Monday, February 22, 2010

2/22/2010 - Omega-3's & Colic

Vet Tip of the Day: The role of Omega-3 Fatty Acids in Colic prevention
Key Words: Colic, Polyunsaturated fat, fatty acid, cell membrane, endotoxin

Since you are now budding experts on the subject of endotoxemia and its devastating effects on horses with gastrointestinal disease, I thought we would conclude this segment on colic with a discussion of Omega-3 fatty acids.  You've may have heard a lot of buzz about these special fats; following are some facts about Omega-3's and how they can help protect your horse from some of the terrible consequences of endotoxemia.

Omega fatty acids - What are they?

This part is pretty dry, but it will only last a few sentences, so hang in there. Our bodies derive four types of fat from food:cholesterol, saturated fat, monounsaturated fat, and polyunsaturated fat. Omega-3 fatty acids are polyunsaturated fats. They are called omega-3 because a certain chemical bond between two carbon atoms occurs at the third carbon in this fatty acid chain of carbons. The other major polyunsaturated fat in our diet is Omega-6 fatty acid (first double bond at the sixth carbon).

Omega-3 and Omega-6 fatty acids are considered “essential” fatty acids, because neither horse nor human can construct these substances internally. They must be obtained in our diets. While both O-3 and O-6 are necessary for good health, we and our horses eat diets that are relatively high in Omega-6 fatty acid and deficient in Omega-3. As we will see, it appears that an ideal ratio of dietary O-3 to O-6 is about 2:1, while most of us are eating these fatty acids in a ratio more like 1:10 or even 1:20.

Omega fatty acids - What is their function?

Consider the building blocks of our bodies. We and our horses are amazing machines, composed of a group of organ systems that works in harmony to create life. Each of our organs is a mass of cells, and each organ has its own distinctive cell type. Liver, kidney, skin, nervous tissue, brain, blood vessel walls - each has its own unique cellular architecture. However, all of these cell types are encased in the same basic cell membrane. Guess what our cell membranes are made of? You’re right - they are made of fat!

Cell membranes are composed of a double layer of phospholipid, a complex fat containing Omega-3 and Omega-6 fatty acids. The cell membrane is like a telegraph system; signals from outside the cell are communicated to the inside through the cell membrane. The composition of the cell membrane determines in large part how signals are translated from outside to inside; the cell membrane makeup greatly influences the cell’s response to a given stimulus. Specifically, a cell membrane enriched in Omega-3 fatty acids is protected from many of the inflammatory responses to injury that are produced by an Omega-6 enriched membrane. 

If your horse experiences a serious colic in which gut motility is disrupted, remember that this leads to a die off of bacteria normally present within the bowel.  Some of these bacteria contain endotoxin, which is absorbed into the blood stream through the compromised gut wall of your colicky horse.  This endotoxin attaches to cell membranes in your horse's system, sending a series of telegraph signals across cell membranes and from cell to cell that lead to the production of many small molecules responsible for inflammation, shock, and cardiovascular collapse.  If your horse's cell membranes are enriched with Omega-3 fatty acids, the severity of the inflammatory response to these signals is dampened, resulting in less devastating effects on your horse's circulatory system.

Omega-3 Fatty Acids - Where do we find them?

Omega-3 fatty acids are relatively abundant in oily, cold water fish such as tuna, salmon, and mackerel. These fish contain large amounts of two Omega-3's, eicosapentaenoic acid (EPA) and docosahexanoic acid (DHA). Vegetable sources of Omega-3's include kelp, as well as flaxseed, canola, walnut, and soy oils. The latter 4 oils contain alpha-linolenic acid (ALA) the third major Omega-3 fatty acid. One should remember that all of these sources of Omega-3 fatty acid also contain Omega-6 fatty acid. Once ingested, the Omega-3 and Omega-6 fatty acids compete for the same processing sites in the body, emphasizing the importance of the balance of O-3 and O-6 in the diet.

For us, consumption of Omega-3's is easily achieved by eating fish. Since 2000, the American Heart Association’s dietary guidelines have recommended that healthy adults eat at least two servings of fish per week. Alternatively, there are many encapsulated fish oils available: people with existing cardiovascular disease are encouraged to take 1 gram of EPA and/or DHA daily.

For our horses, there are an increasing number of supplements and concentrate feeds on the market that are enriched with flaxseed oil to supply Omega-3 fatty acids. Unfortunately, we have no good information on how much a horse should eat to achieve a beneficial result. Therefore, while there is mounting evidence that dietary enrichment with Omega-3 fatty acids will improve your horse’s overall well-being, we are still guessing with our dietary supplementation. One positive note concerning flaxseed oil, the primary source of Omega-3 for horse consumption: flaxseed oil contains three times more Omega-3 than Omega-6 fatty acid, making it likely to shift the overall dietary balance of O-3 to O-6 in the right direction, toward 2:1.

How will Omega-3's help my horse?

We may not know how much to feed, but we do have some experimental evidence concerning the beneficial effects of Omega-3 fatty acids in horses. In the laboratory setting, researchers have looked at the effects of Omega-3 fatty acids on various equine cell types. Cells from joint linings, or cells from the abdominal cavity, for instance, can be grown and maintained in the lab. The cell cultures, as they are called, represent miniatures of the whole horse. Each cell type can be “fed” diets containing varying amounts of Omega-3 fatty acids. Then, cells can be subjected to an experimentally induced injury and the cell’s response to this injury can be measured. In fact, a beneficial effect of Omega-3 fatty acids on equine intestinal cells has been demonstrated in this experimental setting.  The presence of Omega-3 fatty acids in the cell membrane reduces the cell's inflammatory response when exposed to endotoxin.
There is much left to be learned concerning the role of Omega-3 fatty acids in our overall health plan, for our horses and our selves. However, early evidence weighs in strongly in favor of a beneficial effect with no apparent associated dangers. Educate yourself more about the world of Omega-3 fatty acids and make an informed decision concerning the inclusion of an increased amount of this essential fatty acid in your horse’s diet.

A bit of trivia: who remembers the heart-rending movie Lorenzo’s Oil? The story of a child with a degenerative nerve disorder. Guess what the magic oil was? Right again - Lorenzo’s Oil was an Omega-3 fatty acid.

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