Equine Supplements: Active vs. Inactive Ingredients

Q. I was recently looking at equine supplements and noticed that ingredients on the label are grouped into two categories: active and inactive, with amounts given for the active ingredients. I was surprised to see sodium chloride (salt) listed as an inactive ingredient, because I thought it was a common source of sodium for horses to help with hydration. Why would it be listed as an inactive ingredient?

A. This is a great question. Labeling requirements for supplements differ from those of feeds depending on their intended use. If the supplement’s aim is to affect the structure/function of the body in a manner other than food, then in the eyes of the regulatory bodies the product is a drug.

What Defines a Drug or Active Ingredient?

According to the U.S. Food and Drug Administration (FDA), two “drug” definitions exist in the United States:

  1. Those that are intended to cure, treat, prevent, or mitigate disease, and
  2. Those that affect structure and function.

The former is what most of us think of when we think of drugs. Drugs falling under this definition require strict trials conducted under FDA guidelines in prove they indeed do cure, treat, prevent, or mitigate disease.

Supplements fall under the second definition of a drug, which means they are meant to affect a horse’s structure or function. Under this banner, the manufacturer can make statements such as, “supports healthy inflammatory response” but can’t make statements that the product is “anti-inflammatory.” Saying that the product has anti-inflammatory properties would be making a treat, cure, prevent, and mitigate statement, which isn’t allowed.

Typically, within a supplement there are ingredients that are included specifically because they offer a therapeutic action. These are the active ingredients. Other ingredients don’t increase the affect the therapeutic action of the active ingredient, and these are inactive ingredients.

Inactive Ingredients

Inactive ingredients include preservatives such as ascorbic acid or vitamin E; flavoring agents both natural and artificial; binders such as clay; or compounds that help transport the active ingredients in to the body. Some common equine supplement inactive ingredients include alfalfa meal, vegetable oil, distillers’ grains, yeast, and grape pomace.

Typically, the amounts of the inactive ingredients aren’t provided because they aren’t playing roles directly relating to the purpose of the product. This practice also provides some protection for the proprietary nature of some supplements.

The National Animal Supplement Council’s (NASC) seal on a product packaging is a good indicator that the product you’re considering is correctly labeled and not making illegal claims, and that the contents conform to the listed ingredients . To display this seal on products, a company must successfully complete an independent quality audit, follow proper labelling guidelines, have comprehensive quality control and production procedures, participate in random product testing, and have their ingredients reviewed by the NASC scientific advisory committee, as well as several other measures. You can find a list of NASC-member manufacturers on the council’s website.

Salt: Active or Inactive?

If the purpose of the supplement you were looking at wasn’t hydration it’s likely that salt was included in the product as a flavoring and, therefore, is not an active ingredient. Additionally, keep in mind that an ingredient might be an active ingredient in one product and inactive in another. It all depends on the product’s purposes and the role of that ingredient within it.

Take-Home Message

Understanding some of what is and isn’t allowed on a supplement label can help you determine whether you’re looking at a quality product or, at least, that you’re about to do business with a company that knows the rules and is committed to following them.