the scientific study of pet nutrition by veterinary nutrition specialists and experts.

Digestive Enzyme Supplements: Breaking Down the Evidence

Digestive Enzyme Supplements: Breaking Down the Evidence
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Gastrointestinal issues such as vomiting, diarrhea, and gas are common occurrences in dogs and cats and can have many causes ranging from minor to life-threatening. When a pet is frequently afflicted with gastrointestinal issues, pet owners often look for solutions involving diet or dietary supplements. Two common dietary supplements that are often used in pets with gastrointestinal issues (or as a means to prevent issues) are probiotics (which we discussed in an earlier post) and digestive enzymes.

Digestive enzyme supplements can be very appealing to owners of pets with frequent signs of digestive distress. There are dozens of products available that make claims such as “may dramatically improve your pet’s digestion and absorption of nutrients”, “replace vital food enzymes destroyed by cooking”, and “contribute considerably to your pet’s well-being”. There are even some sources that claim that your pet could develop serious or even fatal health problems if you don’t supplement digestive enzymes. So what is true? Does supplementing digestive enzymes make your pet healthier and will your pet get sick if you don’t? The short answer is “no”.

Digestive enzymes are proteins that break down complex nutrients into their subunits which are then absorbed in the intestine. The main digestive enzymes in pets are lipase (for fat), protease (for protein), and amylase (for starch). These enzymes are made in the pancreas and released into the intestine after meals. In the vast majority of animals, these enzymes do exactly what they are intended to do – they digest the food and are critical to nutrient absorption. Another enzyme, cellulase (which is made by bacteria in the gut of animals that eat leaves or hay), can break down a common type of fiber (cellulose) and is not present in the intestine of dogs and cats.  However, for unknown reasons, cellulase is often included in plant-based enzyme supplements.

In dogs and cats with pancreatic damage or a specific disease called exocrine pancreatic insufficiency (EPI), the pancreas is unable to produce enough enzymes. EPI is a disease that causes destruction of the enzyme-producing part of the pancreas and is most common in German shepherd dogs but can occur in other dog breeds and in cats. It’s important to know that this is not a common disease and dogs and cats with EPI usually have pretty dramatic symptoms – they are voraciously hungry but typically underweight and often have constant, smelly diarrhea. The disease can be confirmed with a blood test and by usually dramatic response to high quality animal-based digestive enzyme supplements that typically can be purchased only through a veterinarian.

For animals with a normal pancreas, there is no proof that supplementing with additional enzymes has any benefits for digestion or for overall health. One recent study supplemented healthy dogs with either plant- or animal-sourced digestive enzyme supplements and measured the effect of the supplements on the digestibility of their food.(1)  The study found that the digestibility of the calories in the diet – as well as protein, fat, and carbohydrate – was not different between the two supplements, or when the dogs did not receive a supplement, meaning that there was no benefit seen of either supplement.

And claims that your otherwise healthy pet needs to be supplemented because the natural enzymes in his food have been killed by cooking are not valid – the enzymes naturally occurring in food have more to do with why food spoils than being necessary for digestion, so “killing” them by cooking isn’t going to make any measurable difference for your pet. Moreover, treatment with digestive enzymes isn’t necessarily without some risk as well. Side effects have been reported with digestive enzymes – mainly oral ulceration but also vomiting, diarrhea, and even severe allergic reactions. And because the quality control of supplements, including digestive enzymes, is so variable, there are few guarantees that the products actually contain active digestive enzymes and don’t contain unsafe contaminants.

So, while many of these products may be advertised as if they are critical to your pet’s health and would provide many benefits, they are very unlikely to live up to the hype. Unfortunately, like many nutritional supplements, enzyme supplements for healthy pets are often a case where the science doesn’t support the marketing!


  1. Villaverde, C., et al. (2017). “Effect of enzyme supplements on macronutrient digestibility by healthy adult dogs.” J Nutr Sci 6: e12.

Dr. Cailin Heinze is a Board-certified Veterinary Nutritionist® and the Executive Director and Chief Academic Officer of the Mark Morris Institute, a non-profit organization whose mission is to promote optimal companion animal health by providing educational opportunities for veterinary students and veterinarians in clinical nutrition. She has also done some consulting work for Balance IT, a company that makes software and supplements for home-cooked pet diets. She is an expert in home-cooked diet formulation and general pet nutrition and has a special interest in feeding pets with kidney disease and cancer.

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