The ingredient Menadione Sodium Bisulfite Complex is commonly used in pet foods as a source of vitamin K…but…the ingredient is ONLY legally approved for use in poultry feed.
We asked the FDA and AAFCO why this ingredient is used in pet foods but not approved for pet food.
Although it took the agency 2 months to respond, the FDA stated:
“Thank you for contacting FDA’s Center for Veterinary Medicine (CVM). In your email from January 26, 2026, you inquired about FDA taking action on cat foods that include menadione sodium bisulfite. You also mention that the ingredient is only approved for poultry feed.
Menadione sodium bisulfite complex (MSBC) and menadione are prior sanctioned as sources of vitamin K activity in poultry feeds at 2-4 g/ton. However, the FDA has not initiated regulatory action against other animal foods, including pet food, that contain menadione or MSBC as sources of vitamin K activity. FDA is unaware of any apparent animal safety concerns if these ingredients are used in accordance with good manufacturing processes.
More information regarding vitamin K can be found at: Vitamin K Substances and Animal Feed | FDA.
In addition, in 2021, AAFCO convened a panel of experts to provide policy recommendations for the use of Menadione Sodium Bisulfite Complex (MSBC) for intended uses beyond poultry feed. The panel recommended that MSBC may be used as a safe and suitable source of Vitamin K activity in the food for all animals in the United States in accordance with good manufacturing and feeding practices.”
AAFCO responded much more promptly, stating:
“The short answer to your question is regulatory discretion by many state regulators, but the safety rationale behind that decision is laid out beginning on p.340 of the OP in Recommendations for Use of MSBC in Animal Feed.”
So…the ingredient Menadione Sodium Bisulfite Complex is NOT approved for use in pet food, but everyone has agreed to not enforce law because they believe the ingredient is safe to include in pet food.
Why not just change the law and approve the ingredient for use in pet food?
In 2021, AAFCO formed an “expert panel” to “provide policy recommendations for the use of Menadione Sodium Bisulfite Complex (MSBC) for intended uses beyond poultry feed.”
The expert panel provided AAFCO a detailed report that includes historical use of the ingredient, safety studies, and more. “The panel recommended that Menadione Sodium Bisulfite Complex may be used as a safe and suitable source of Vitamin K activity in the food for all animals in the United States in accordance with good manufacturing and feeding practices.”
But again…why go to the effort of forming an expert panel, compiling research, preparing a detailed report…and still not officially approve the ingredient for use in pet food? The process to change the legal definition of Menadione Sodium Bisulfite Complex to include use in dog food, cat food and other species would take just a few minutes (ten minutes at most) at an AAFCO meeting. Why are they not doing this last simple step? Instead relying on enforcement discretion (ignoring law)?
Personal opinion: Typically, in a case like this when the ingredient is already approved for one species and the only issue left to discuss is – is it safe for additional species, AAFCO does exactly what it did in this instance – form an expert panel. But in every other instance to my knowledge, after the expert panel provides their opinion – AAFCO brings the discussion back to a meeting and adds their approval for additional species or denies their approval for additional species. AAFCO typically finishes the process, makes it official in regulation.
But in this case, they did not. Five years after the expert panel declared the ingredients safe…no action by regulatory as been taken to legally approve the ingredient for use in pet food. It does not make sense.
The answer might be as simple as they just haven’t gotten around to approving Menadione Sodium Bisulfite Complex in pet food. But…it has been five years since the expert committee declared the ingredient safe for use in pet food.
It’s a puzzle.
Susan Thixton
Pet Food Safety Advocate
Author Buyer Beware, Co-Author Dinner PAWsible
TruthaboutPetFood.com
Association for Truth in Pet Food
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Teresa Johnson
March 26, 2026 at 1:34 pm
Hmmmmm, could it be there is underlying (unspoken) knowledge and/or concerns that MSBC is not really as safe as we are being led to believe? OR is it that they (FDA and AAFCO) know manufacturing processes are far from safe as shown in the many recalls of products due to misdoing vitamins and minerals alone, let alone acknowledged contaminations such as salmonella, listeria, molds?
Personal opinion: AAFCO is a fox guarding a hen house. FDA simply can’t be bothered with safety concerns regarding animals in general.
Carole
March 26, 2026 at 3:57 pm
Sheesh! It sure sounds like the old hack phrase “I’m from the government and I’m here to help you!”
Thanks bureaucrats, you don’t seem to be much help.
🐶 🐈
Jean Palmer
March 26, 2026 at 4:00 pm
Thank you Susan for all the work you do for the animals. I shared your column on X.
Sandy M.
March 26, 2026 at 4:23 pm
There is a clear “corporate culture” problem going on between the FDA and The AAFCO. They just do what they want “everyone has agreed to not enforce law”. Why do laws exist?! This is disgusting display of the wild wild west nature of the pet food manufacturing industry. Sure, this is a little issue, but it shines a light on the bigger problem.
Carol Chakeropulos
March 26, 2026 at 6:04 pm
I never heard of this. We all know the answer: They just don’t care.
It is very upsetting and frustrating. Thank you, Susan, for all you do, for all you try so hard to do.
Carol
Peter
March 31, 2026 at 6:58 am
It seems fair to conclude why FDA has not done what they should do…because the FDA is in “regulatory capture,” beholden to the business that it is legally responsible to enforce rules for.