Nutritional Supplements: What You Need to Know

Supplements and natural remedies are an exciting new/old approach to medicine. Separate the myths from the facts and learn to identify products that can benefit your best friend.


Do supplements work?

For simplicity, I am going to lump herbal remedies, natural products, vitamins, and minerals together under “supplements.” These can be roughly thrown into three buckets:

Bucket #1: The holy grail of supplements. Unbiased, scientific research in the form of randomized, controlled clinical trials has shown that this supplement has a beneficial effect. Few have been subjected to this level of scrutiny, and of those that have, many have only been studied in humans.

Bucket #2: Seems to work, but there isn’t strong research to support its use. However, it appears to be safe. There are many, many supplements that have tons of anecdotal evidence supporting them, but that have not been validated scientifically. This doesn’t necessarily mean they don’t work. In many circumstances, some may be worth a try.

Bucket #3: Research or clinical experience has demonstrated this product to be ineffective or even dangerous. Yes, there are many out there that are nonetheless still sold to unsuspecting consumers.


Of course, you want to favor Bucket #1 over Bucket #2, and to avoid Bucket #3 altogether. How do you do that? My favorite free resource for the lay public is on the Memorial Sloan Kettering Cancer Center’s website. You can search for the product of interest to uncover a wealth of information, including links to related published studies. Versions targeted to consumers and health professionals are both available. They even have an app! The biggest drawback is that the information only applies to human patients. You should consult with a veterinarian trained in natural medicine, who has examined your pet, before giving any supplement.

Why is there so little research into supplements? It seems that if a product has been used for thousands of years, it would have been tested by now. The primary reason is probably economic. The main driver of medical research is money provided by pharmaceutical companies. Testing and developing a new drug is expensive, and if the product cannot be patented, there’s no incentive to do the research. Other sources of funding (government, academic institutions) have made supplements a low priority, but that is beginning to change. In the meantime, we must be extra judicious when choosing these products.


Buyer Beware

You’ve found something that has evidence supporting its use (such as fish oil for dogs with arthritis) and you want to try it, but now you have to choose a brand or product. Here’s where the difference between how supplements and pharmaceuticals are treated by the government becomes important. When a new pharmaceutical is developed, the FDA will not approve it for sale in the U.S. until rigorous clinical trials have demonstrated its safety and effectiveness in real patients. This is not a bulletproof process – sometimes when moving from trials to widespread use in thousands or millions of patients, unforeseen adverse reactions become apparent. Still, the stringent FDA requirements prevent a LOT of ineffective or harmful would-be drugs from ever reaching the market.

Since the passage of the Dietary Supplement Health and Education Act of 1994, supplements have been subjected to a different set of regulations. Effectiveness does NOT need to be proven to market and sell a so-called nutritional product. The manufacturer and distributor of the product are held responsible for testing and ensuring the safety of the supplement before it is released to the market. The FDA can ban products shown to harm consumers, or those that are mislabeled or otherwise fraudulent.  Any product sold as a supplement (as opposed to a pharmaceutical) must not make certain health claims (e.g. “treats foot rot”). What can and cannot be claimed on a label is too complicated to discuss here, but you can learn more at the FDA’s website. The general rule of thumb is that the label cannot claim to treat or manage a particular health condition.

A serious problem in the supplement industry is that there are a lot of shady players making big promises out there. These companies may cut corners in manufacturing, quality control, and safety. Oversight by the government is not as stringent as it is for pharmaceuticals, although the situation is better in the U.S. than in some other parts of the world. A voluntary program administered by the National Animal Supplement Council audits manufacturers for proper quality control and labeling procedures. Companies that successfully complete the program earn the right to display the NASC seal on their product.

Your best bet is to use a product recommended by your veterinarian. If you choose to go looking for one of your own, here’s a guide to evaluating a product off the shelf:

  1. Is it a major/recognizable brand?
  2. Are the contents clearly indicated on the label? This should be a specific quantity with numbers and units (e.g. “Each capsule contains 1000 mg of EPA”).
  3. Is the label free of any sketchy claims? Remember, the FDA forbids certain health claims to be made on supplements.
  4. Are dosing/administration recommendations included? (IMPORTANT: These cannot be extrapolated by weight to your pet if it is a product labeled for humans. Ask your vet!)
  5. Is there a lot number or serial number on the bottle, and is there an expiration date?
  6. Does it state where the product is manufactured? If not, avoid. If so, the U.S.A. is preferable. Products from certain countries have been plagued with issues such as inaccurate ingredient claims and contamination with pharmaceuticals, heavy metals, pesticides, or even endangered species. If you wouldn’t give your dog jerky treats made in China, you shouldn’t give them herbal supplements made in China, either.
  7. Is there contact information for the manufacturer or distributor?

You should be able to answer “Yes” to all of the above. If not, move on.

What else should you know?

  • Just like pharmaceutical agents, supplements can have side effects or cause adverse reactions
  • Some supplements interact with drugs (making them less effective or more toxic) or other supplements

Finally, just as with drugs, remember that our animal friends are not just little people. They metabolize and process certain substances very differently than we do. If it’s safe and effective for humans, you cannot necessarily assume the same is true for animals. We’ve previously discussed the dangers of giving over-the-counter medications to pets without consulting your veterinarian – you should heed that same advice when it comes to supplements.

Natural medicine has great potential to improve animal health and wellbeing, and more veterinarians than ever are becoming skilled in these complementary therapies. Just as with conventional medicine, we need to be savvy consumers to reap the benefits while keeping our animal companions safe.


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