Which Digestive Enzyme Breaks Down What — Protein, Fat, Starch, Fiber, and Dairy

The single most useful thing to understand about digestive enzymes is that they are specific. Each one recognizes a particular chemical bond and cuts that bond and no other.

This has a practical consequence. If a heavy steak sits badly, more amylase will not help — amylase works on starch. If beans are the problem, protease is beside the point. Matching the enzyme to the food is the whole game, and it is the thing most product marketing skips over.

Here is the map, organized by food rather than by enzyme.

Protein — meat, fish, eggs, dairy, legumes

The enzymes: proteases and peptidases.

Protein is a long chain of amino acids folded into a shape. Digesting it takes two passes. Proteases cut the long chain into shorter fragments called peptides. Peptidases then cut the peptides into individual amino acids, which is the form your small intestine can actually absorb.

Protein digestion also happens across an unusually wide range of acidity. It starts in the strongly acidic stomach, where pepsin works, and continues in the near-neutral small intestine, where pancreatic proteases take over. No single protease is active across that whole range.

This is why a well-built panel lists more than one protease. It is not padding. Proteases with different optimal pH ranges cover different stretches of the journey. A formula with one protease is working on one part of it.

Protein-heavy meals worth thinking about: steak and roasts, large egg dishes, protein shakes taken all at once, and the high-protein plates that come with low-carb eating.

Starches and sugars — bread, pasta, rice, potatoes, fruit

The enzymes: amylase, glucoamylase, acid maltase, invertase.

Carbohydrate digestion is a relay, not a single step.

Amylase makes the first cut, breaking long starch chains into shorter fragments. It is the enzyme in your saliva, which is why chewing matters more for carbohydrates than for anything else on the plate.

Glucoamylase and acid maltase work on those shorter fragments, cutting them down to glucose. Without this second stage, starch is only partly digested — broken into pieces that are still too large to absorb.

Invertase handles sucrose — table sugar — splitting it into glucose and fructose. It is the one most often missing from a panel, and it is the one that matters for desserts, sweetened drinks, and most processed food.

A panel with amylase alone covers the opening move of carbohydrate digestion and not the follow-through.

Fat — oils, butter, nuts, fatty fish, fried food

The enzyme: lipase.

Fat is the most mechanically awkward macronutrient, because it does not dissolve in water and digestion is a water-based process.

Before lipase can do anything, bile from the gallbladder has to emulsify dietary fat into small droplets — the same principle as dish soap on a greasy pan. That emulsification creates the surface area lipase needs. Lipase then splits triglycerides into fatty acids and glycerol.

Fat digestion carries a consequence people underrate: fat-soluble vitamins depend on it. Vitamins A, D, E, and K are absorbed alongside dietary fat. So does much of the value of a fish oil or a tocotrienol supplement. When fat digestion runs inefficiently, absorption of those nutrients tends to run inefficiently too.

Meals worth thinking about: fried food, heavy cream sauces, large servings of nuts, and the sort of restaurant meal that is much richer than what you normally cook.

Dairy — milk, ice cream, soft cheese

The enzyme: lactase.

Lactose is the sugar in milk, and lactase splits it into glucose and galactose.

Lactase is the clearest case of enzyme output varying between people. Nearly everyone produces plenty in infancy. In a large share of the world's adults, activity declines substantially after early childhood — this is the ordinary human pattern, not a defect. A minority, concentrated in populations with long histories of dairy farming, keep high activity through adult life.

When lactose is not split, it passes undigested into the large intestine, where resident bacteria ferment it. That fermentation is what produces gas.

Lactose content varies a lot across dairy, which is worth knowing: milk and ice cream are high, soft cheeses are moderate, and aged hard cheeses and butter contain very little. Yogurt sits lower than its lactose content suggests, because its live cultures carry lactase of their own.

Beans, lentils, broccoli, cabbage — the fiber that fights back

The enzyme: alpha-galactosidase.

This one deserves its own section, because it explains a frustration a lot of people have with eating well.

Beans, lentils, chickpeas, broccoli, cabbage, cauliflower, and Brussels sprouts contain raffinose, stachyose, and verbascose. These are oligosaccharides — short carbohydrate chains built with an alpha-galactosidic bond.

Humans do not make an enzyme that cuts that bond. Not as children, not as adults. It is not something that declines with age; we never had it. So those carbohydrates arrive in the large intestine intact, where gut bacteria ferment them enthusiastically and produce gas as a byproduct.

Alpha-galactosidase is the enzyme that cuts that specific bond. It is the active ingredient in the familiar bean-and-vegetable products, and it is the reason the "healthiest" plate on the table is so often the uncomfortable one.

Cellulose — the fiber that is supposed to pass through

The enzyme: cellulase — which humans also do not make.

Cellulose is the structural fiber in plant cell walls. We cannot digest it, and in this case that is the point rather than a problem. Insoluble fiber is meant to pass through largely intact, and it does useful work along the way.

Supplemental cellulase is sometimes included in formulas to help break down plant cell walls and release nutrients held inside them, rather than to digest fiber for calories.

Matching a panel to your actual meals

Read the enzyme list against what you actually eat, not against what sounds comprehensive.

• Trouble concentrated after dairy — look for lactase, and check the activity

number rather than just the name.

• Trouble after beans and cruciferous vegetables — alpha-galactosidase is the

only enzyme that addresses those specific carbohydrates.

• Trouble after rich or fried meals — lipase.
• Trouble after large protein meals — multiple proteases across different pH

ranges, plus a peptidase.

• No clear pattern, or a varied diet — a broad-spectrum panel that covers all

of the above is more sensible than guessing at one.

One caveat worth stating plainly: a consistent, predictable reaction to a specific food is worth raising with a doctor rather than working around indefinitely. Some of those patterns have names and diagnoses, and an enzyme supplement is not a substitute for knowing which one you are dealing with.

How Healthy Tract's panel maps to this

Healthy Tract Digestive Enzymes carries eleven plant-sourced enzymes in one capsule, built to cover the whole map above rather than one corner of it:

• Starch and sugar — amylase (3,500 DU), glucoamylase (5 AGU), acid maltase

(14 MaltU), invertase (400 SU)

• Protein — three proteases across different pH ranges (21,000 HUT, 4,000 PC,

50 SAPU) plus a peptidase (2 AP)

• Fat — lipase (500 FIP)
• Dairy — lactase (1,000 ALU)
• Beans and cruciferous vegetables — alpha-galactosidase (150 GalU)

Each is printed by activity unit on the Supplement Facts panel rather than pooled into a single undisclosed blend weight. What those units mean, and why a milligram number tells you almost nothing, is covered in how to read a digestive enzyme label.

For the underlying mechanics of each enzyme family, start with what digestive enzymes actually do.

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.