This is very discouraging; the ONLY AAFCO approved supplement of Vitamin K in dog foods and cat foods is the supplement Menadione Sodium Bisulfite Complex.  No natural Vitamin K supplement is approved; only menadione sodium bisulfite which is linked to serious illness in German research.

An observant Pet Parent emailed me regarding an ingredient change in a Innova pet food.  She shared that the Innova pet food label had changed to including Menadione Sodium Bisulfite.  I called Innova asking about the change, and was told that AAFCO requires Menadione to be the vitamin K supplement.  In a state of shock, I emailed AAFCO for clarification.

Before we get to the worse news, here is some information about Menadione – vitamin K3…
“Menadione, also known as vitamin K3, is a synthetic version of vitamin K. The natural occuring compounds are vitamin K1 (Phylloquinone, from plant sources) and Vitamin K2 (Menaquinone, synthesized by bacteria in the digestive tract and absorbed by the body). Technically menadione isn’t even a vitamin, but a precursor that is converted in the body after ingestion. Natural vitamin K is fat soluble, while menadione derivatives (pure menadione can not be processed) are water soluble and bypass the natural pathway of utilization by the body.”

And, based on German research…some of the negative effects of menadione are…
•    causes cytotoxicity in liver cells
•    damages the natural vitamin K cycle
•    causes hemolytic anemia and hyperbilirubinemia, not just linked to large doses
•    is directly toxic in high doses (vomiting, albuminuria), unlike natural vitamin K
•    has never been researched or specifically approved for long term use, such as in pet food
•    FDA has banned synthetic vitamin K from over-the-counter supplements because of its high toxicity

The material safety data sheet from states the following on Menadione sodium bisulfite…

“Potential Chronic Health Effects:  CARCINOGENIC EFFECTS: 3 (Not classifiable for human.) by IARC. MUTAGENIC EFFECTS: Mutagenic for mammalian somatic cells. TERATOGENIC EFFECTS: Not available. DEVELOPMENTAL TOXICITY: Not available. The substance is toxic to kidneys, lungs, liver, mucous membranes. Repeated or prolonged exposure to the substance can produce target organs

And now for the worse news, AAFCO (Association of American Feed Control Officials) Pet Food Committee Chair Liz Higgins provided the following response to my Menadione Sodium Bisulfite question…

“Menadione sodium bisulfite complex is the only  acceptable source of Vitamin K in pet foods.  At this time, no other sources of Vitamin K are allowed in pet food including natural Vitamin K and K1 (phylloquinone).  If you have additional questions regarding vitamins, please contact Ali Kashani, who is AAFCO’s Vitamin Investigator.
I hope this answers your question,


Liz Higgins

Still in disbelief that AAFCO would not/has not approved a natural source of vitamin K supplement, I followed Ms. Higgins suggestion and emailed Ali Kashani (side note:  I met Mr. Kashani at the January AAFCO meeting and found him to be very helpful).

My email to Ali Kashani…

Hello Ali,
I met you at the January AAFCO meeting (hope you remember).  Liz Higgins directed me to email you – in that you are AAFCO’s Vitamin Investigator.  My question to AAFCO was regarding Menadione sodium bisulfite.  Liz replied that this is the only acceptable source of vitamin K in pet foods.  Why is that?  She stated “no other sources of Vitamin K are allowed in pet food including natural Vitamin K”…is this correct?  Does this mean that if a pet food – as example – contains spinach which provides all the necessary vitamin K to meet AAFCO requirements it wouldn’t be ‘an approved source’ of vitamin K?

I’m really hoping this is incorrect.  Menadione sodium bisulfite is considered by many experts as a risky source of vitamin K for dogs and cats.  Again, I’m hoping what Liz sent me is incorrect.  Please let me know.
Susan Thixton

His response (very prompt in responding too!)…
“Good morning Susan,

I certainly remember meeting you at the January AAFCO meeting and our brief discussion on the first and second days of the meeting.

In order for ingredients to be considered safe and effective for their intended use, data need to be submitted and reviewed, unless one of other conditions like generally recognized safe (GRAS) and or prior history of safety use have been determined.  Menadione or Menadione sodium bisulfite complex has a GRAS status for use in poultry feed at 2 to 4 g per ton of feed (Federal Register 55:50777, December 10, 1990).  .  States and FDA have given low regulatory priority for use of the above vitamin as source of vitamin K in other species’ feeds including pet food.

I believe Liz’s reference was to pure sources of vitamin K.  If you have ingredients that contain natural sources of vitamin K in their composition, as long as the methods of analyses are legitimate and can be verified, I believe the manufacturer can list it in the guaranteed analysis section of the label, as long as they meet other requirements (units of the vitamin, etc.).

I hope the above explanation adequately addresses your questions.  Please let me know if I can provide any additional explanation.  Best Regards!  Ali”

So…pet foods that include a natural source of vitamin K such as spinach, are not required to add menadione (as long as required levels of vitamin K are met/guaranteed).  But, all others do.  What a shame.

Ali Kashani shared with me that menadione has GRAS (Generally Recognized as Safe) status and to his knowledge “data from other pure sources of vitamin K have not been submitted for review”.  This means that no pet food manufacturer – that does not use a food source of vitamin K (such as spinach) – has ever bothered to provide AAFCO with data on the safety of a natural vitamin K supplement for approved use in pet food.   No one has ever bothered; they just keep using a synthetic vitamin K without any regard to various German studies that show a real concern.

If your choice of pet food contains the ingredient Menadione Sodium Bisulfite Complex, please send that company an email and ask why they would use a synthetic vitamin instead of a natural vitamin supplement.  If they bother to respond, and tell you AAFCO’s only approved vitamin K is menadione, ask them to get off their duffs and request AAFCO to approve natural sources of vitamin K.

No natural option for vitamin K supplement in pet foods is ridiculous.  No pet food manufacturer ever bothering to provide this to pet parents is even worse.  Kudos to all pet foods that use a natural – food source vitamin K!

And by the way, the largest producer of pet food vitamins and minerals (including menadione) is China.