- Is the supplement filling an essential nutrient need?
Commercial pet foods labeled as “complete and balanced” provide all of the essential nutrients that are required for life (with the exception of water), and nothing is else except for water needs to be added to the diet. But, while the majority of companion dogs and cats will do equally well and live long, happy lives on a variety of different commercial pet foods (no matter what form or where you buy them), there are a few notable exceptions where “complete and balanced” for longevity may not be the same as optimal intake for health and wellness (I’m looking at you essential fatty acids and dietary fiber). General purpose vitamin/mineral/fatty acid supplements are not providing any magic fixes; they are simply filling in the difference between what the general population needs and what the individual needs. Depending on the ingredients they can be good sources of essential fatty acids, but have relatively low levels of all essential minerals and most vitamins to prevent nutrient toxicity when added on top of a commercial diet. This makes caregivers feel like you are helping their dog or cat without causing any harm (other than maybe to their wallet).
- Is it being used as a nutritional pharmaceutical (i.e., nutraceutical)?
It doesn’t matter if it is the long-chain fatty acids in fish oils that are given to dampen inflammation or glucosamine and chondroitin that may help support normal joint tissue. Caregivers give their dogs and cats many supplements and “natural” preparation to have a physiological effect when ingested (this is the same Oxford English Dictionary definition of a “drug” by the way) and not to fill an essential nutrient need. Despite being used to have a drug-like effect, after the passage of the Dietary Supplement Health and Education Act (DSHEA) in 1994, nutrient supplements and animal and plant products (other than tobacco specifically) were classified more like foods. Irrespective of regulation or manufacturing, the bottom line for me is that if you’re giving a supplement or natural preparation in order to change a disease state then you are giving it to have a drug effect. The regular pharmaceuticals industry has its roots in natural plant or animal compounds, the difference is whether the compounds are ingested in their natural states (wanted and unwanted compounds combined) or are taken as a purified and concentrated active ingredient. Kind of like the difference between chewing willow bark for your headache instead of taking 2 aspirin.
To Supplement or Not to Supplement, That is the Question.
- Supplements whether for pets or people are largely unregulated.
The passage of DSHEA was a coup for the supplement industry. Congress officially recognized that the supplement industry was an “integral part of the economy of the United States” and that the “Federal Government should not take any actions to impose unreasonable regulatory barriers limiting or slowing the flow of safe products and accurate information to consumers”. “Unreasonable regulatory barriers” like requiring supplement providers to prove safety, purity, or efficacy before launching a product on an unsuspecting marketplace; providing “accurate information” like marketing pamphlets made available in stores or on company sponsored websites. DSHEA does make allowances for FDA involvement if a product “presents a significant or unreasonable risk of illness or injury” or if a company makes an outright drug claim (like that it will cure cancer or obesity), but the “burden of proof” to prove that a supplement has been adulterated, contains harmful compounds, or that the company is engaged in illegal marketing practices was shifted to the United States government. So it isn’t until after a supplement has been widely sold and has caused harm to people or animals or the company is caught making therapeutic claims, that the FDA can become involved. This is almost the complete opposite of what is required for manufacturers of purified bioactive compounds (i.e., regular pharmaceuticals).
- Supplements are Big Business
Prior to the passage of DSHEA in 1994 supplements sales were a steady $4 billion a year, by 2009 the supplement industry was reporting annual sales of $20 billion, and by 2012 they were at a whopping $32 billion a year, and are showing no signs of slowing down. With a multibillion dollar a year prize, it is not hard to see why so many people are getting into the supplement game. Self-promoting media doctors (human medical and veterinary medical), fitness personalities, animal enthusiasts, celebrity chefs, dog trainers, and even people who are just looking for a get-rich-quick scheme are cashing in on the supplement craze. And why not? Without those silly “regulatory barriers” of having to prove quality or safety, the cost of entry is low and the potential payout is high. If you don’t think raw material providers and supplement marketers will try to cheat the system and make use of this loophole, just look at the recent case of supplement fraud in products sold in New York state or the Nature publication showing that most fish oil supplements sold for people in New Zealand contained significantly less long-chain omega-3 fatty acids that reported on the label. I am not one to buy into conspiracy theories normally, but considering that DSHEA was pushed through by a senator with substantial financial backing from the supplement industry I am a bit suspicious of the true motivations behind this act.
- Quality Control in the Supplement Industry is Self-Guided
I think of the current supplement industry much as I imagine the Wild West was once like. Some companies are doing a great job and are upstanding corporate citizens, while others are working just out of view of the enforcers and are focused on profits more than quality (or health). Good quality companies are screening raw materials, are conducting internal and external audits of products and manufacturing facilities, and participate in organizations like United States Pharmacopeia (USP; for human products) or National Animal Supplement Council (NASC; for animal products). The biggest different between USP and NASC is that while they both independently evaluate the manufacturing processes, labeling, and adverse event tracking for participating companies, only USP also performs independent testing of the products themselves to ensure purity and dosages, NASC does not. Both USP and NASC are also voluntary organizations and membership is not a requirement in order to sell products and makes millions (billions?) a year in supplement sales. Consumer Labs is another organization that conducts independent testing of mostly human (and sometimes veterinary) supplements and is a good resource for dog and cat caregivers.
I use certain supplements in practice on a regular basis. My general approach is that if I have clear scientific evidence that a particular supplement may help my patient (like is the case with essential fatty acids and animals with dermatitis on questionable diets), or if a supplement may or may not help but is not harmful (like glucosamine in animals with early, not advanced, joint disease – glucosamine has been shown not to work in advanced arthritis cases) then there is little cost to animal health or the family budget in adding these types of products in. But it is important for pet owners to know that supplements can cause harm and that they are basically unregulated pharmaceuticals. You need to know and trust your manufacturer. Supplements can benefit animal health and wellness, but they can also have no effect or make certain conditions worse. At the risk of sounding like a broke record (for those of you who know what a broken record sounds like), my hope that I can help you to become a more informed animal advocate for your furry family members for years to come.
Lisa Weeth, DVM, MRCVS, DACVN