Antioxidants and their Use in Dog Food


PetMD Editorial

Published Oct. 21, 2011

The reason your dog’s food can stay on the store shelves, and then sit in your pantry for a while longer, is that the food is preserved with antioxidants and other necessary ingredients called preservatives. Antioxidants are substances that provide health benefits and prevent ingredients in the food from spoiling (oxidation). They are very important to keep your dog’s food tasting good and help maintain its nutrients.


Oxidation is the process that occurs when foods are exposed to oxygen. Naturally, over time the oxygen will cause a breakdown in the nutrients and fats in a food and cause everything from discoloration to rancidity. An antioxidant works to block or slow down the rate at which oxygen causes damage. Antioxidants are added to foods during processing to extend the shelf life of the final product.

The success of antioxidants in pet food depends on several conditions. Generally, antioxidants work better if they are added early in the production process. Another factor to consider is the combination of antioxidants used in the formula. Specific amounts and types of particular antioxidants work better together than others.

What do Antioxidants do?

There are numerous health benefits provided by antioxidants—aside from preserving pet food. Antioxidants also protect the body’s cells from damage and strengthen the immune system. Every day, the body is exposed to the destructive effects of free radicals, which are produced when cells are damaged due to the effects of oxidation. These free radicals are unstable and can cause even further cell damage if left unchecked.

This is where antioxidants come into play. Antioxidants slow down damage from free radicals and prevent further cell damage. They allow the immune system to function without interference from free radicals. This protection is important to prevent serious health issues from developing or worsening.

In young animals, antioxidants provide a boost to the developing immune system before vaccination has a chance to be effective. In older animals, oxidative injury to cells in the brain and organs may be slowed by antioxidants, providing a longer, healthier lifespan.

Where do Antioxidants come from?

There are two types of antioxidants commonly used in dog foods — natural and synthetic. Natural antioxidants include vitamins C, E, citric acid, and some herbal sources like rosemary. Vitamin C can be taken from common fruits and vegetables like cranberries, apples, tomatoes, blueberries, and more. Natural vitamin E is commonly listed as “mixed tocopherols” on the pet food ingredient list. Citric acids are taken from various citrus fruits like oranges, lemons, and limes.

Common synthetic antioxidants (those created in a laboratory) you may see on the label include BHA, BHT, and ethoxyquin. BHA and BHT are chemically similar to vitamin E and are often used in combination in dog foods because they work well together. They are both very stable at high temperatures.

Ethoxyquin has been controversial in the past, but it is currently allowed in pet foods at low levels that are considered safe by the U.S. Food and Drug Administration. This antioxidant is considered to be very effective and stable during processing, providing excellent preservative abilities with little concern about side effects at the recommended levels.

Choosing a Dog Food

If you are scanning the ingredients list on a dog food bag, keep in mind that pet food companies are required to list antioxidants and their common names. You will also see a notation that the ingredient is used as a preservative.

While natural antioxidants may be considered more “healthy,” you must realize that they may not last as long to preserve the final product. Dog foods that are made with natural preservatives will have a shorter shelf life than a pet food made with a combination of natural and synthetic antioxidants.

No matter which food you choose, be sure to check the date on the package to see when the food is considered to be best used before. Store it in a cool, dry place, preferably in an airtight container, out of the light. Once opened, a food preserved with only natural antioxidants will lose its freshness sooner, so you may wish to purchase smaller packages.

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