Vitamin E

Feed vitamin E is commonly made by chemical synthesis. Producers turn the resulting alpha-tocopherol into a more stable acetate, then sell it as an oil or carrier powder that food makers can measure into a premix.^6,7,8

1. 01 // Source Chemical building blocks Modern synthetic production uses trimethylhydroquinone and isophytol, each made through several earlier steps.
2. 02 // Process Make alpha-tocopherol The two building blocks are joined to form synthetic alpha-tocopherol.
3. 03 // Process Make stable acetate Converting alpha-tocopherol to its acetate form improves its stability during storage.
4. 04 // Output Oil or powder Feed makers receive the acetate as an oil or as powder carried on materials such as starch and silica.

1. 01

   Protects cell membranes from oxidation

   Vitamin E is a chain-breaking antioxidant in cell membranes. In a 40-dog feeding trial, serum vitamin E rose with intake, and a blood marker of fat oxidation fell at 445 IU per kg of food.¹⁵

   1. Strong
   2. Some
   3. Thin
   4. None
2. 02

   Better endurance in racing sled dogs

   Among 670 Iditarod dogs, those with higher prerace blood vitamin E were 1.9 times more likely to finish. That is an association. No trial has shown that feeding more makes dogs finish.^16,17

   1. Strong
   2. Some
   3. Thin
   4. None

1. 01

   Completes the nutrient profile

   A vitamin premix lets the manufacturer meet the finished food's vitamin E target while accounting for what the other ingredients contribute and what storage may cost.¹

2. 02

   Balances fatty recipes

   Polyunsaturated fats raise a diet's vitamin E target under AAFCO guidance. Formulators have to balance the finished recipe, which an ingredient line cannot reveal.¹

3. 03

   Mixes at feed scale

   Synthetic acetate is sold as oil and as carrier powder. An industry-authored review describes adsorbate powders as a lower-cost way to handle vitamin E in feed production.^7,8

How much AAFCO lists 50 IU per kg of dry dog food as the minimum for growth and adult maintenance; that is a finished-food target.¹

1. Vets say

   Dogs need vitamin E in a complete diet

   Evidence

   1. Strong
   2. Some
   3. Thin
   4. None

   AAFCO sets a minimum of 50 IU per kg of dry food for both growth and adult maintenance. Vitamin E is essential, but the ingredient list does not reveal the finished food's vitamin E level.^1,10

2. Brands say

   Extra vitamin E boosts a dog's immunity

   Outruns the evidence

   Evidence

   1. Strong
   2. Some
   3. Thin
   4. None

   A 17-week trial in 32 older beagles found changes in T-cell measures at different dietary levels. A separate 15-dog fish oil trial measured a laboratory immune response. Neither tested whether dogs had fewer infections.^2,3

3. Owners say

   Extra vitamin E relieves arthritis pain

   Outruns the evidence

   Evidence

   1. Strong
   2. Some
   3. Thin
   4. None

   A 15-dog trial after surgically induced joint injury found some favorable pain and inflammation measures. A 57-dog trial of naturally occurring osteoarthritis found no improvement in pain, lameness or rescue pain relief. A routine arthritis recommendation goes too far.^4,5

4. Brands say

   Vitamin E supplement keeps kibble fats fresh

   Outruns the evidence

   Evidence

   1. Strong
   2. Some
   3. Thin
   4. None

   AAFCO identifies alpha-tocopherol acetate as a vitamin source and mixed tocopherols as preservatives. The acetate is made for stability during storage; its supplement line does not tell you which ingredient protects the food's fats.^7,9

1. 1998 // Case report, eye and tissue exams

   Table-scrap diet left hunting dogs losing their vision¹⁴

   Walker Hounds and Beagles fed table scraps

   Found. Every dog had retinal degeneration, and severity varied with age. Their plasma, serum and tissue vitamin E measured 10 to 40% of control values, consistent with dietary vitamin E deficiency.

   What it means. Scrap or improvised diets without a vitamin source risk real deficiency. A complete and balanced food is formulated to prevent it.

2. 2000 // Feeding trial, 4 groups

   More dietary vitamin E lowered a fat oxidation marker¹⁵

   40 healthy adult dogs, plus 40 cats; authors from Hill's

   Found. Over 6 weeks, serum vitamin E rose as diet levels increased. A blood marker of fat oxidation dropped significantly only from 445 IU vitamin E per kg of food, as fed.

   What it means. Higher vitamin E levels shift lab markers of oxidation, but this brand-authored trial measured no health outcome in the dogs.

3. 2000 // Feeding trial, 3 groups

   Antioxidant supplement cut a DNA damage marker in sled dogs¹⁶

   62 Alaskan sled dogs

   Found. Dogs given 400 units of vitamin E acetate, beta-carotene and lutein daily for 1 month had higher blood antioxidants, and a DNA damage marker fell during 3 days of exercise.

   What it means. Working dogs showed less oxidative damage with extra antioxidants, but the mix hides vitamin E's share and performance was not measured.

4. 2001 // Blood samples before a race

   Iditarod dogs with higher vitamin E finished more often¹⁷

   670 sled dogs in the 1998 Iditarod

   Found. Dogs with prerace plasma vitamin E above 40.7 micrograms per mL were 1.9 times more likely to finish. Team vitamin E status did not predict team speed.

   What it means. Good vitamin E status goes with endurance, but this was an observation, so it does not show that a capsule would help.

5. 2012 // Single oral dose test

   Some cocker spaniels need prescribed vitamin E doses¹⁸

   8 English Cocker Spaniels with familial deficiency, 5 normal dogs

   Found. After one large oral dose, affected dogs peaked at about 17.9 micrograms per mL of plasma vitamin E versus about 47.6 in normal dogs. Seven of 8 still reached the normal range.

   What it means. A few dogs run low on vitamin E despite a normal diet. They need a vet-directed dose, not just the food's level.