The Controversy Over Menadione in Dog Food

Some call menadione a dog food necessity. Yet others reject it as a dangerous toxin.

So, what exactly is menadione? And why is it being used in some dog food recipes and not others?

Menadione is actually a vitamin. It’s the man-made version of an essential nutrient commonly known as vitamin K — or more precisely, vitamin K3.

Like all vitamins, menadione is an antioxidant that’s sometimes used as a preservative in dog food and dog treats.

K3 is just one of five known versions of vitamin K. The three most common types found in dog food include:

• Vitamin K1 – naturally found in green leafy vegetables
• Vitamin K2 – produced by bacteria living inside a dog’s gut
• Vitamin K3 – menadione, the man-made synthetic version

Vitamins K1 and K2 are considered natural and fat soluble. So, they’re chemically ready to be used by the body just as they are.

However, vitamin K3 is synthetic. And all forms of the chemical must first undergo the cellular process of alkylation before they can be used by the body.¹

So, What’s So Important
About Vitamin K?

Vitamin K is used by the liver to manufacture clotting factors, chemical compounds used by the body to help control bleeding.

So, how much vitamin K does a dog need?

Well, according to the National Academy of Science, not much. A dog needs very little vitamin K per serving to sustain life — only one part per million.²

And most of the vitamin needed by the animal is actually produced by bacteria living within the intestines.

What’s more, the vitamin is not even listed as a required dog food ingredient in the nutrient profiles established by the Association of American Feed Control Officials.³

Menadione — a Nutritional Necessity?

The controversy over menadione appears to be driven by two opposing views.

Supporters⁴ tend to see menadione as a necessary supplement that dog food manufacturers should include in their recipes. 

Dog food designers favor menadione because…

• Menadione has a longer shelf life than natural vitamin K
• Natural vitamin K may lose its potency during processing
• Intestinal disease can prevent gut bacteria from making the vitamin
• Not all manufacturers include green leafy vegetables in their recipes

Advocates also claim menadione should be considered safe because toxic levels are a thousand times greater than the recommended daily dose.

Or a Potential Toxin?

Critics⁵ see menadione as only a precursor to the vitamin’s more natural versions. They cite (mostly human) studies that make a number of unsettling claims. They worry that menadione can…

• Promote allergic reactions⁶
• Weaken the immune system
• Cause toxic reactions in liver cells⁷
• Induce hemolytic anemia (red blood cell toxicity)⁸

One company selling menadione warns its human buyers that menadione is “toxic to kidneys, lungs, liver, mucous membranes. Repeated or prolonged exposure to the substance can produce target organ damage.”⁹

Banned from
Human Supplements

According to a peer-reviewed article published in 2004 by the Linus Pauling Institute at Oregon State University:[1. Jane Higdon, PhD, Linus Pauling Institute, Oregon State University (2004); updated Victoria Drake, Ph.D.,
Linus Pauling Institute, Oregon State University (2008), peer-reviewed by Sarah Booth, Ph.D., Director, Vitamin K Research Program, Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, Vitamin K and the Newborn Reviewed by Dennis T. Costakos, M.D. F.A.A.P., Franciscan Skemp Healthcare-Mayo Health System, Mayo Medical School]

“Although allergic reaction is possible, there is no known toxicity associated with high doses of the phylloquinone (vitamin K1) or menaquinone (vitamin K2) forms of vitamin K¹⁰.

The same is not true for synthetic menadione (vitamin K3) and its derivatives.

Menadione can interfere with the function of glutathione, one of the body’s natural antioxidants, resulting in oxidative damage to cell membranes.

Menadione given by injection has induced liver toxicity, jaundice, and hemolytic anemia (due to the rupture of red blood cells) in infants¹¹; therefore, menadione is no longer used for treatment of vitamin K deficiency¹².

No tolerable upper level of intake has been established for vitamin K.”

The FDA has banned the use of menadione from over-the-counter supplements because large doses have been shown to cause these dangerous biological effects.¹³

The Case Against Menadione

Dr. Tom Cameron is a practicing veterinarian who has frequently voiced his concerns about the use of menadione in dog food.

In the following video, Dr. Cameron explains to Dr. Karen Becker why it’s safer and healthier to get vitamin K from food rather than menadione:

A Supplement
with Many Names

Unfortunately, it can be difficult to spot menadione in a dog food recipe. That’s because manufacturers frequently list the vitamin on a dog food label by one of its more cryptic chemical names:

• Vitamin K supplement
• Sodium metabisulfite
• Dimethylprimidinol sulfite
• Dimethylprimidinol sulfate
• Dimethylprimidinol bisulfate
• Menadione sodium bisulfite
• Menadione sodium bisulfate
• Menadione nicotinamide bisulfite
• Menadione dimethylprimidinol sulfite
• Menadione dimethylprimidinol sulfate
• Menadione dimethylprimidinol bisulfite

What’s more, you may even come across menadione disguised in seemingly innocent phrases like, “a source of vitamin K activity”.

The Bottom Line

When used in large amounts, menadione can be toxic.

However…

In small doses, like those used in commercial dog food, menadione is probably safe.

Yet unlike humans who tend to vary their diets with each meal, dogs are typically fed the same food on a continuous basis… for a lifetime.

And it’s that cumulative exposure to any controversial substance (like menadione) that tends to keep us up at night.

Since there are no AAFCO requirements to include vitamin K in any dog food…

You may wish to consider using diet rotation to lower the risk associated with endlessly feeding the same food… for a lifetime.