Vitamin E in a raw diet
In the article about supplements, I mentioned that I add vitamin E to the diet of my cats. I’ve also mentioned vitamin E in my article about lipids. In today’s article, I’m going to go into more detail about vitamin E: why and how much you should give to your cat.
Note: Before reading this article, I recommend you to read the articles about lipids as some notions from this article will be necessary to understand the nutritional requirement of vitamin E.
What’s vitamin E?
Vitamins are organic elements present in very small amounts in the body that are required for normal body function and metabolism. Vitamins can’t be sufficiently synthesized (or not at all) by the body and need to be provided in the diet. Vitamin E is part of the fat-soluble vitamins group, along with vitamins A, D, and K.
The term vitamin E actually designates a family of compounds called tocopherols and tocotrienols. The most potent form of vitamin E is alpha-tocopherol.
The main function of vitamin E is to be an antioxidant. As we have seen in the article about lipids, polyunsaturated fatty acids (PUFA) are fragile and are easily oxidized. These PUFA are present in foods and as well as in the membrane of the cells of the body. Once the fats are oxidized, they become rancid and lose their nutritional value. When the cell's membrane is oxidized, it impairs its normal functioning. One of the roles of vitamin E is to protect the PUFA from oxidation both in the food eaten and in the body cells. Vitamin E also protects vitamin A and some amino acids from oxidation.
Deficiency in vitamin E
Vitamin E deficiency isn't common. However, it may happen in a diet rich in PUFA (like, for example, a diet with a high composition of fish). In that case, it can cause pansteatitis or yellow fat disease in cats. This disease is characterized by a yellow-brown coloration of the fat and inflammation, anorexia, depression, fever, reluctance to move…
Many cases of pansteatitis happened in cats fed exclusively with canned tuna pet food, when not enough vitamin E was added to the industrial pet food.
In two other cases, pansteatitis was caused by a homemade diet made almost exclusively of pig’s brain, which—as we have seen in the article about lipids—is rich in DHA, a polyunsaturated fatty acid.
Excess vitamin E
Fat-soluble vitamins can be toxic if fed in too high quantities. Vitamin E is the least toxic of the group. It has been reported that excess vitamin E could cause prolonged blood clotting as well as cause interactions with the effects of vitamin D and K.
However, there are not enough studies at the moment to define what would be a safe upper limit.
Vitamin E requirements
Because the main role of vitamin E is to protect the polyunsaturated fatty acids from oxidation, the requirement of vitamin E is directly linked to the amount of PUFA in the diet.
The recommended requirements of vitamin E defined for adult cats in the NRC are:
10 mg/1000 kcal of diet equivalent to 38 mg per kg of DM with 4000 kcal/kg
30 mg/1000 kcal of diet equivalent to 120 mg per kg of DM with 4000 kcal/kg for diets high in PUFA
Raw diets, especially if they contain fish or fish oil, are high in PUFA. For this reason, I recommend following the second guideline. For a 4 kg cat eating 200 kcal, this guideline is roughly equivalent to 6 mg of vitamin E a day.
The FEDIAF recommends adding 3.35 mg to 6.7 mg of vitamin E per g of PUFA. This recommendation is much higher than the one of the NRC, probably to account for the oxidation during the production and storage of industrial pet food.
Selenium is another nutrient that plays an antioxidant role, similar to vitamin E. Therefore, selenium could spare vitamin E. However, there is no clearly-defined relationship between selenium and vitamin E.
Where is vitamin E found?
Vitamin E is found mainly in plants, seeds, and plant oil. The oils which are the richest in vitamin E are wheat germ oil (149 mg/100 g), sunflower oil (41 mg/100 g), and canola oil (17 mg/100 g). For the seeds and nuts, sunflower seeds (35 mg/100 g) and almonds (24 mg/100 g) are the richest.
Animal products are lower in vitamin E: chicken fat contains 2.7 mg/100 g and egg yolk contains 2.3 mg/100 g.
Because animal products are low in vitamin E, raw diets will also be low in vitamin E and won’t satisfy your cat’s requirement.
That’s why it’s recommended to supplement the diet with vitamin E, especially if you add fish, fish oil, or brain.
How to supplement a diet with vitamin E?
A pitfall to avoid is to use plant oil to supplement it. In fact, while oils contain high quantities of vitamin E, they are also high in PUFA. Using these oils will increase the vitamin E requirement: it’s a vicious circle.
For example :
Wheat germ oil contains 149 mg of vitamin E per 100 g, but it also contains 61 g of PUFA per 100 g.
So, adding 5 g of wheat germ oil will bring 7.45 mg of vitamin E but at the same time, it increases the requirement by 1.83 mg to 20 mg of vitamin E, depending on if you follow the NRC or FEDIAF recommendation.
Similarly, using seeds isn’t appropriate for cats as they are high in calories and contain a lot of compounds that prevent the good absorption of nutrients.
Another common pitfall is counting on the vitamin E added in fish oil. This vitamin E is used to protect the PUFA in the fish oil from oxidation, so won’t be used for your cat’s daily requirements.
