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Today we are moving on to a nutrient that can be confusing to a low of feeders: Vitamin E.
WHAT IS IT
Vitamin E (scientific name is tocopherol) refers to 8 different vitamers (that we will discuss below). Vitamin E is a fat soluble vitamin.
ADDITIONAL BACKGROUND INFORMATION
Polyunsaturated fat is a type of fat found in the body and the diet. In the diet it comes from vegetable oils, fish, fish oils, nuts, and seeds. It can also be found in land animals to a lesser degree. Poultry fat and skin can contribute appreciable amounts of these fatty acids to the diet.
It is prone to oxidation.
WHAT DOES IT DO
Dogs, like humans, are made up of cells. These cells have a fatty membrane that allow for things to go in and out of the cell in a controlled manner. The membranes are made up of fatty acids (a topic we will go into great detail later). Just like when we think of fish oil increasing the need for vitamin E and vitamin E acting as a preservative in many oils, vitamin E acts as an antioxidant in the same exact way in the body.
The cellular membrane is made up of polyunsaturated fat. These fats are fragile and when they oxidize they shatter like glass- affecting all other things around it. It has a domino-like effect. When one fatty acid is oxidized, it becomes a free radical and destroys the other fatty acids.
It is imperative, then, that this chain reaction be stopped so that these broken fatty acids do not move on to destroy the membrane, organelles, and even the DNA.
Enter vitamin E! Vitamin E’s chief function is to protect fatty acids in the cell (and therefore everything else in the cell).
Once vitamin E is used to stop the chain reaction of oxidation, it must be rejuvenated. The entire antioxidant defence system actually goes beyond just vitamin E. Vitamin C, selenium, and manganese are all key players. Dogs are able to synthesize vitamin C (but food sources can still be beneficial). Selenium and manganese will be covered in the future.
It is important to note that vitamin E prevents the chain reaction from happening. Therefore, it is still important to be mindful of the amount of polyunsaturated fat in the dog’s diet. As mentioned before, vitamin E will need to be repaired by other team members. So while we tend to say some types of fat increase vitamin E needs, matching the vitamin E levels is only part of the picture and it is best to not overdo it on these fragile lipids. More on this in a future lesson.
Vitamin E is actually the name for 8 different vitamers. There are 4 tocopherols and 4 tocotrienols. The one we meet the daily requirement with is called d-alpha tocopherol.
Tocopherol comes from the Greek and originally meant “to carry, to bear, birth.” Vitamin E deficiency in dogs affects the reproductive system.
Anywhere that is rich in these polyunsaturated fatty acids will be affected the most. Therefore, neurological disturbances can also be seen. The brain is extremely rich in polyunsaturated fat (as DHA) and to do its job results in the byproducts of oxidants. It is critical that optimal vitamin E be provided in the diet to protect the body from oxidative harm.
In humans, low vitamin E has also been linked to cancer, heart disease, joint degeneration, poor wound healing, skin disturbances and gut disturbances.
In dogs, we can also see gut and skin disturbances, poor wound healing, anorexia, eye disease, and in severe cases- death.
Given that vitamin E protects by extension all things in the cell, it would not be off base to speculate that chronic illness may possibly be related to low antioxidant diets commonly fed to dogs.
A diet that is low in vitamin E and high in polyunsaturated fat is the biggest risk factor for vitamin E deficiencies. Because vitamin E is a fat soluble, inadequate dietary fat or disturbances to digestion can also harm vitamin E status.
A traditional raw diet that only has meat, bones, and organs can still have varying ranges of polyunsaturated fat. Most raw diets are low in vitamin E relative to the amount the dog needs- even with a low polyunsaturated fatty acid intake.
Canine athletes will require more vitamin E. Things that require high energy- building things, tearing them down, building more things- produce oxidants.
