What are digestive enzymes?
Digestive enzymes are proteins that break down complex nutrients into their subunits which are then absorbed in the intestine.
When we speak of digestive enzymes, we are mainly referring to enzymes produced by the pancreas, such as trypsin (a protease, which breaks down protein), pancreatic lipase (a lipase, which breaks down fat), and pancreatic amylase (an amylase, which breaks down starch). However, it’s worth noting that digestive enzymes are also produced by the salivary glands in the mouth, by cells in the stomach, and by cells in the small intestine.
In people, lactase and sucrase are also important digestive enzymes. Lactose intolerance is a common condition, and congenital sucrase-isomaltase deficiency is a rare cause of chronic diarrhoea in children.
What are animal-derived enzymes?
As mentioned above, the main digestive enzymes produced by dogs and cats are lipase, protease, and amylase. These enzymes are released into the intestine after meals, to assist with digestion of food. 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.
As veterinarians, when we recommend digestive enzyme supplements as part of a treatment plan for specific medical conditions, we are usually referring to products that contain porcine pancreatin or pancrelipase. They are commercial mixtures of amylase, lipase, protease and lactase, and brand names include Creon, Pancreaze, and Viokase.
Products intended for the treatment of exocrine pancreatic insufficiency and other diseases need to be properly formulated and dosed appropriately. They must be consumed with every meal to prevent maldigestion from occurring. These products often require a prescription from a veterinarian, and are very different to ‘over-the-counter’ digestive enzymes.
Over-the-counter digestive enzyme supplements for pets aren’t regulated in any way, so the dosage, ingredients and enzyme concentration aren’t guaranteed, and their side effects are unknown. Unfortunately, some supplements make claims that aren’t supported by evidence.
What are plant-derived enzymes?
Plant-derived enzymes include bromelain (a combination of protease enzymes from pineapples), papain (a protease enzyme from papaya), and cellulase (made by bacteria).The only approved clinical application for bromelain was issued in 2012 by the European Medicines Agency for a topical medication called NexoBrid, used to remove dead tissue in severe skin burns.
Even though bromelain and papain have been used a meat tenderisers for a long time, there’s no evidence that feeding bromelain or papain has any kind of beneficial gastrointestinal effects in dogs or cats. There is one study in mice that found that bromelain supplementation caused increased mucosal thickness in the ileum, increased paracellular permeability in the intestine, and increased trypsin activity in the pancreas, which was presumed due to increased liberation of amino acids from dietary protein.
Whether these are desirable outcomes is unknown at this stage. Work is ongoing on the anti-inflammatory and antioxidant effects of bromelain and papain, but again, we have no information on how to use these compounds safely and effectively.
Cellulase is made by bacteria in the gut of animals that eat grass or hay, and it breaks down cellulose, which is a type of fibre. Cellulase is not present in the intestine of dogs and cats. It is not clear why this is frequently included in digestive enzyme products for pets. Cellulose is an ingredient that is commonly found in commercial diets, however it is not intended to be digested! It is a non-fermentable fibre that may improve faecal consistency. If included in larger amounts, it can decrease the energy density of the diet, so it is often found in weight loss diets.
Do raw foods contain live enzymes?
I did a quick search for ‘raw food’ and ‘enzymes’, and this was the first thing that came up:
“Raw foods are enzymatically alive which means these foods have live enzymes within them to help digest 40 to 60% of that particular food. Cooked and processed foods are enzymatically dead which means there are no live enzymes within that food to help digestion.”
I find this quite a baffling statement! Individual cells do of course contain enzymes (intracellular enzymes). These are quite different to the digestive enzymes that we have considered previously (for example, pancreatic proteases, lipases and amylases). Intracellular enzymes generally act as catalysts for biological reactions in the cell. An example of an intracellular enzyme is citrate synthase, which catalyses the formation of citrate from oxaloacetate – an important step in the citric acid cycle.
Intracellular enzymes (like all enzymes) are proteins, and when we ingest raw food ingredients, our bodies will breakdown those proteins as part of the digestive process. So, these food-derived enzymes are very unlikely to reach the small intestine and affect nutrient absorption in any way. There’s no evidence that ingestion of intracellular enzymes (as part of raw foods) has any beneficial effect on digestion.
Is it safe to give digestive enzymes?
Treatment with digestive enzymes isn’t necessarily benign.
Side effects have been reported with digestive enzymes – mainly oral ulceration and/or oral bleeding, but also vomiting, diarrhea, and even severe allergic reactions (remember that pancreatin is porcine in origin, meaning that it contains pork proteins).
The risk of oral ulceration is higher with powdered supplements, compared with encapsulated enzymes. It is very important that powdered supplements are well-mixed into the food; also encourage drinking after the meal if possible.