For all these reasons, the easiest way to supplement a raw diet is to use a natural vitamin E supplement. I personally like using a liquid vitamin E with a dropper from Solgar or NOW, and giving it daily.
If you prepare the raw diet of your cat in a minced batch you may want to use vitamin E in powder and add around 100 mg to 200 mg per kg of food in addition to your cat’s requirement. It will be used as a food antioxidant to preserve the batch. This amount of vitamin E won’t go toward your cat’s requirement but will be “sacrificed” to protect the batch from lipid oxidation.
Avoid buying vitamin E containing dl-alpha-tocopherol: this is the synthetic version of vitamin E and it’s less potent than the natural d-alpha-tocopherol. The natural d-alpha-tocopherol is generally extracted and purified from seed oils. The ideal would be a vitamin E containing d-alpha-tocopherol as well as mixed-tocopherols, to have both the antioxidant action in the body and the food respectively.
As vitamin E is relatively non-toxic, the risk of excess is very low and the supplementation is not dangerous.
In case you encounter it, d-alpha-tocopherol can also be designated as RRR-alpha-tocopherol, while the synthetic form dl-alpha-tocopherol can be designated as all-rac-alpha-tocopherol.
Some vitamin E supplements will be in the form of d-alpha-tocopheryl acetate or d-alpha-tocopheryl succinate, which is the d-alpha-tocopherol combined with another molecule to make it more stable or in a dry/powder form.
How do cats get vitamin E in nature?
When I suggest adding supplements to a raw diet, a recurrent and rightful question is: “but how do cats get vitamin E in nature?”. Sadly, we don’t have much data on the vitamin E content of wild prey that cats would hunt.
However, from the data that we have on domestic whole prey like rats, chickens, and quails, it seems that they are significantly higher in vitamin E than meat. This is likely due to the fact that whole prey is less processed than meat: they are not cut and dressed. Every process can cause the oxidation of lipids and so a loss of vitamin E.
Another factor is that the content of vitamin E in meat is highly dependent on the amount of vitamin E in the feed of the animals. It’s very possible that wild preys have a diet high in vitamin E as their diet is not processed. Therefore, it would not be surprising that wild prey contains enough vitamin E to cover the requirements of cats.
Finally, it’s also possible that the level of antioxidants needed for a wild cat to survive is lower than the ideal level of antioxidants for our domestic cats to have a long, healthy life.
To conclude, vitamin E is important and often lacking in a homemade diet, especially if you feed fish or fish oil as your cat could be at risk of pansteatitis. I recommend using a natural vitamin E supplement, as it’s hard to provide this vitamin with whole food.
Vitamin E in raw meat & whole prey
| mg of vitamin E / 100g | mg of vitamin E / 1000kcal | |
|---|---|---|
| Cut | ||
| Chicken breast | 0.56 | 4.67 |
| Chicken breast with skin | 0.27 | 1.57 |
| Beef chuck stew meat | 0.17 | 1.33 |
| Ground beef 10% | 0.17 | 0.97 |
| Lamb shoulder chop | 0.21 | 0.81 |
| Pork tenderloin | 0.22 | 1.83 |
| Pork leg shank | 0.31 | 1.61 |
| Turkey breast | 0.09 | 0.79 |
| Turkey thigh with skin | 0.16 | 0.99 |
| Veal escalope | 0.15 | 1.39 |
| Veal shoulder | 0.26 | 2.10 |
| Venison | 0.2 | 1.67 |
| Whole Prey | ||
| Mouse, neonatal<3g | 0.67 | 7.25 |
| Mouse, juvenil 3-10g | 2.12 | 17.52 |
| Mouse, adult > 10g | 2.20 | 12.81 |
| Guinea pig, 10 week | 0.51 | 2.32 |
| Rat, neonatal < 10g | 6.56 | 59.47 |
| Rat, adult > 50g | 3.16 | 14.64 |
| Quail, japanese | 1.55 | 6.59 |
Supplement calculator
Vitamin E convertor
Sources
Linda P. Case et al. 2015. Canine and Feline Nutrition.
National Research Council. 2006. Nutrient Requirements of Dogs and Cats. Washington, DC: The National Academies Press.
Wouter H. Hendriks, Yuben B. Wu, Rick G. Shields, Mark Newcomb, Kay J. Rutherfurd, Tsegaw Belay, Jonathan Wilson, Vitamin E Requirement of Adult Cats Increases Slightly with High Dietary Intake of Polyunsaturated Fatty Acids, The Journal of Nutrition, Volume 132, Issue 6, June 2002, Pages 1613S–1615S.
Vitamin E—Food Chemistry, Composition, and Analysis, edited by Ronald Eitenmiller and Junsoo Lee, 2004
Dierenfeld, Ellen & Alcorn, Heather & Jacobsen, Krista. (2002). Nutrient Composition of Whole Vertebrate Prey (Excluding Fish) Fed in Zoos. 7994.