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Until recently, Menadione Sodium Bisulfite Complex was only one of many obscure ingredients listed on some cat food labels. You may also have seen it as "Vitamin K3" among other names. The use of Menadione, as I'll refer to it here, has become increasingly controversial as a cat food ingredient. One of Menadione's biggest opponents is Susan Thixon, founder of PetSumer Report Online. She writes for Big Cat Rescue that Menadione has carcinogenic effects and "is toxic to kidneys, lungs, liver, mucous membranes." The FDA takes a less cautious approach and has no present restrictions on the use of Menadione in pet foods, if you can read through its obscure language in this PDF file.

I've noticed Menadione listed in the ingredients of some of the premium foods on my current lists. Since the jury is still out on Menadione, I will not remove those foods from the lists, but will note the inclusion of Menadione in their descriptions, and in other foods, going forward. Read more on Menadione.


April 10, 2009 at 10:35 am
(1) E says:

I don’t understand how it is carcinogenic. Does she have research to back up that it is the synthetic vitamin K that is the problem? Does that mean that the synthesizing is the problem.
Sigh. I may just go back to 9-Lives and forget about it.

April 10, 2009 at 12:22 pm
(2) Franny Syufy says:

Here’s her article, E. There’s a link half-way down the article to a Science Lab article

>>>I may just go back to 9-Lives and forget about it.<<<

I don’t know about you, E, but I’d much prefer a premium food with *one* controversial ingredient than a “supermarket” food with multiple very undesirable ingredients AND that controversial ingredient.

9-Lives Ingredients:

*poultry by-product meal, **corn gluten meal, soybean meal, whole wheat, *meat & bone meal, *animal fat (preserved with mixed tocopherols), salmon, chicken, beef, *animal digest, salt, phosphoric acid, choline chloride, titanium dioxide, potassium chloride, vitamins (vitamin E supplement, niacin supplement, d-calcium pantothenate, thiamine mononitrate, riboflavin supplement, vitamin A supplement, pyridoxine hydrochloride, *menadione sodium bisulfite complex*, folic acid, biotin, vitamin B12 supplement, vitamin D3 supplement), taurine, minerals (ferrous sulfate, zinc oxide, manganous oxide, copper sulfate, calcium iodate, sodium selenite), red 40, yellow 5, yellow 6, potassium sorbate (used as a preservative), *BHA (used as a preservative), blue 1, rosemary extract.

*Ingredients to Avoid
**Undesirable ingredients

October 14, 2009 at 2:20 am
(3) Diana says:

Why give your animals something that is toxic to humans?? The FDA has banned synthetic vitamin-K in OTC products b/c it is so dangerous. Europe has banned it also. If you want your pet to get Vit-K then look for foods w/ green leafy veggies in it. Dogs can eat spinach, bananas, & broccoli for example. So you can even supplement store pet food w/ veggies. I think the best question to all pet owners & humans regarding controversial ingredients -IS WHY TAKE THE CHANCE? There is real good quality food so why not eat that?!

January 12, 2010 at 8:03 am
(4) Sonya says:

Hi Franny,

I agree with you on the Menadione Sodium Bisulfite Complex. It is actually toxic in long-term use. Mendione is in fact acknowledged as toxic enough to be used in testing for Lethal Dose (LD50) of toxic substances by comparison. Menadione derivatives are used to induce toxicity experimentally so as to do research on how to undo it.

I do not quite agree on the ingredients you marked as bad in 9-Lives: Poultry by-product meal (although as # 1 ingredient not so good), meat (nothing wrong with ground up meat unless it is the “wrong” animal) & bone meal (source of calcium and other minerals, mouse bones are eaten, too) and animal digest (predigested stuff a cat usually gets from a mouse stomach) are not the worst ingredients in that food. It is bad for other reasons: One of the sources of protein is SOY BEAN MEAL, which has nothing to do with proper cat nutrition. It is a hazard for the kidneys waiting to happen since it has wrong pH. Beef is not the most suitable meat for cats. I agree on the animal fat being bad (chicken fat would be good, everything else is potentially bad). Red 40, yellow 5, yellow 6, blue 1 (<- all potentially allergenic), rosemary extract (cheap and health damaging preservative for cats) can cause all kinds of allergies. And BHA is a potential carcinogenic.

January 15, 2010 at 5:29 pm
(5) Gary says:

No one at this time has posted an actual study that backs up the statements made. All information so far refers back to unsubstantiated websites with referalls to other unsubstantiated websites.
The origin of the information comes from a report in Europe that the Author admits having trouble in translating.

October 7, 2011 at 1:07 pm
(6) Ryan says:


Study from the Linus Pauling Institute at Oregon State University reporting Menadione toxicity.

