Vitamin E, A, and D belong to the fat-soluble vitamins. Fat-soluble vitamins are named so, because the body absorbs them with fat. The body can also store them in the liver or fat tissue and, unlike water-soluble vitamins, fat-soluble vitamins do not need to be consumed every day. Instead, a larger portion than the daily requirement of fat-soluble vitamins can be consumed, once a week – for example, and the body can then draw from that reserve daily, as needed. Water-soluble vitamins, in comparison, need to be a part of the diet every day, because amounts beyond the body’s immediate need are excreted again.
Vitamins are essential to health. Lower than optimal levels of vitamins in the body can prevent optimal health. Absence of vitamins will lead to disease. Vitamins have diverse biochemical functions. Some, like Vitamin E, function as antioxidants. Others, like Vitamin A regulates cell and tissue growth and differentiation, or, like Vitamin D, have hormone-like functions as regulators of mineral metabolism.
In the need for fat-soluble vitamins, the cat is unique. Unlike other animals and subsequent to its adaptation as carnivore, it is dependent on preformed Vitamin E, A and D from animal tissue. It can not use carotene as a Vitamin A precursor and can not synthesize Vitamin D from the sun. It also appears to have a greater need for dietary Vitamin E, possibly due to the high iron content in its diet and elevated levels of polyunsaturated fatty acids – which includes all the essential fatty acids.
Both, Vitamin A and D can be toxic, over time, when the diet contains too much of it, because an excess of these vitamins are not excreted. However, it appears that the cat has some resistance to Vitamin D toxicity, and can consume 100 times the proposed adequate intake of Retinol (Vitamin A) before showing signs of illness from toxicity. Vitamin D and A toxicity, also known as Hypevitaminosis, result in severe illness with irreversible effects. Although the cat appears to have a greater needs of these vitamins for good health and appears to be more tolerant to elevated levels of these vitamins than other animals would, it is under no circumstances advised or suggested that over-supplementation with these vitamins is in any way safe for the cat.
Vitamin E appears to be least toxic of the fat soluble vitamins, and an excessive intake appears to have the greatest influence on inhibiting the functions of Vitamin D and K. Vitamin K is another fat-soluble vitamin, and plays an important role in blood clotting. Excess intake of Vitamin E has, therefore, been shown to reduce blood clotting.
Because Vitamin A and D are stored in the liver, the natural food source of these vitamins for the cat is the liver of its prey. Sources for Vitamin E are liver and fat of prey. Egg yolk contains appreciable amounts of Vitamin A, D, and E, because they are needed for the developing chick.
In the homemade raw meat diet, raw liver is the best and, should be, the primary source of Vitamin A and D. 100g of raw beef liver given once a week or divided into daily portions throughout the week would meet all of the cat’s dietary need for Vitamin A and D. Raw liver from other red meat species, like lamb or venison, will be comparable with beef liver in respect to Vitamin A and D content. Liver from poultry contains 35% less Vitamin A and D per 100g than beef liver, and more chicken or turkey liver must be fed per week to meet the cat’s need.
It is advised to supplement the homemade raw meat diet with vitamin E regardless of naturally occurring Vitamin E in the food.
All varieties of TCfeline premix are fortified with Vitamin E succinate (alpha-tocopherol), Vitamin A palmitate (Retinol), and Vitamin D3 (cholecalciferol). There are several reasons for this.
Many cat owners are seriously turned off by the idea of handling raw liver in the preparation of their cat’s food and won’t use raw liver although their cat’s life depends on it. Raw liver is also not a food that is always readily available at grocery stores. And then there are cats that simply will not eat raw liver or food that contains raw liver. Others would readily eat it, but are prompted, for reasons presently unknown, to regurgitate food containing raw liver.
For these reasons, I offer the TCfeline PLUS varieties which already contain liver in a dry form – either as dessicated beef liver or dessicated chicken liver. Both, vitamin A and D are very sensitive to oxidation and do not tolerate exposure to air and light. Analyses of the dessicated liver powders included in the TCfeline PLUS varieties revealed that only a fraction of the original amounts of Vitamin A and D in fresh liver remained after processing. Fortifying the premix with supplemental Vitamin A and D became, therefore, essential.
The TCfeline ORIGINAL formula, which does not include and liver in dry form but requires addition of fresh liver during preparation of the cat food, is also fortified with supplemental Vitamin A and D. The reasons for this are, that 100g of raw liver in a batch of cat food made with the premix is stretched over 10 days, when 100g of raw liver should be given to the cat over only 7 days (or every 7th. day). The recommendation to give 100g of liver to meet the cat’s need for Vitamin A and D also applies to beef liver. If liver from poultry is used instead, naturally occurring amounts of Vitamin A and D will not suffice. In addition, errors on part of the premix user may occur, and the TCfeline ORIGINAL may be used without any addition of raw liver at all. Unless the premix is fortified with at least the minimal of Vitamin A and D required by the cat, the cat would suffer deficiencies. Cat owners may also be forced to omit any kind of liver, because the cat will otherwise not eat the diet or be more prone to regurgitating it.
All TCfeline raw diet premix varieties are equally fortified with vitamin E to assure that it is well supplied with this essential antioxidant. In the case of Vitamin E, we are not relying on any natural food source, although Vitamin E may be present in egg yolk, and some in liver and the fat in meat.
The amounts of Vitamin E succinate, Vitamin A palmitate, and Vitamin D3 used to fortify all varieties of the TCfeline premix are completely safe regardless of additional Vitamin E, A, and D supplied from some food stuffs in the diet, namely raw liver and raw egg yolk. In the case when raw liver and raw egg yolk is omitted, the fat-soluble vitamins with which the TCfeline premix is fortified with are essential.
It is not recommended to supplement the cat food made with the TCfeline premix with more vitamin A, D, or E in the form of tablets, capsules, gel caps, oils, or from more raw liver unless suggested by a Veterinarian for therapeutic purposes.