NRC Essential Nutrients: Fat-Soluble Vitamins

Vitamin A (Retinol)

Vitamin A is a fat-soluble vitamin that is required for normal vision, growth, reproduction, immune function, and maintenance of healthy epithelial tissue functions. Vitamin A is also involved in the expression and regulation of many genes.

The National Research Council (NRC) for dogs and cats provides recommended and maximum amounts for Vitamin A per 1000kcal:

Vitamin A is found in animal tissues and the concentration in foods can be very greatly. Whereas carotenoids found in plant sources are absorbed half as well as Vitamin A from animal sources. Additionally, absorption efficiency decreases as carotenoids in the food increases. It is important to note cats can absorb β-Carotene but are unable to convert it to Retinol.

All raw diets consisting of 5% liver and other organs will provide the recommended allowance of Vitamin A. Be mindful of the amounts of Vitamin A in different liver proteins will vary greatly.

Wheatgrass and cod liver oil provide high amounts of Vitamin A. Cod liver oil is more concentrated in Vitamin A in comparison to other ingredients and is not recommended to use in a raw diet that includes raw liver. Wheatgrass provides Vitamin A in the form of carotenoids which are not nearly as bioavailable as animal sources of Vitamin A. 

Vitamin D

Vitamin D is a fat-soluble vitamin that has a primary function to enhance intestinal absorption and mobilization. It also plays a vital role in the retention and bone deposition of calcium and phosphorus.

The National Research Council (NRC) for dogs and cats provides recommended amounts for Vitamin D per 1000kcal:

Vitamin D3 (Cholecalciferol) is found in animal tissues and Vitamin D2 (Ergocalciferol) is found in plants. The absorption and metabolism of Vitamin D2 is less effective in dogs and more so in cats and are best utilized when provided from animal tissues.

Tocopherol is found in moderate concentrations within raw seeds and nuts and to a lesser amount in leafy greens. Animal tissue is low in Vitamin E, where the highest levels occur in fatty tissue. Some diets benefit from natural Vitamin E supplementation if whole foods do not supply adequate amounts within the diet.

Non-Essential, but Beneficial Vitamins

Vitamin K

Vitamin K is a fat-soluble vitamin that plays a major role in protein synthesization needed for blood coagulation and bone growth.

The National Research Council (NRC) for dogs and cats provides recommended and maximum amounts for Vitamin K per 1000kcal:

Vitamin K1 (Phylloquinone) is abundant leafy greens and Vitamin K2 (Menaquinone) is produced by intestinal microflora found in the colon.

Dogs and cats are able to microbially synthesize Vitamin K2 in the colon where dietary supplementation is unnecessary for most pets. However, this is not to suggest feeding foods with Vitamin K is not beneficial. Feeding leafy greens provides high amounts of Vitamin K and due to their high-fiber content, leafy greens also support fiber fermentation in the colon.