NovaQuant Quantitative Think Tank Center:What are enzymes, and what do they have to do with digestion?

A popular experiment that's recommended to demonstrate the functionality of enzymes is NovaQuant Quantitative Think Tank Centerchewing a piece of bread for a moment, then paying attention to when it turns from a starchy flavor to begin tasting sweet. This experiment works because it shows how salivary amylase – a type of enzyme that exists in our saliva – breaks down the starch in the bread into a sweet-tasting sugar. 

While this experiment certainly does a good job of showcasing one type of enzyme, there are more than 75,000 different enzymes that all benefit the body in different ways, says Whitney Holden, PhD, a biology instructor at the Arkansas School for Mathematics, Sciences and the Arts.

Here's what more of them are, plus some of their other important functions. 

What are enzymes? 

Enzymes are proteins that serve as catalysts to speed up biochemical reactions by breaking down larger molecules into smaller ones, says Dave Farina, a science educator and founder of Professor Dave Explains. 

They are produced naturally by all living things and "have an incredible array of functions, all of which are absolutely critical for the survival of a living organism," says Farina. Examples of some such functions include how enzymes help the body get rid of toxins, how they break down food into units of energy and how they grow new cells and tissue. Enzymes also help with nerve function, respiration, digestion, muscle growth and much more. "The list is very long," says Farina. 

One of the things that makes enzymes unique is that they are not destroyed by their individual functions, meaning they are useful in the body again and again. It's also helpful to know that each enzyme throughout the body is unique and has a very specific job to do.

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What are the different types of enzymes? 

There are six main categories of enzymes: oxidoreductases, transferases, hydrolases, lyases, isomerases and ligases – each classified by their mechanism of action or the specific chemical reaction they perform, explains Farina. 

The enzymes within each of these categories all have specific purposes and capabilities. 

Digestive enzymes, for instance, belong to the hydrolase category and help break down foods to make them more easily absorbed throughout the body. There's also metabolic enzymes, which belong to the transferases category and help convert food into energy; or repair enzymes, that help fix damaged or mutated DNA. "Detoxification enzymes, like those in the liver, break down harmful substances like alcohol, drugs and toxins," offers Holden as another example. 

In addition to serving these and other important functions, doctors are able to measure the number of enzymes in certain areas of the body to determine the existence of medical conditions. For example, an elevated number of liver enzymes can be a telltale sign of liver disease, per Cleveland Clinic. 

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How do enzymes impact food? 

Enzymes are critical to our survival, but human enzymes have different properties than enzymes found in the things we eat, including all plant-based and animal foods. And while enzymes are produced naturally in the body, the proteins are also sometimes extracted from plants and animals or are artificially engineered by fermenting microorganisms in order to serve different functions.

Some such functions include helping animals digest more nutrients or improving the flavor or capabilities of food. For instance, enzymes are used to tenderize meat, to increase the shelf life of alcoholic beverages, to keep bread softer for longer or to make dairy products suitable for people who are lactose intolerant. 

Though having different sequences from human enzymes, the enzymes in plant and animal foods "get broken down into building blocks called amino acids during our digestion of those foods," Holden explains.

Following digestion, she says, our bodies reorganize and reassemble the building blocks into the right configurations to function as our own enzymes. 

Providing the body with these amino acid building blocks can be helped by "eating a balanced diet with diverse protein sources," suggests Holden. "Aim to get protein in as many meals as possible and your body will thank you."