Digestive enzymes, probiotics and prebiotics: what is the difference?

Digestive enzymes, probiotics and prebiotics sit side by side on pharmacy shelves, and their names sound alike. They are three different things. An enzyme is a protein that works on food. A probiotic is a living microorganism. A prebiotic is a part of food that the body does not digest, and that the microorganisms in the gut can use.

This article sets out what each one is, where it is found and what it does, using the definitions of the US National Institutes of Health (NIH), the UK's National Health Service (NHS) and the scientific literature.

How do they compare at a glance?

The sections below explain each column, with the source for each point.

What are digestive enzymes?

The US National Library of Medicine (MedlinePlus) describes enzymes as complex proteins that cause a specific chemical change, such as helping to break down the foods we eat so the body can use them. They are not alive.

Your body makes its own. According to NIDDK, part of the NIH, enzymes are added to food in saliva, in the stomach, in the juice from the pancreas and in the small intestine, and bacteria in the small intestine make some of the enzymes needed to digest carbohydrates. A few foods contain enzymes too, such as bromelain in pineapple and papain in papaya.

An enzyme supplement brings together enzymes that work on food. For the full picture, read What do digestive enzymes do?.

What are probiotics?

The US National Center for Complementary and Integrative Health (NCCIH) defines probiotics as live microorganisms that are intended to have health benefits when consumed. The most common are bacteria from the groups Lactobacillus and Bifidobacterium; yeasts such as Saccharomyces boulardii are also used.

The NIH Office of Dietary Supplements (ODS) adds some practical points:

• Probiotics are named by genus, species and strain. In Lacticaseibacillus rhamnosus GG, for example, GG is the strain. Different strains can behave differently.
• Fermented foods are made with microorganisms. Yoghurt, cheese, sourdough bread, pickles, kimchi, sauerkraut, miso and kombucha are examples, but not all of them contain probiotics with proven health benefits.
• Counts are given in colony-forming units (CFUs). A higher CFU count alone does not necessarily mean a greater benefit. Any benefit depends on the specific strains and their number.
• Probiotics act mainly in the digestive tract. Research on how they affect health is ongoing, and results vary with the strain studied.

Both the NIH and the NHS are cautious. NCCIH notes that in most cases it is still not known which probiotics are helpful and which are not, and the NHS says there is little evidence to support many of the health claims made about them. The NHS also points out that probiotics are generally classed as food rather than medicine, so it cannot always be certain that a product contains the bacteria on its label, in sufficient numbers, or that they survive to reach the gut.

What are prebiotics?

NCCIH defines prebiotics as nondigestible food components that selectively stimulate the growth or activity of desirable microorganisms. In other words, they are food for some of the microorganisms in your gut, rather than for you directly.

A 2017 review in the journal Gut Microbes explains how prebiotics relate to fibre: not all fibres can be classed as prebiotics, but most prebiotics can be classed as dietary fibre. One well-studied group, inulin-type fructans, is found naturally in agave, artichokes, asparagus, bananas, chicory root, garlic, onions, leeks and wheat.

Because prebiotics are not digested by your own enzymes, they reach the large intestine, where gut bacteria use them. The Fibre enzymes article explains why the human body breaks down so little fibre on its own.

And what are synbiotics?

NCCIH describes synbiotics as products that combine probiotics and prebiotics in one.

So how do the three differ?

Put simply:

• An enzyme is a tool. It is a protein that breaks a specific part of food into smaller parts. It is not alive and does not grow.
• A probiotic is a living organism. Its effects depend on the strain, and research on them is still developing.
• A prebiotic is food for gut microorganisms. It passes your own digestion and is used further along the gut.

They are not interchangeable: an enzyme is not a living organism, and a prebiotic does not do an enzyme's work of breaking down food.

Who should ask before taking probiotics?

The ODS notes that there are no official recommendations on probiotics for healthy people, and suggests asking your doctor which product to choose and how to use it. Probiotics might not be safe for everyone: according to the ODS, they may cause problems in premature babies and in people who are already seriously ill. The NHS advises talking to a doctor before taking probiotic supplements if you have an existing health condition.

Where does Goodness Digestive Enzymes fit in?

Goodness Digestive Enzymes belongs to the first column: it is an enzyme supplement, with 13 enzymes that help break down protein, starch and sugars, fats and plant fibre. It is a food supplement that supports healthy digestion, and it does not replace a varied, balanced diet.

The four groups of enzymes are explained in Protein enzymes, Carbohydrate enzymes, Lipase and fat digestion and Fibre enzymes. If you take medicines or have a sensitivity to certain foods, read Digestive enzymes, medicines and allergies first. The How to use page gives the directions and safety notes, and the FAQ answers other common questions.