Vitamin E and Our Pets
Vitamin E and concern that our pets may be deficient often come up, so let’s have a look at this:
First, what is Vitamin E’s function in the body of a carnivore?
Vitamin E is a fat-soluble antioxidant that's important to prevent lipid oxidation and free radical damage. However it is not as much of an issue with raw saturated fats as with plant oils, PUFAs and cooked saturated fats. Heat and light are the main culprits and PUFAs (like plant oils) oxidize more rapidly than the monounsaturated fatty acids.
Since Vitamin E is fat soluble and is stored in the liver and body tissues, small amounts of vitamin E will stay in the body for a long time. There can be a risk of overdosing with supplements but not with natural Vitamin E as food source.
Synthetic vitamins can never replace real food. Supplements in general, are not as bio available as what nature offers in the correct balance. Since PMR fed dogs do not need to metabolize carbs, their need for some nutrients like Vit C and E for example is less than for kibble fed dogs.
Antioxidants in whole foods (in addition to being much more effective), do not interfere with the body's ability to use free radicals constructively or it's ability to use oxygen (they enhance both). Despite modern advances, the best source of nutrients, by far, is natural food! When provided a whole animal diet, dogs and cats have the ability to produce their own antioxidants. Whole animal carcasses support this production with nutrients like vitamins A, C, E, and minerals like copper, zinc, and selenium.
Vitamin E deficiencies are quite rare in dogs, but when they do develop, the typical symptoms can include poor vision, neurological abnormalities, reproductive dysfunction and an impaired immune system. Also there can be underlying medical issues that prevent the absorption of Vitamin E.
It’s said that dogs need no more than 20 IU of Vitamin E daily. (1IU=0.67mg). However, there really isn't enough research available yet with purely raw fed dogs to say for sure how much they would need and the bio-availability of supplements to be able to advise on amounts. Requirement is dependent on dietary levels of PUFA, antioxidants, sulfur amino acids, and selenium. Requirements of both vitamin E and selenium are greatly dependent on the dietary concentrations of each and they are mutually replaceable above certain limits.
Establishing vitamin E requirements is further complicated because the body stores both vitamin E and selenium. A number of studies to establish requirements for both nutrients have underestimated the requirements by failing to account for their augmentation from body stores as well as experimental dietary concentrations. (DSM in Animal Nutrition & Health) For all classes of dogs, 50 IU of vitamin E is recommended per kg (22.7 IU per lb) of diet. The need for supplementation of vitamin E depends on the requirement of individuals, how food is processed and the amount of available vitamin E in food sources. If diets have relatively large quantities of meat, fat, organs, and eggs, plenty of vitamin E will be provided.
As for selenium, fish, seafood, pork, beef, turkey, chicken, organ meats and eggs are good sources.
The stability of the fat source is important as large amounts of PUFA can cause vitamin E deficiency. Also stress, exercise, infection and tissue trauma all increase vitamin E requirements (Nockels, 1991).
If a lot of fish or fish oil is in the feeding plan, extra Vitamin E will be needed, but preferably not soy derived....
Excessive vitamin E can affect blood clotting by inhibiting normal platelet aggregation (clumping) This effect has been noted with vitamin E supplements, but not when consuming diets containing vitamin E. Naturally sourced vitamin E is called RRR-alpha-tocopherol (commonly labeled as d-alpha-tocopherol); the synthetically produced form is all rac-alpha-tocopherol (commonly labeled as dl-alpha-tocopherol).
Conversion rules are as follows:
• To convert from mg to IU: 1 mg of alpha-tocopherol is equivalent to 1.49 IU of the natural form or 2.22 IU of the synthetic form.