In people, high doses of digestive enzymes have been (rarely) associated with the development of fibrosing colonopathy – this has not been reported in dogs or cats.
It’s also important to remember that supplementing your pet’s diet with any supplement may affect palatability – this is particularly the case for cats. Unnecessary administration of tablets and capsules can also cause unwanted stress for some animals.
Ageing and digestive enzymes
It is well-established that pancreatic exocrine function deteriorates with age. This has been shown in both rodent studies, and human studies.
An older rodent study demonstrated that aging induces modest changes in pancreatic digestive enzymes and in jejunal enteropeptidase, which the authors speculated were unlikely to be physiologically important. However, interestingly, they observed that the pancreas of ageing rats did not adapt to changes in dietary fat or sugar intake as well as young rats.
This may explain why older pets sometimes seem less able to cope with sudden dietary changes, and indeed there are some other studies that show that an effect of ageing on nutrient digestibility for both dogs and cats. In people, the incidence of exocrine pancreatic insufficiency increases with age, with studies showing that 5.6 to 21.6% of ‘healthy adults’ over the age of 70 have EPI.
So, what does this mean? Should all senior pets be given digestive enzymes? Currently, there’s no evidence to suggest that giving digestive enzymes to every older pet is likely to be beneficial. However, if your senior pet has signs like weight loss, loss of muscle mass, chronic soft stools or diarrhoea, or other chronic gastrointestinal signs, it is sensible to ask your vet to investigate further, and this could include measurement of serum TLI (trypsin-like immunoreactivity) to check exocrine pancreatic function.
Digestive enzymes for EPI, pancreatitis, and chronic gastrointestinal signs
Exocrine pancreatic insufficiency (EPI) is a syndrome that is characterised by a lack of pancreatic exocrine secretion (digestive enzymes) in the small intestine. It can occur in both dogs and cats, and is most commonly due to either chronic pancreatitis or pancreatic acinar atrophy. Signs include a ravenous appetite, weight loss, and chronic diarrhoea.
The disease can be diagnosed with a blood test (serum trypsin-like immunoreactivity (cTLI or fTLI)).
Treatment with pancreatin or pancrelipase is essential to prevent ongoing maldigestion and malabsorption. There is ongoing debate about whether powdered or encapsulated supplements are more effective.
For cats with EPI, administering pancreatic enzymes with every meal can be very challenging – this is especially the case for cats that like to graze. Usually feeding a high quality, moderate fat canned diet is the best option, as appropriate doses of enzymes can be mixed into the food. If feeding a dry diet, the enzymes can be mixed into pureed treats (e.g. Inaba Churu treats) and given immediately before a meal.
Unfortunately, evidence is lacking with respect to the benefits of digestive enzymes for acute and chronic pancreatitis in dogs and cats. There are some studies in humans that demonstrate a benefit of giving digestive enzymes early in an episode of severe, acute pancreatitis. There is mixed evidence with respect to whether administering digestive enzymes improves the pain associated with pancreatitis; one study suggested that only powdered enzyme supplements were effective.
For dogs or cats with severe, acute pancreatitis, there is enough evidence in other species to suggest that administering digestive enzymes with enteral feeding may be beneficial and is unlikely to be harmful.
For patients with chronic pancreatitis, it is sensible to monitor for signs of EPI, and also to remember that these signs may occur intermittently in association with periods of pancreatic inflammation.
So, should I give my healthy pet a digestive enzyme supplement?
The pet dietary supplement market is valued at over USD $3 billion, and gastrointestinal supplements are a top seller. Digestive enzymes are a popular product for companies that manufacturer pet supplements; they are often promoted required for optimal utilisation of nutrients.
However, for healthy dogs and cats with a normal pancreas, there is no evidence that supplementing digestive enzymes provides any benefits.
A study by Villaverde et al. (2017) supplemented healthy adult dogs with either plant- or animal-sourced digestive enzyme supplements and measured the effect of the supplements on the digestibility of their food. 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.
So – if your pet is healthy, we recommend giving the digestive enzymes a miss.
For some senior pets, or pets with specific medical conditions, supplementation of animal-derived digestive enzymes may be beneficial. However, this is something that needs to be properly diagnosed by your dog or cat’s veterinarian, and treated with the right dose of the right product.
If your pet has chronic gastrointestinal signs like diarrhoea, gut pain, borborygmi (increased gut sounds), flatulence and weight loss, please do discuss this with your vet, rather than beginning treatment with over-the-counter supplements like digestive enzymes.
It’s important to try and identify the cause of these signs, to ensure that the treatment is safe, effective and appropriate.
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