The importance of the B vitamins

01 August 2014, at 1:00am

Ian Williams in this eighth in a series from Royal Canin on up-to-date knowledge behind nutrients of bene t to dogs and cats looks at the bene ts of B vitamins in veterinary diets...

VITAMINS can be divided into two families: vitamins that are soluble in fats (liposoluble vitamins), namely vitamins A, D, E and K, and vitamins that are soluble in water (hydrosoluble vitamins), namely vitamins B and C.

In general, a balanced diet and additional synthesis by the intestinal bacteria guarantee a sufficient intake of B vitamins, although intake can become marginal in situations of major water loss. This is because of the water-soluble aspect of B complex vitamins and the fact that they cannot be stored.

Riboflavin (B2), niacin (B3), pantothenic acid (B5), pyridoxine (B6), inositol (B7) and biotin (B8) are all important for the quality of the skin barrier function. Deficiencies can lead to dry flaky seborrhoea accompanied by alopecia, anorexia, weight loss and pruritus. As an example, a deficiency in riboflavin can lead to head and neck alopecia, especially in cats.

Cats have high requirements in terms of water-soluble B vitamins and they are unable to convert β-carotene into retinol (the active form of vitamin A). This shows us that these companion animals are adapted to a carnivorous diet under natural conditions, since these vitamins are present in large quantities in animal tissues.

The skin barrier cocktail

The Waltham Centre for Pet Nutrition screened 27 substances that were thought to provide a beneficial effect on skin function. The selection criteria were based on limiting water loss through the epidermis and the synthesis of skin lipids. From this, the Centre identified four B vitamins and one amino acid acting synergistically to improve the barrier function of the epidermis and decrease trans-epidermal water loss. They were:

  • pantothenic acid which is involved as a co-enzyme in many metabolic pathways, including those of fatty acids;
  • inositol and choline which work together in the formation of cell membranes – combined with phosphorus, choline forms phospholipids;
  • niacin, which is synthesised from tryptophan, is essential for cellular respiration and also vital for a healthy and pliable skin;
  • histidine is essential for the growth and maturation of the epidermal cells (keratinocytes).

Together, this “PINCH” cocktail acts in synergy to promote the synthesis of ceramides (skin lipids necessary for the integrity of the outer layer of the epidermis). However, due to the time needed for the epidermal cellular differentiation process, these nutrients will only have a beneficial effect after approximately two months of administration.

Vitamin B12’s benefits

In addition to those B vitamins already mentioned, vitamin B12 is important for pets. It is involved in many essential biochemical reactions as a co-enzyme and plays a primary role in the synthesis of proteins and the production of red blood cells.

Also known as cobalamin, vitamin B12 is mainly found in animal products ( sh, meat and offal) and is very stable during the heat treatment of food products. It is the only vitamin to incorporate a mineral element in its chemical formula, namely cobalt.

Cobalamin plays an essential role in the synthesis of nucleic acids (in synergy with folic acid). A deficiency disrupts protein synthesis, especially for fast-regenerating tissues like haematopoietic tissue.

A fall in the body’s cobalamin reserves can be seen in cats and dogs suffering from issues with their pancreas or liver. The depletion of reserves may be explained by chronic dysorexia or intestinal malabsorption reducing the quantity of cobalamin available to the animal.

The deficiency may also be secondary to an insufficiency of intrinsic factor essential to the absorption of cobalamin. This glycoprotein is synthesised only by the pancreas, so impaired function of the pancreas is a risk factor for deficiency. Any imbalance in the intestinal bacterial ora is also likely to reduce the absorption of cobalamin, as intestinal bacteria use vitamin B12 and may also form connections to intrinsic factor.

Cats and dogs are not able to store large quantities of cobalamin in the body and they quickly become de cient when their homoeostasis is disrupted. Therefore supplementation of vitamin B12 is essential for the nutritional management of cats and dogs with impaired pancreatic or hepatic function.

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