According to veterinarians across the country, nutraceuticals—loosely defined as products added to a pet’s diet to either treat an existing condition or maximize overall health—are continuing to grow in popularity.
Donna Raditic, DVM, CVA, who works in integrative medicine at the University of Tennessee College of Veterinary Medecine in Knoxville, said veterinary nutraceuticals started with alternative treatments for skin and allergic skin disease, with osteoarthritis remedies coming soon after.
Supplements for liver function followed, Dr. Raditic said, and now the focus seems to be on renal issues such as urinary tract infections, with more growth on the horizon.
"Now it is an explosion for just about everything,” she said. "Neoplasia, immune diseases, gastrointestinal—you name it, it is out there.”
While pet owners appear to be enthusiastic about nutraceuticals, veterinarians’ opinions about their efficacy differ. Some veterinarians—such as Paula Fisher, DVM, who runs an independent holistic practice in North Canton, Ohio—have embraced nutraceuticals wholeheartedly.
"I use nutraceuticals for every single animal that walks through the door,” Dr. Fisher said. "The majority of animals benefit greatly from this source of nutrition.
"Standard Process products provide nutrition by way of vitamins and minerals and glandulars. They are all food-based products, which in general are safer because they can be processed like a food.
"I am a strong believer in whole-food supplements rather than vitamin or single-ingredient supplements,” she said.
Others—like Brennen McKenzie, M.A., VMD, who is president of the Evidence-Based Veterinary Medicine Association and is in general small animal practice at Adobe Animal Hospital in Los Altos, Calif., are more skeptical. Dr. McKenzie acknowledged the apparent utility of some nutraceuticals for specific purposes in individual cases, but also expressed concern about the evidence base for others.
"Many supplements are marketed for pets, and there is almost never any scientific research of adequate quantity or quality available to truly evaluate whether these are safe or effective,” McKenzie said.
"There is a common misconception that supplements are ‘good for you’ in a general way and that it doesn’t matter much what you take them for. However, the reality is that if a substance you put into a complex living organism has any effect at all, it is likely to have a variety of effects, some desirable and some undesirable.
"In other words, if there are no side effects, the product probably isn’t doing anything. And if a supplement really does have a benefit, it probably also has risks.”
Despite her similar concerns about the availability and quality of research on nutraceuticals, Raditic said she recommends a number of the more common ones to her clients.
"Some [nutraceuticals] are fairly mainstream, like omega-3 fish oils, glucosamine, milk thistle,” she said.
"Companies such as Nutramax have done a great job getting these products into mainstream, conventional therapy. We use all types, but we select products and companies and have very specific goals for that patient when we put a patient on a nutraceutical. We work hard to keep owners and vets from spending lots of money on products that are not even logical.”
Cailin Heinze, VMD, Dipl. ACVN, a member of the faculty at Cummings School of Veterinary Medicine at Tufts University in North Grafton, Mass., and a veterinary nutritionist at Cummings’ on-campus clinics, expressed concern about the ways clients use nutraceuticals.
"It’s not uncommon that we’ll have a client come in that’s feeding anywhere from two to four nutraceutical products, sometimes with ingredients that could interact with drugs, or with overlapping ingredients,” she said.
Raditic had a similar concern.
"I spend more time investigating these products and [sometimes have] owners stop them as there is concern with ‘too much,’ or some of the other components make the patient at risk for a nutrient excess.”
Communicating with Clients
Given the relatively light regulation for nutraceuticals compared to FDA-approved drugs, veterinarians interviewed for this article said they communicate carefully with their clients to manage expectations and provide adequate information to ensure they provide the opportunity for truly informed consent.
Dr. Heinze described a categorical breakdown she uses to discuss nutraceuticals with clients: those that are proven safe and proven efficacious; those with proven or presumed safety but unknown efficacy; and those with unknown safety and unknown efficacy.
Heinze said that there are very few products in the first category, with fish oil being one, and she emphasized that it is important to research both the product and its manufacturer before concluding that any product belongs in that category.
Most nutraceuticals, she said, fall into the second category.
Products with proprietary blends that are not listed on their labels make up the third category, she said, because without full information, veterinarians are unable to evaluate them.
What to look for
Brennen McKenzie, VMD, president of the Evidence-Based Veterinary Medicine Association, recommends that clinicians ask themselves these questions before recommending any particular supplement:
• Is there a plausible theoretical mechanism that suggests it could work?
McKenzie described a similar categorical approach.
"If the evidence is pretty strong against any benefit, as for glucosamine, I am honest with clients about that, and I don’t recommend the supplement,” he said.
"If the evidence is positive or at least encouraging, as for fish oils for allergic skin disease or arthritis, I explain that to my clients and tell them I think trying the supplement is reasonable, though we cannot be certain it will have a meaningful benefit.
"And if the evidence is very weak or entirely anecdotal, as is the case for most veterinary supplements, then I tell clients we honestly don’t know what the benefits or risks are and that use of the product is essentially a roll of the dice.”
While controversy remains regarding nutraceuticals, it is clear that a number of them are in wide use both among veterinarians and pet owners. Research examining their efficacy, benefits and risks will likely continue in the coming years.
Jennifer Larsen, DVM, Ph.D., Dipl. ACVN, who is an assistant professor of clinical nutrition at the Veterinary Medical Teaching Hospital at the University of California, Davis, and provides clinical nutritional consulting through the VMTH Nutrition Support Service at the university, shared her observations of a few products that seem to be up-and-coming.
"I think compounds that might be useful for cognitive dysfunction such as caprylic acid and those with promise for cancer prevention and other effects such as resveratrol will continue to be actively studied in the near future,” she said.