March 29, 2010 at 12:42 am
(7) B Dawson says:

As near as I can tell, the only concrete info comes from the Material Safety Data Sheets which are issued for the concentrated product, not the small amounts that wind up in pet food. Please be careful when extrapolating this information.

If any of you objecting to Menadione Sodium Bisulfate in food drink tap water, you better think twice. The flouride you are drinking in the water, in its concentrated form, must be stored in secure buildings that can only be entered with respirators and safety clothing. The HF is a strong acid that will burn thru your skin and poison you; one lung full will put you in the hospital. Yes, I worked as a water/wastewater chemist for a number of years and I don’t drink unfiltered tap water.

I’m still looking for some studies that link Menadione with health problems in pets. Anyone have any links to share?

BTW Sonya:

“…animal digest (predigested stuff a cat usually gets from a mouse stomach)…”

“Animal digests” in pet food are NOT the same as “digested food” from a prey animal’s stomach except to the extent they have both been exposed to a chemical agent that breaks down organic matter into smaller pieces. The commercial “digestion” process uses very poor quality body parts and harsh chemicals to do the job.

Feed your pets to the best of your ability folks, but realize there are no perfect solutions. I advocate raw diets whenever practicable.

March 29, 2010 at 12:38 pm
(8) Franny Syufy says:

This is for B. Dawson:

Thank you for your expert comments. I can’t really disagree with anything you’ve posted.

When I was a child, we lived in Lubbock, TX for awhile. My cousins there all had brown horizontal ridges on their teeth. I learned much later that it was caused by the very large amount of “natural” flouride in the wells that supplied the town’s drinking water.

Since today we can’t control the flouride that many municipalities add to water, I’ve had a longtime policy of using only filtered tap water.

December 8, 2011 at 9:39 am
(9) anon says:

I bought BFF and it seems to have this same ingredient. I have a cat that was recently diagnosed with CRF and there’s no way I’m feeding him something with the potential to hurt his kidneys. He’s getting Hills k/d from here on out.

May 28, 2012 at 2:19 am
(10) Bryon says:

Menadione is a synthetic vitamin K. It is known to cure late stage cancer and from experience with dogs it works wonders. It cures osteoporosis and bleeding disorders along with cavities and skin disorders. The toxic reports are an attempt to protect the profits of big pharma because vitamin K3 cannot be patented. (and it is too cheap for them to realize huge profits from cancer therapy).

April 7, 2013 at 5:09 pm
(11) MNixon says:

Well, you may say there isn’t enough evidence that Menadione Sodium Bisulfate is harmful to cats, but our perfectly healthy, lively 8 year old cat just developed acute kidney failure IN A MATTER OF WEEKS, after switching his diet over to all Weruva products. Previously we fed him occasional Weruva, plus Stella & Chewys. For various reasons, we recently switched to feeding him an all Weruva diet, with three kinds of Weruva; Mack n Jack, Asian Fusion, Polynesian BBQ – his health diminished very rapidly, and after three weeks he had kidney failure. Nothing else in his diet or life had changed. As I said, he was a completely healthy cat before we fed him the all Weruva diet.

The Weruva products we fed him ALL contained Menadione Sodium Bisulfate / “Vitamin” K3. Two of the products also contained very HIGH levels of Phosphorus – more than any other products on the market. Also, they were all fish products, which we now know aren’t good for cats. Those three factors combined? Our family member and close friend, our kitty of 8 years, may not make it through this weekend (he is on emergency IV in hospital). If he does survive, he’ll probably only live a few more months. (He had blood CREA levels of 11.1mg.)

If you need more proof – around the same time that we started feeding our cat Weruva, good friends of ours also decided they liked the product. Our *vet* recommended it! This weekend, after taking our cat to hospital, we contacted our friends, intending to warn them about the Weruva. Too late. Their cat, they told us, their cat had stopped eating recently too, and they’d just learned he had developed liver disease. Menadione Sodium Bisulfate is toxic to many different organs of the body. These are two sad stories to illustrate this.

THANKS Weruva. Do you really think its worth the risk to cats’ lives to save a little bit of money with this cheap additive?

February 5, 2014 at 2:59 pm
(12) insanecatlady says:

You can not compare cat food and dog food anyway a cat would can not survive on dog food and some of the ingredients in dog food are actually not that good for cats some even being poisonous to cats. A recent televised report on the dog food trade actually came up inconclusive to weather commercial or raw or even veg diet was better.
Going to the vet is no help either as most vets are in the pocket of the large commercial pet food industries. Until we the consumers start really kicking up a fuss the large companies will keep putting potentially harmful and indigestible profit making items into their food. Its about time we as pet lovers started demanding to KNOW what we are feeding our pets in terms we can all understand. Until then we are getting ripped off every which way we go
Unfortunately i have not seen one for cats but the show is worth a watch even if you do only have cats. Hope this can help people
The dog food programme

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