Matthew Cooper was living on Tums, Pepto-Bismol and Zantac and experiencing such a bad case of irritable bowel syndrome that he’d frequently have to abandon his wife and friends at restaurants midmeal. He had leg cramps, insomnia and chronic cases of fatigue and acid reflux. And then a friend turned him on to enzymes.

“Within a week, they changed my life,” said Cooper, a Miami chiropractor who runs the Enzyme Therapy Center there, one of a growing number of holistic medical practices dedicated to treating ailments like acne and sports injuries with enzymes.

The human body contains two kinds of enzymes: metabolic, which are found in every cell of the body and cause various chemical reactions, and digestive, which are released in the stomach and intestines and help break food down into usable nutrients. A third kind, food enzymes, are found in uncooked nuts, vegetables and fruit.

Raw-food advocates argue that, when eaten, food enzymes can help “predigest” nutrients.

This process, they claim, allows the body to use less of its own digestive enzymes and direct more energy to other functions, like organ repair and detoxification.

But the science behind this is dubious.

“Most people digest just fine,” said Dr. Donald Kirby, the director of the Center for Human Nutrition at Cleveland Clinic’s Digestive Disease Institute. “If you really need an enzyme supplement, then you have a medical condition and are probably under the care of a physician.”

Even so, raw-food diets and juice fasts, which have been championed by the actress Gwyneth Paltrow and the designer Donna Karan, have grown in popularity. But some find the rigid regimens, which can involve extensive shopping, preparation and luridly colored liquids, difficult to follow.

“That’s why enzymes come in handy,” said Robert Dagger, who owns High Vibe, a raw-food lifestyle store in New York that sells fresh-pressed juices, books and enzyme supplements in capsule form that Dagger formulates himself. “I’ll be out to dinner with people who aren’t healthy at all, and at the end of dinner they break out the enzymes,” he said.

The ingredient is also increasingly popular in mainstream beauty products, after years in the health-food aisle as an alternative to chemical exfoliants like glycolic and salicylic acids. Bromelain, an enzyme found in pineapple, and papain, which derives from papaya, are star ingredients in the clarifying facial mask and the night cream from Rx Skin Therapy. Next month, Natura Bisse, a Spanish luxury skin-care company, will start selling NB-Ceutical tolerance enzyme peel, an at-home peel with prickly pear and papaya enzymes geared toward sensitive skin.

Enzymes are also an important component in a few products from Immunocologie, a skin-care line introduced in 2010 and made with ingredients that are blended together via fermentation rather than heating. The company’s founder, Manzoor Jaffery, decided to start experimenting with enzymes because he’d read that they were added to animal feed to aid in digestion and thought the same idea could apply to the skin to help ingredients penetrate more deeply.

“The enzymes break down the amino acids into smaller molecules,” said Jaffery, a cosmetic chemist in Stratford, Conn., who holds multiple patents on skin-care ingredients.

Dr. Adam Kolker, a New York plastic surgeon, sells a line of products that includes a papaya face polish.

“For skin that is sensitive, enzymes are wonderful,” Kolker said. “Enzymes affect the peptide bonds — protein-based adhesions — between cells on the dead outer layer of skin cells. In time that bond will break; what the enzymes do is speed that reaction,” he explained, adding that as skin ages, that process slows down, making skin appear dull and flat.

Those who believe beauty starts from within might be curious about “The Beauty Detox Solution,” a diet guide released last spring by Kimberly Snyder, a nutritionist in Los Angeles and New York who advocates taking one digestive enzyme a day, plus before eating cooked food.

“It’s one of the few supplements I recommend,” said Snyder, whose celebrity following includes Drew Barrymore and Channing Tatum. “Enzymes are one of the secrets to longevity,” she said.

But Kirby, of the Center for Human Nutrition, cautioned: “Buyer beware.”

“For the average American looking to lose weight or improve their digestion, the odds of these enzyme supplements doing this are not high,” he said.