Vitamins and minerals are indispensable elements although they are needed in very small amounts.
Vitamins are categorized as:

• Fat-soluble: A, D, E and K
• Water-soluble: B-complex vitamins and Vitamin C

Le Fat-soluble vitamins that are provided in excess in the diet are stored primarily in the liver. The body is not, however, able to accumulate water-soluble vitamins in significant amounts: any excesses are eliminated in the urine.

• Fat-soluble Vitamins are potentially toxic when provided in excess in a food;
• B vitamin deficiencies are detected immediately when not provided in sufficient amounts in the diet.

Fat-soluble vitamins:

• Vitamin A: Indispensable for: visual processes, bone growth, reproduction, the integrity of the epithelial tissue. Food sources: liver, fish liver oil, milk, eggs. The precursors of vitamin A are the beta-carotenes contained in plant foods like alfalfa, corn, etc., but these are less important for dogs than for other animal species, including humans;
• Vitamin D: Includes a group of sterols that regulate the metabolism of calcium and phosphorus. Vitamin D3 is the most important form for omnivores and carnivores. Food sources: fish liver oil;
• Vitamin E: Its primary function is as an anti-oxidant since it interrupts the oxidation process by providing free radicals with electrons. Food sources: germs of grains, soybean seeds;
• Vitamin K: Vitamin K1 is found naturally in leafy greens such as spinach and cabbage while particularly rich animal sources include egg yolk, liver and some types of fish meal. Given its role in blood coagulation, it is needed in the diet to supplement the vitamin K synthesised by bacteria in the colon.

Water-soluble vitamins:

• Vitamin C: Cats and dogs can produce adequate levels of vitamin C. It therefore, does not seem to be an essential vitamin, although its addition to the diet can stimulate the immune system;
• Vitamin B1 or Thiamine: Important in the metabolism of carbohydrates. Food sources: lean pork, beef, liver, wheat germ, whole grains, legumes and yeasts;
• Vitamin B2 or Riboflavin: Important for the oxidoreduction processes of the cells. Food sources: egg, milk, offal, whole grains and yeasts;
• Vitamin PP or Nicotinamide: Is active in the metabolism of lipids, carbohydrates, and proteins. Food sources: meat, legumes and grains, although when contained in plant food it cannot be assimilated to a great extent;
• Vitamin B6 or Pyridoxine: Important for metabolising amino acids, glucose and fatty acids. The need for this vitamin increases when the amount of protein increases. Food sources: offal, fish, wheat germ and grains;
• Pantothenic Acid: Sources: found in all foods, but offal, egg yolk, dairy products and legumes are particularly rich;
• Biotin: Aids in the metabolism of fatty acids, non-essential amino acids and purines. Although it is contained in many foods, its bioavailability varies greatly. Food sources: egg (however, the avidin in the raw egg white binds with the biotin making it unavailable, although cooking decreases the activity of avidin), liver, milk, legumes and walnuts. Intestinal bacteria are able to synthesise it;
• Folic Acid: Is involved in synthesising DNA. Food sources: dark green leafy vegetables and offal. It is also synthesised by bacteria in the intestine;
• Vitamin B12 or Cyanocobalamin: Indispensable for myelin synthesis. Food sources: foods of animal origin.