(crossposted)

THE PET NUTRITION CORNER
By Wendy C. Brooks, DVM, DipABVP
Educational Director, VeterinaryPartner.com


Diet and the Skin

Did you know that skin diseases account for as much as 25% of the cases seen by small animal veterinarians? Skin problems typically faced by pets and their owners include:

itching
dandruff
blackheads
odor
crusting
redness
rashes
oiliness

The nutritional aspect of skin disease is a very broad topic, too broad to address in this small article. There are true nutritional deficiencies which affect the skin and other skin diseases that can be made dramatically better through the use of supplementation.

It is helpful to know that because a condition responds to a nutrient, this does not necessarily mean that a deficiency of that nutrient is present.

Everyone wants their pet to have a lustrous beautiful coat and would like to do what is nutritionally possible to ensure this. Recently essential fatty acids have received a great deal of press. A brief primer follows.

WHAT IS A FATTY ACID?

Biochemically, a fatty acid is what we colloquially refer to as fat. When we talk about different types of fatty acids we are talking about different types of fat. A fatty acid consists of a long carbon chain (say 20 or so carbons in length) with a biochemical acid group at one end.

SATURATED VS. UNSATURATED

Each carbon has four binding sites. In the carbon chain, two sites will be taken up by other carbons (i.e., the two adjacent carbons on the chain). In a saturated fat, the other two sites are taken up by hydrogen atoms. Saturated fats are typically solid at room temperature (like lard and butter) and are generally of animal origin. Saturated fats are generally burned as fuel by our bodies.

Unsaturated fats have two adjacent carbons held together by a biochemical double bond. These fats are generally liquid at room temperature and are of plant origin (olive oil, corn oil etc.).

Unsaturated fats can be classified as omega three fatty acids or omega 6 fatty acids, depending on the location of the double bond relative to the end of the chain. These types of fatty acids are essential, meaning that our bodies cannot make them; instead, in order to get them we must eat them in our diet. These fats are not burned for fuel. Instead they are used as structural components. The omega 6 fatty acids are used as the main structural components in our cells. Omega 3s are used in the structure of the retina and central nervous system.

For healthy skin and coat, the diet must contain adequate omega 6 fatty acids, as these make up the very surface of the skin.

Examples of omega six fatty acids (also called n-6 fatty acids): Linoleic acid, gamma linolenic acid, and arachidonic acid

An excellent source would be evening primrose oil

Examples of omega three fatty acids (also called n-3 fatty acids): Alpha linolenic acid, eicosapentaenoic acid, docosahexanoic acid

An excellent source would be cold water fish oils

SHOULD WE SUPPLEMENT ESSENTIAL FATTY ACIDS?

There is no question that a diet must contain adequate omega 6 fatty acids to maintain optimal skin and coat quality. A complete and balanced diet has an amount of omega 6 fatty acids that should be optimal for a normal animal.

But there's more. Research has shown that dogs with seborrhea (oily, dandruffy skin) have depleted amounts of omega 6 fatty acids in their skin despite eating a diet that should be optimal. When omega 6 fatty acids are supplemented, the seborrhea improves. This finding supports the old time remedy of adding a spoonful of corn oil to the diet to ensure a glossy coat. It should be realized that seborrhea is complex condition but animals with seborrhea may need more omega 6 fatty acids.

And still more. Omega 6 fatty acids constitute our cell membranes. During assorted biochemical situations it becomes necessary to produce hormone-like substances called prostaglandins and leukotrienes. These substances are actually made from omega 6 fatty acids and the prostaglandins and leukotrienes that result are not necessarily good for us. In fact, these substances are responsible for itching, and inflammation leading to the clinical skin problems listed above. One way to address this, is to supplement omega 3 fatty acids which become incorporated into cell membranes along with the omega 6's. After a couple of months of supplementation, omega 3 fatty acids have infiltrated cell membranes significantly. When it comes time to make prostaglandins, the omega 3's are mobilized instead of the omega 6's only in this case, the prostaglandins that result are not inflammatory. When omega 3 fatty acids are supplemented, itching can be substantially reduced.

One problem with this is that no one really knows how much omega 3 fatty acid to supplement. There is some evidence that a ratio of omega 6 to omega 3 fatty acids in the supplement is crucial. If this is so, clinical research becomes hugely complicated as the diets of pets cannot be standardized easily for study. If pets in a study eat different diets, then it is impossible to tell what overall omega 6: omega 3 ratio each is receiving. Essential fatty acids are being pursued as treatment for diseases of virtually every organ system; watch for new research developments in this area.