Written by Dr. Jill Cline, Ph.D.
Fatty acid nutrition has received a great deal of attention in recent years. In addition to having a requirement for certain essential fatty acids, dogs and cats may also benefit from the inclusion of certain types of omega-3 fatty acids in the diet. Understanding fatty acids and their functions helps owners to select the best food for their pet’s stage of life and health needs.
What are Essential Fatty Acids?
Fatty acids are components of triglycerides, a primary form of fat that is found in foods. Fatty acids provide a concentrated source of energy and have important roles in skin health, immune system function and neurological development. A group of select fatty acids also provide substrate for the production of cellular compounds that function in maintaining cellular health, proper blood clotting and the body’s normal inflammatory response. Although there are more than 70 different fatty acids that function in the body, dogs and cats (like humans) are capable of producing the majority of these and do not require a dietary source. The essential fatty acids are those that an animal cannot produce in sufficient quantities and must be provided in the diet. Dogs have a dietary requirement for just one fatty acid, linoleic acid, while cats require two; linoleic acid and arachidonic acid. When they are supplied at proper amounts in the diet, dogs and cats use these essential fatty acids to produce all of the other fatty acids needed by the body.
Omega-3 and Omega-6 Fatty Acids
The term “omega’ refers to the way in which fatty acids are classified. Every fatty acid consists of a chain of carbon atoms linked together with single and double bonds. Each fatty acid has a unique number of carbons and double bonds. Omega-3 fatty acids are fatty acids that have the first double bond located at the third carbon in the chain, while omega-6 fatty acids have the first double bond located at the sixth carbon. Although this seems rather arbitrary, it is quite important physiologically. Because their basic structures differ, the body’s use of dietary omega-6 and omega-3 fatty acids to produce regulatory I think a different word would be better. Regulatory isn’t a word they consumers understand in reference to body functions…in my oponioncellular compounds results in two different classes of derived compounds. In other words, when a dog or cat consumes a diet containing omega-3 fatty acids, all of the subsequent fatty acids produced in the body from those omega-3 fatty acids differ (sometimes in important ways) from the fatty acids and regulatory compounds that are produced from the omega-6 fatty acids in the food. Ultimately this means that feeding diets with different levels of omega-3 and omega-6 fatty acids affects the types of fatty acids and derived compounds that are functioning in your pet’s body.
The two essential fatty acids (linoleic acid and arachidonic acid) are both omega-6 fatty acids. If the diet is deficient in these essential nutrients, fatty acid deficiency signs develop. These signs include impaired growth, skin lesions and dermatitis, and hair loss. Dietary sources of omega-6 fatty acids include animal fats and some types of grains. Although no omega-3 fatty acids have been proven to be dietary essentials, there is increasing evidence that certain omega-3 fatty acids are needed to support fetal development and health throughout life. Fish oils and some terrestrial plant grains provide a rich source of omega-3 fatty acids (Box 1).
Long Names, Long Chains – Important Functions
The omega-6 and omega-3 fatty acids that are of greatest importance for your pet’s health are all long chain polyunsaturated fatty acids. This means that they are comprised of many carbons (18 or more) and that their carbon chains include two or more double bonds. Along with their long chains, these fatty acids also tend to have long names; for this reason it is often helpful to use abbreviations. Linoleic acid (LA) is used by the body as an energy source, maintains skin integrity by regulating water loss, and serves as a primary source for the production of arachidonic acid (AA) in dogs (remember – cats require AA in their diets). Arachidonic acid has many roles in the body that include skin health, immune health, cellular proliferation, and the body’s use of energy and fat. In addition, AA is found in high concentrations in brain and neural tissues and is essential for both normal development of the brain and for the maintenance of brain cells throughout life. Once AA is incorporated into the cell memebrande, a group of compounds called eicosanoids are produced which Finally, a group of compounds, called the eicosanoids are produced from the AA that is incorporated into cell membranes. These eicosanoids have essential roles in blood clotting, alterations in blood flow and blood vessel constriction, smooth muscle constriction and relaxation, and inflammation. Together, the functions of the various AA-derived eicosanoids promote the normal balance of responses that the body uses to react to foreign substances and to combat cellular injury.
The two long-chain (and long name!) omega-3 fatty acids that are most important are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). There is a great deal of recent evidence that DHA is an essential fatty acid that is needed for normal vision and neural development. EPA is important in ways that are similar to its omega-6 “counterpart”, AA. The EPA that is incorporated into cell membranes produces a series of eicosanoids that modulate the immune response. When compared with the eicosanoids that are produced from AA, those derived from EPA cause a relative reduction in the inflammatory response. It is this difference between EPA and AA that has led to the use of omega-3 fatty acids therapeutically in the management of certain types of inflammatory disease.
Finally, a third omega-3 fatty acid, alpha-linolenic acid (ALA), is occasionally used in diets. By itself, ALA does not have many important roles. However, animals are capable of converting small amounts of dietary ALA into EPA and DHA. For this reason, ALA is often promoted as an important source of omega-3 fatty acids. However, it is now known that adult animals are limited in their ability to convert ALA to the longer-chain omega-3 fatty acids. Studies show that only about 1 percent of ALA is converted to DHA in adult humans and dogs. Therefore, while adding ALA to a diet will increase the total omega-3 fatty acid content, it is not the best way to attain omega-3 benefits. The best source of omega-3 fatty acids are from EPA or DHA directly (such as from fish oils), rather than from their precursor, ALA.
Benefits of Omega-3 Fatty Acids
Omega-3 fatty acids have the potential to contribute to the health of dogs and cats during certain life stages and in the management of disease conditions that are associated with prolonged or uncontrolled inflammatory responses. Providing increased levels of omega-3 fatty acids aids in the reduction of the clinical signs of inflammation and contributes to a pet’s quality of life and vitality.
- Inflammatory skin disorders: Allergies occur when a pet’s immune system “over-reacts” to foreign compounds (antigens) in the environment. Providing omega-3 fatty acid supplementation to pets with atopy (allergies to inhaled substances such as pollens and molds) and other types of inflammatory skin problems has been shown to help to reduce itchiness and improve skin health.
- Osteoarthritis: Osteoarthritis is a chronic inflammatory disease that causes a pet’s joints to be painful and inflamed. Increasing the omega-3 fatty acids in the diets of arthritic pets can reduce signs of lameness and stiffness and may allow a reduction in dose or even discontinued use of the anti-inflammatory medications that are typically used to control discomfort and pain.
- Inflammatory intestinal diseases: Although the underlying causes of inflammatory intestinal diseases in dogs and cats are poorly understood, there is new evidence that along with modifying protein sources, increasing omega-3 fatty acids can contribute to reducing clinical signs and promote remission.
- Cancer: Diets that provide omega-3 fatty acids from fish oil have been shown to enhance the effects of chemotherapy and contribute to wellness and quality of life in cancer patients. There is also some evidence that omega-3 fatty acid supplementation may slow the development and progression of certain forms of cancer.