Some conditions, such as chronic kidney disease, will also benefit from extra vitamin E and caution to not use plant oils high in polyunsaturated fat (fish and fish oils are still beneficial)
Unliked vitamin A and vitamin D, vitamin E doesn’t really have a toxic excess. Remember that vitamin E refers to d-alpha tocopherol primarily, but also the other tocopherols and tocotrienols. High amounts of d-alpha tocopherol, especially when fed without the other tocopherols, can begin to have the opposite effect. Mega dosing can cause vitamin E to have a more oxidative effect. Therefore, it is important to not supplement carelessly even though the safe upper limit is not specifically defined.
High doses of vitamin E may hurt vitamin K status.
Vitamin E can be found in plants because plants use a process called photosynthesis. This process uses oxygen, water, and the sun to make glucose. This process requires that the plants have adequate antioxidants and so it is not surprising that we see vitamin E scattered among plant based foods.
Grass fed and finished beef will also have higher vitamin E than factory farmed because of the diet.
If we were to look at foods just based on their vitamin E content, it would appear that wheat germ oil would be the best source. However, wheat germ oil is also extremely rich in polyunsaturated fat. Therefore, the vitamin E in the oil should not be counted toward daily requirements for the body’s metabolic functions. Similarly, brain should also not be used for vitamin E requirements because it is so rich in polyunsaturated fat.
Supplements tend to come in a few forms:
- As d-alpha tocopherol (with nothing else)
- As dl-alpha tocopherol
- As d-alpha tocopherol with mixed tocopherols
- As d-alpha tocopherol with mixed tocopherols and tocotrienols
Dl-alpha tocopherol is synthetic and is less bioactive as d-alpha tocopherol. I do not recommend you use dl-alpha tocopherol.
I recommend using d-alpha tocopherol with mixed tocopherols (and tocotrienols when possible). The tocopherols outside of d-alpha may have unique benefits and so I opt to include them when possible.
However, it can be somewhat difficult getting smaller dogs a small enough dose of d-alpha with mixed tocopherols. A lot of the liquid ones that are small enough does (like NOW) are d-alpha only. If you find yourself in this category, try to be sure to include a wide array of plant foods in the diet.
The tocotrienols can also be found in some supplements, but data is lacking on how absorbable they are. When possible, I prefer to use a supplement with d-alpha tocopherol with mixed tocopherols and tocotrienols.
TOPPING COMMERCIAL FOOD
Kibble: Provide fresh plant foods. A low dose vitamin E supplement can also be added. Supplement f adding fish or fish oil.
Raw: Most raw foods that are properly formulated should have enough vitamin E. If you do not see it on the ingredient label, feel free to reach out and share the food that you have.
Canned: Provide fresh plant foods
HOW MUCH DOES A DOG NEED?
You are welcome to simply use the calculator that I built here to determine vitamin E requirements. This will not account for extra polyunsaturated fat in the diet.
If you are feeding oily fish, fish oil, plant oils (like sunflower, hemp etc), consider supplementing.
The more polyunsaturated fat you need, the more vitamin E is required!
Brands that I use include NOW, Solgar, Jarrow, and Standard Process (vet only).
MORE ON VITAMIN E
I have written on vitamin E here at Dogly. Here is one that expands on vitamin E in the diet:
- Identify vitamin E in the current diet
- Where is the vitamin E in the diet? How often is vitamin E fed?
- Is this a good source?
- Is it from food? Is the food high in polyunsaturated fat? Is it a supplement? If so, what form? Any tocopherols or tocotrienols?
- How much is in the diet?
- Applicable for homemade diets and some commercial whole food diets that provide ingredient amounts,
- Does your dog have an increased need for vitamin E?
When providing ingredient amounts, please include your dog’s age, weight, and ideal weight.
In this section I bring you recommended watching. I love this course by Chris Masterjohn, Phd. Do note that this is for human nutrition and not all applies to dogs. However, his descriptions of what is happening in the body is correct.
Reading can also include:
The vitamins Chapter in Canine and Feline Nutrition and/or Small Animal Clinical Nutrition
NRC Nutrient Requirements of Dogs and Cats (2006)
Canine and Feline Nutrition
Small Animal Clinical Nutrition
Chris Masterjohn, PhD Vitamins and Minerals