Enzyme therapy is a plan of dietary supplements of plant and animal enzymes used to facilitate the digestive process and improve the body's ability to maintain balanced metabolism.

Enzymes are protein molecules used by the body to perform all of its chemical actions and reactions. The body manufactures several thousands enzymes. Among them are the digestive enzymes produced by the stomach, pancreas, small intestine, and the salivary glands of the mouth. Their energy-producing properties are responsible for not only the digestion of nutrients, but their absorption, transportation, metabolism, and elimination as well.

Enzymes were first used in 1902 by Scottish scientist John Beard, who used pancreatic enzymes to treat cancer. German researchers used the therapy in treatment of multiple sclerosis, cancer, and some viral infections. Modern enzyme therapy is based on the work of Edward Howell in the 1920s and 1930s. Howell proposed that enzymes Page 947  |  Top of Articlefrom foods work in the stomach to predigest food. He advocated the consumption of large amounts of plant enzymes, theorizing that if the body had to use less of its own enzymes for digestion, it could store them for maintaining metabolic harmony. Four categories of plant enzymes are helpful in predigestion: protease, amylase, lipase, and cellulase. Cellulase is particularly helpful because the body is unable to produce it.

Animal enzymes, such as pepsin extracted from the stomach of pigs, work more effectively in the duodenum. They are typically used for the treatment of nondigestive ailments.

The seven categories of food enzymes and their activities:

Enzyme theory generated further interest as the human diet became more dependent on processed and cooked foods. Enzymes are extremely sensitive to heat, and temperatures above 118°F (48°C) destroy them. Modern processes of pasteurization, canning, and micro-waving are particularly harmful to the enzymes in food.

In traditional medicine, enzyme supplements are often prescribed for patients suffering from disorders that affect the digestive process, such as cystic fibrosis, Gaucher disease, diabetes, and celiac disease. A program of enzyme supplementation is rarely recommended for healthy patients. However, proponents of enzyme therapy believe that such a program is beneficial for everyone. They point to the ability of enzymes to purify the blood, strengthen the immune system, enhance mental capacity, cleanse the colon, and maintain proper pH balance in urine. They believe that by improving the digestive process, the body is better able to combat infection and disease.

Some evidence suggests pancreatic enzymes derived from animal sources are helpful in cancer treatment. These enzymes may be able to dissolve the coating on cancer cells to make it easier for the immune system to attack the cancer cells. Although as of 2019 no studies have confirmed successful results of enzyme therapy in cancer treatment, some small-scale European studies have suggested that the therapy, in conjunction with mainstream cancer treatments, can improve and possibly prolong the life of cancer patients.

A partial list of the wide variety of complaints and illnesses that can be treated by enzyme therapy includes:

Evidence to support enzyme therapy for treatment of these conditions tends to be sparse or lacking, however, and is mainly anecdotal.

Enzyme supplements are extracted from plants such as pineapple and papaya and from the organs of cows and pigs. The supplements are typically given in tablet or capsule form. Pancreatic enzymes may also be given by injection. The dosage varies with the condition being treated. For nondigestive ailments, the supplements are taken in the hour before meals so that they can be quickly absorbed into the blood. For digestive ailments, Page 948  |  Top of Articlethe supplements are taken immediately before meals accompanied by a large glass of fluids. Pancreatic enzymes may be accompanied by doses of vitamin A.

Enzyme preparations are available in a variety of forms, including tablets, capsules, liquid formations, and topical ointments. Treatments approved by the US Food and Drug Administration (FDA) are typically in infusion form.

People with allergies to beef, pork, pineapples, and papaya may suffer allergic reactions to enzyme supplements. Tablets are often coated to prevent them from breaking down in the stomach and usually should not be chewed or crushed. People who have difficulty swallowing pills can request enzyme supplements in capsule form. The capsules can then be opened and the contents sprinkled onto soft foods such as applesauce.

Side effects associated with enzyme therapy include heartburn, nausea and vomiting, diarrhea, bloating, gas, and acne. According to the principles of therapy, these are temporary cleansing symptoms. Drinking eight to ten glasses of water daily and getting regular exercise can reduce the discomfort of these side effects. Individuals may also experience an increase in bowel movements, perhaps one or two per day. This side effect is also considered a positive effect.

Individuals should always check with a doctor before using enzymes. Plant enzymes are safe for pregnant women, but animal enzymes should be avoided during pregnancy. In rare cases, extremely high doses of enzymes can result in a buildup of uric acid in the blood or urine and can cause a breakdown of proteins.

FDA-approved formulations may have infusion-associated side effects, including chills, tachycardia, skin reactions, nausea, malaise, joint pain, dizziness, and others.

In the United States, the FDA has classified enzymes as a food. Therefore, they can be purchased without a prescription. However, insurance coverage is usually dependent on the therapy resulting from a doctor's orders.

In July 2010, the FDA approved velaglucerase alfa for injection (VPRIV) for treatment of children and adults with Gaucher disease, which is a rare genetic disorder that affects approximately 1 in 50,000–100,000 people. VPRIV may be used in long-term enzyme replacement therapy for type 1 Gaucher disease. In March 2012, the FDA approved Ultresa (pancrelipase) for use in patients with cystic fibrosis who need pancreatic enzyme replacement in order to absorb needed vitamins and nutrients.

As of 2019, studies involving the use of enzyme therapy were still limited and general treatment with enzymes was controversial among traditional physicians and some alternative healers.

There is no specific training or certification required for practicing enzyme therapy.