyrosine base. The most common on consumer labels
PC — Protease, Casein units
SAPU — Spectrophotometric Acid Protease Units, for acid-stable proteases
FCC PU — Food Chemicals Codex Protease Units

Lipase (fat)

FIP — Fédération Internationale Pharmaceutique units
LU — Lipase Units
FCC LU

Amylase (starch)

DU — Dextrinising Units. The usual one
SKB — Sandstedt, Kneen and Blish units
FCC DU

Others

Cellulase — CU (Cellulase Units)
Lactase — ALU (Acid Lactase Units) or FCC LacU
Invertase — INVU or SU
Alpha-galactosidase — GalU
Bromelain — GDU (Gelatin Digesting Units) or MCU (Milk Clotting Units)
Papain — TU (Tyrosine Units) or PU

The practical rule: you can only compare two products if they use the same unit for the same enzyme. HUT against SAPU is not a comparison. Neither is 100mg against 20,000 HUT.

Which enzyme handles which food group

Protease / peptidase	Protein
Lipase	Fats and oils
Amylase	Starch
Lactase	Lactose, the sugar in milk
Cellulase	Cellulose — plant fibre
Alpha-galactosidase	Oligosaccharides in legumes and brassicas
Invertase / sucrase	Sucrose — table sugar
Maltase / glucoamylase	Maltose and starch fragments
Phytase	Phytic acid in grains, nuts and seeds
Bromelain	Protein. From pineapple
Papain	Protein. From papaya

Note that humans do not produce cellulase, and the alpha-galactosidase picture is limited too. Those are supplied by enzyme preparations rather than supplementing something the body makes in quantity.

Where the enzymes come from

Microbial and fungal

Most enzymes in supplements are fermentation-derived, usually from Aspergillus oryzae, Aspergillus niger, Rhizopus or Trichoderma. These are vegetarian and vegan suitable, and tend to be active across a wider pH range than animal-derived equivalents.

Plant

Bromelain from pineapple stem, papain from papaya. Both proteases.

Animal

Pancreatin — a mixture of protease, lipase and amylase from porcine or bovine pancreas. Usually measured in USP units and often expressed as a strength multiple such as 4X or 8X, meaning four or eight times the minimum USP specification.

Ox bile is sometimes included alongside lipase. It is a bile salt, not an enzyme.

Systemic enzyme products such as nattokinase and serrapeptase are a separate category again — those are fermentation-derived proteases measured in their own units (FU and SPU), and they are not digestive enzyme preparations.

pH matters more than people expect

An enzyme only works within a particular pH window. The stomach is strongly acidic; the small intestine is not. An enzyme that only functions at intestinal pH will be inactive while it is in the stomach, and vice versa.

This is why you will see:

Acid-stable proteases — measured in SAPU, designed to keep working in stomach acid
Enteric coating — a coating that does not dissolve until it reaches the intestine, protecting the enzyme on the way through

Pancreatin products are frequently enteric coated for this reason. Microbial preparations frequently are not, because they tolerate a broader pH range.

Label implication: "take with food" or "take with the first few bites" on an enzyme product is about pH and transit timing, not a formality. Our guide to when to take your supplements covers the with-food question across other categories.

Five label problems to watch for

1. Milligrams only, no activity units. The most common. You cannot evaluate the product.

2. A proprietary blend with one total weight. "Enzyme Blend 250mg" across nine enzymes tells you nothing about any individual one. The ones listed first are present in the largest amount, and that is all you know — the same structural problem covered in why supplements have 20 ingredients.

3. A long list with no activity figures. Fourteen enzyme names looks thorough. Without units, a trace of each would produce the same label.

4. Mixed units across the same enzyme in a range. Makes two products from the same brand incomparable, let alone two brands.

5. No allergen declaration on plant enzymes. Bromelain and papain are proteases from fruit. Check the Contains statement regardless — see our guide to allergens in supplements.

Serving size is part of the number

An easy comparison trap. One product lists its activity per two capsules, another per one capsule. The first looks twice as strong and is not.

Always read the activity figure together with the serving size it refers to, then divide down to per-capsule before comparing anything.

The short version

Ignore milligrams on an enzyme label — they describe powder weight, not capability. Look for activity units: HUT for protease, FIP or LU for lipase, DU for amylase. Only compare like units for like enzymes. Check the serving size the figure refers to. Treat a proprietary blend with a single total weight as unquantified.

Enzyme labels are among the hardest in the supplement aisle to read, and that is largely because the units are unfamiliar rather than because the products are complicated.