Vitamin E is an important part of every dog’s diet, but it is especially important for active dogs that move a lot, as well as for breeding dogs. It matters a great deal what form of vitamin E your dog is getting.
Vitamin E is a collective name for various tocopherol and tocotrienol compounds, which exist in alpha, beta, gamma, and delta forms. These forms differ from one another in absorption, structure, and metabolism. The main differences between products are generally whether the vitamin E is natural or synthetic, and also what form it is provided in. Natural vitamin E is RRR-alpha-tocopherol and d-alpha-tocopherol, and synthetic is dl-alpha-tocopherol. The natural form is the most biologically active, and it integrates into the cell membrane to slow damage. Synthetic vitamin E is not as effective in the body as natural vitamin E. Studies have shown that the bioavailability of natural vitamin E is superior, at least 1.5 times that of the synthetic form. Natural vitamin E is reliably put to use in the horse’s body.
The form of vitamin E
Another important factor, in addition to the difference between natural and synthetic, is the form in which vitamin E appears in the product. Vitamin E can be difficult to keep stable, and for that reason it is often converted into the so-called acetate form to improve shelf life. The acetate form must be converted in the intestine into a usable form before it can be absorbed from the gut. First, the ester must be removed from the acetate form, and after that the body must make the acetate form water-soluble with the help of bile salts. For this reason, synthetic or acetate-form vitamin E must be given in a larger amount than natural, non-acetate vitamin E.1 Natural vitamin E is transported by a specialized transport protein as well as by chylomicrons. This transport protein also carries synthetic vitamin E, but not as efficiently as it carries natural vitamin E.3 Vitamin E is also transported on red blood cell membranes.4 For this reason, it is worth paying attention to what kind of vitamin E you buy—natural vitamin E that is not in acetate form is absorbed most efficiently.
Vitamin E has many important functions
Vitamin E acts as an antioxidant in the body. In this role, it supports the wellbeing of cell membranes and protects the horse’s body, intracellular compounds, and enzymes from the harmful effects of oxygen. Vitamin E also improves the absorption and storage of vitamin A in the body, and it contributes to DNA synthesis, immune system function, and hormone production.5 By participating in DNA synthesis, vitamin E also plays an important role in the horse’s reproduction.6 Vitamin E affects muscle tissue condition and energy production, and it increases resistance against equine influenza and tetanus. A deficiency of vitamin E can predispose a dog to muscle damage and lead to decreased performance.7 . Excess intake of vitamin E is not dangerous, and according to research it is the safest of the fat-soluble vitamins. Vitamin E has been shown to be safe even in large doses, but at excessively high doses it may interfere with the function of other fat-soluble vitamins.
Vitamin E is obtained from food primarily from plant-based sources, such as certain oils, nuts, grains, and fruits. Many dog foods have vitamin E added to them. Oils added to the diet are important to consider when assessing a dog’s vitamin E requirement, because higher oil intake increases a dog’s need for vitamin E.
Research references:
1 Turunen 2016
3 Waldridge 2017, 101
4 Aro et al. 2007, 151
5 Briggs 2007, 69)
6 Cuddeford 2003, 51
7 Saastamoinen et al. 2007, 19
8 Saastamoinen et al., 2007, 19
9 NRC 2007, 114
10 Autio 2015
