Menadione sodium bisulfate complex (MSBC) is a form of vitamin K. It’s found naturally in black walnut, but in pet food the synthetic form is used. Here’s what you need to know about menadione in dog food.
First, let’s look at vitamin K.
What Does Vitamin K Do?
Vitamin K is a crucial factor in blood clotting, among other functions. A deficiency can cause widespread internal hemorrhaging. This is the mechanism used by anticoagulant rat poisons such as warfarin: they interfere with vitamin K activation, so the rodent bleeds to death.
Vitamin K has two primary natural forms: K1 (phylloquinone), which is naturally found in leafy green and cruciferous vegetables; and K2 (menaquinone), which is produced by the bacteria in the gut. MSBC – vitamin K3 – must be converted by the liver into menaquinone before the body can use it.
MSBC is banned in human multivitamin products due to potential toxicity. Adverse effects from large doses include anemia and brain damage. But it is frequently added to pet food.
Do Dogs Need Vitamin K?
Dogs don’t need vitamin K in their food. Because the gut bacteria produce all the vitamin K a dog needs, it is not a required nutrient. Nevertheless, it’s found in many dog foods. This may be because a company producing both dog and cat food uses one standard vitamin-mineral premix. It would cost more to use different premixes for the two species.
Why do premixes use menadione instead of K1 or K2?
For one thing, it’s much cheaper. Additionally, sodium bisulfate, the compound attached to menadione to create MSBC, is a palatant (taste enhancer), urinary acidifier, and antimicrobial.
Menadione Safety Studies
AAFCO, the organization that sets nutritional standards for pet food, recently conducted a review of MSBC to assess its safety. The committee concluded that it was fine to use in food for all animals. They based their conclusion on “confidential industry data,” 2014 European Food Safety Authority opinion, and an “independent review” of the scientific literature. However, the committee report cited data from 1940s to support their conclusion, while ignoring dozens of more recent studies reporting adverse effects.
Several studies cited in the References below show some of the potential toxicities of menadione, and in many cases highlight the fact that menadione induces oxidative stress. It’s interesting to note that in some of these experiments, menadione was used as to deliberately trigger oxidative stress.
How Menadione Can Harm Your Dog
Menadione can interfere with the function of glutathione, the body’s most powerful antioxidant, leading to oxidative damage to cell membranes.
Glutathione is a crucial healing and cleansing agent. Without it, cells would die. The immune system wouldn’t work and toxic overload could cause the liver to fail. Glutathione supports the liver, repairs tissues, protects the body’s energy sources and helps control chronic inflammation. It stimulates natural killer (NK) and T cells to strengthen the immune system.
As an antioxidant, glutathione helps control free radicals. Factors like poor diet, drugs and other toxins create free radicals that lead to oxidative stress and disease. Free radical damage is linked to diseases like cancer, joint disease, heart, liver and kidney disease, as well as premature aging.
When left unchecked, free radicals cause damage to the cells, proteins and DNA in your dog’s body. Glutathione helps slow the aging process and boost the immune system by neutralizing free radicals to reduce oxidative stress in your dog.
Glutathione also eliminates poisons such as drugs and pollutants. Veterinarians may give it to dogs in emergencies involving poisoning and toxicity.
An Unknown Quantity In Dog Food
Because AAFCO relied on “confidential” industry studies, we cannot know the levels of MSBC that are in pet food. Because of sodium bisulfate’s properties, there may be far more than could conceivably be helpful.
And we do not know the actual duration of any “long-term” studies performed … though we may get a hint from the study standards for feeding tests that are, at most, six months long. Given that dogs may be eating a particular food for many years, if not their entire lives, is this a fair conclusion? Perhaps not, but it is exactly the conclusion desired by the pet food industry … and now helpfully provided by AAFCO.
MSBC is an artificial substance not needed by the body, with potential adverse effects. We recommend avoiding foods that contain it.
Bladen CL et al. Effects of low-dose ionizing radiation and menadione, an inducer of oxidative stress, alone and in combination in a vertebrate embryo model. Radiat Res. 2012;178(5):499-503.
Loor G, et al. Menadione triggers cell death through ROS-dependent mechanisms involving PARP activation without requiring apoptosis. Free Radic Biol Med. 2010;49(12):1925-1936.
Kim IS, Jin I, Yoon HS. Decarbonylated cyclophilin A Cpr1 protein protects Saccharomyces cerevisiae KNU5377Y when exposed to stress induced by menadione. Cell Stress Chaperones. 2011;16(1):1-14.
Falone S, Sannino A, Romeo S, et al. Protective effect of 1950 MHz electromagnetic field in human neuroblastoma cells challenged with menadione. Sci Rep. 2018;8(1):13234. Published 2018 Sep 5.
Yeo HS, Shehzad A, Lee YS. Prostaglandin E2 blocks menadione-induced apoptosis through the Ras/Raf/Erk signaling pathway in promonocytic leukemia cell lines. Mol Cells. 2012;33(4):371-378.
Katikireddy KR, White TL, Miyajima T, et al. NQO1 downregulation potentiates menadione-induced endothelial-mesenchymal transition during rosette formation in Fuchs endothelial corneal dystrophy. Free Radic Biol Med. 2018;116:19-30.
Thomas NO, Shay KP, Hagen TM. Age-related loss of mitochondrial glutathione exacerbates menadione-induced inhibition of Complex I. Redox Biol. 2019;22:101155.
Halilovic A, Schmedt T, Benischke AS, et al. Menadione-Induced DNA Damage Leads to Mitochondrial Dysfunction and Fragmentation During Rosette Formation in Fuchs Endothelial Corneal Dystrophy. Antioxid Redox Signal. 2016;24(18):1072-1083.