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05-08-2015, 05:43 AM | #1 |
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| Vitamin K and menadione in dog food. Is it necessary? Hi, In another thread on dog food and canine nutrition, the question came up about whether menadione (vitamin K3) is necessary in dog food, and if it is, whether it is a safe ingredient. There are many, many articles about it in the popular press, but they tend to go around in circles, and don't cite any scientific articles to back it up. For that reason, I'm not going to post any articles from the popular press on this subject, not even from the Skeptvet. I'm going to try to find the facts about menadione. First, here is the section on vitamin K from a chapter from the book "Canine and Feline Nutrition. A Resource for Companion Animal Professionals, Third Edition" by Case, LP, Daristotle, L, Hayek, M, and Raasch, MF. 2011. Mosby Elsevier Press, Maryland Heights, Missouri. Vitamin K Vitamin K comprises a group of compounds called the quinones. Vitamin K1 (phylloquinone) occurs naturally in green plants, and vitamin K2 (menaquinone) is synthesized by bacteria in the large intestine. Several synthetic analogues have also been prepared. Menadione (vitamin K3), the most common form of synthetic vitamin K, has a vitamin activity two to three times higher than that of natural K1. Like all animals, dogs and cats have a metabolic need for vitamin K. However, at least a portion of this requirement can be obtained from bacterial synthesis of the vitamin in the intestine. The best-known function of vitamin K is its role in the blood clotting mechanism. Specifically, it is required for the liver's synthesis of prothrombin (factor II) and three other clotting factors--factors VII, IX, and X--in the liver. Vitamin K acts as a cofactor for the enzyme that carboxylates glutamic acid residues in a prothrombin-precursor protein to form gamma-carboxyglutamic acid. The conversion of these amino acids facilitates the binding of prothrombin to calcium and phospholipids., a process necessary for the occurrence of normal blood clotting. It appears that vitamin K has a similar role in the activation of other proteins that contain glutamic acid residues in bone and kidney tissue. Vitamin K is found in green, leafy plants such as spinach, kale, cabbage, and cauliflower. In general, animal sources contain lower amounts of vitamin K; liver, egg, and certain fish meals are fairly good sources. The synthesis of vitamin K by bacteria in the large intestine of dogs and cats can contribute at least a portion, if not all, of the daily requirement in these species. Therefore a dietary supply of this vitamin only becomes significant when bacterial populations in the large intestine are reduced, such as during medical treatment with certain types of antibiotics, or when there is interference with the absorption or use of vitamin K from bacterial sources. Vitamin K is also routinely administered in the treatment of rodenticide poisoning in pets because the active ingredient in many of these poisons is an anticoagulant. |
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05-08-2015, 05:48 AM | #2 | |
YT 3000 Club Member Join Date: Apr 2013 Location: Urbana, IL USA
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05-08-2015, 06:54 AM | #3 | |
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I know some people here hate the "Dog food adviser", but he has written a good article on the subject, that is much easier than reading these studies. He also has references in this article. The Controversy Over Menadione in Dog Food Vit K 1 and Vit K 2 are natural but Vit K 3 (menadione) is synthetic and all forms of the chemical must first undergo the cellular process of alkylation before they can be used by the body. It is not used directly as a nutritional supplement due to high toxicity and low stability MENADIONE (Vitamin K3) I think it's important to note that menadione has been banned from human supplements Vitamin K | Linus Pauling Institute | Oregon State University "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 K11. 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 infants12; therefore, menadione is no longer used for treatment of vitamin K deficiency13. 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.14". Taken from the The Controversy Over Menadione in Dog Food The bottom line for me is if it's not safe for humans, I don't think I want it in my dog food. They can still use it in animal "feed", but my dog isn't a farm animal that will be sent to market after a certain age. Farmers don't care if they animals get cancer at 10 years old, but our motivation is to keep our dogs alive and healthy as long as possible. Many of the large food companies have voluntarily taken it out, just because some people made enough noise and consumers started buying foods without it, although you can still find it in some foods.
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05-08-2015, 07:12 AM | #4 | |
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05-08-2015, 07:16 AM | #5 | |
I ♥ Joey & Ralphie! Donating Member | Quote:
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05-08-2015, 07:23 AM | #6 |
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| A (nearly) complete waste of time. I had to go to the library to find a copy of the AAFCO Dog Food Nutrient Profiles since the AAFCO wants to charge people $108 for a copy of the book . The 2014 AAFCO Official Publication had this to say on vitamin K supplements for dogs: "No minimum levels for biotin or vitamin K (or equivalent) were established, although the subcommittee would not object to their inclusion as ingredients in dog foods at trace levels." I sure am glad that I didn't waste my money on that book!!! The AAFCO did not define what they meant by "trace levels." I guess we have to read our dog food labels and question the companies directly. While I was at the library, I read the section on AAFCO feeding trials mentioned in another Yorkietalk thread. Very interesting stuff there--eight dogs are fed exclusively on the dog food being tested. Two dogs are allowed to drop out of the test for reasons not related to the testing. To pass the feeding test, the dogs must show no signs of nutrient deficiency or excess. Blood tests are taken before and after the feeding trial to assess health and liver function. Vet exams for general health are also performed. The dogs cannot lose more than 15% of their starting weight while they are in the feeding trial. There were more details, but since I was researching vitamin K, I didn't write them down... |
05-08-2015, 07:28 AM | #7 |
YT 3000 Club Member Join Date: Apr 2013 Location: Urbana, IL USA
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| Hmmm. I think that we will have to start writing directly to companies to ask them why they use a vitamin K supplement that is not required. My Wellness Core Grain Free Small Breed dog food does not contain menadione. |
05-08-2015, 07:28 AM | #8 | |
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05-08-2015, 07:34 AM | #9 | |
Furbutts = LOVE Donating Member Moderator | Quote:
Thanks for posting this.
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05-08-2015, 07:39 AM | #10 |
I ♥ Joey & Ralphie! Donating Member | Yeah, it use to be in Royal Canin, they took it out of some of their foods, but not all. Now. I'm convinced I'm remembering it wrong, I can't find out any reference to it being used as a preservative. The good news is that the natural form of vit K is found in broccoli and my nickname for my two boys is the broccoli brothers. They go nuts when I cook broccoli and insist on having some whenever I eat it.
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05-08-2015, 07:47 AM | #11 |
YT 3000 Club Member Join Date: Apr 2013 Location: Urbana, IL USA
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| I checked out the DFA's references on menadione toxicity, and most of them involved large amounts of menadione (about 1 mM solution, which is quite a lot from a biological standpoint) that would never be purposefully fed to a dog. I think they were concerned about human exposure in labs that work with large quantities of menadione as a chemical reagent? One of the more interesting studies involved the injection of a human subject with menadione to counteract rat poisoning. He developed eczema at the injection site. Again, not likely to happen with dog food. I found the following from the Handbook of Preservatives, by Michael and Irene Ash (2004): |
05-08-2015, 07:50 AM | #12 | |
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05-08-2015, 07:53 AM | #13 | |
T. Bumpkins & Co. Donating YT Member Join Date: Dec 2008 Location: New England
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I recall it being used as a preservative in dog food as well, but I can't remember more about it. My dog's have broccoli added to their food as well although I give it as raw pieces and they love it. Another great and better source of vitamin K is Kale, followed by spinach. I avoid spinach in this breed because it is high in oxalate and there are many dogs who can be prone to being stone makers in our breed. Kale is a low oxalate food, often mistaken for being high in oxalate simply because it is a leafy green. So I do add kale to my dogs food when I have it.
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05-08-2015, 07:54 AM | #14 |
YT 3000 Club Member Join Date: Apr 2013 Location: Urbana, IL USA
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| Despite there being a TV program called "8 is enough" , no, I don't think that 8 dogs is enough for a feeding trial. I wish there could be more, but I expect it's because these kinds of trials are expensive . At least we can choose from dog foods that have been around for many years and have a good track record. That's probably the best we can do (besides home cooking, of course). |
05-08-2015, 07:57 AM | #15 | |
I ♥ Joey & Ralphie! Donating Member | Quote:
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