Vaccenic Acid and Conjugated Linoleic Acid
Natural Trans Fats That Are Actually Good For You
Oct 13, 2009
In 1993 the Nurses' Health Study, an investigation involving more than 85,000 American nurses concluded that women who ate four or more teaspoons of margarine a day had more heart attacks than women who rarely ate margarine. The purpose of the study was to determine the correlation of dietary vegetable-oil based trans fatty acid intake with coronary heart disease. The results of the study confused and angered the public particularly those who had switched to margarine from butter. This led to other examinations aiming to explain the real nutritional and health impact of trans fatty acids.
Natural Versus "Man-Made or Commercial" Trans Fatty Acids and their Effects on Human Health
Natural trans fats are unsaturated fatty acids that are inherently present in the fat, dairy, and flesh of ruminant animals. Ruminant animals include cattle, sheep, goats, deer, moose, elk, caribou, bison and buffalo. Natural or native trans fats are formed by Butyvibrio fibrisalvens - an anaerobic bacterium that resides in the rumen of ruminant animals. The rumen is the the larger part of a ruminant animal's stomach. It is also the primary site of bacterial fermentation of ingested feed. The major natural trans fats found in butter, lard, suet, meats, and dairy products are:
- Vaccenic Acid (VA). It is produced by rumenal bacteria and is the primary trans fat in animal fat and meat.
- Rumenic Acid (RA) is also called omega -7. It is a conjugated linoleic acid and is the predominant trans fatty acid in bovine milk (70%-90%). Unlike vaccenic acid, rumenic acid is synthesized in the mammary glands of the animals.
Native trans fats are beneficial because:
- They decrease the body's production of chylomicrons - mixtures of fat and cholesterol that forms in the small intestines after a meal. Chylomicrons are rapidly processed by the body, but there are times when the body is overwhelmed and an overabundance of chylomicrons upsets the blood fat balance thereby increasing risks for obesity, diabetes, and heart disease.
- They inhibit certain types of cancer such as colon cancer and prevent the cancerous cells' spread (metastasis).
- They are believed to induce apoptosis (cell suicide by malignant cells).
- They prevent fat oxidation thereby inhibiting the body from producing free radicals - substances known to either initiate or hasten the progress of cancer once started.
By comparison, artificial trans fatty acids are unsaturated fatty acids that are formed during the "hydrogenation" of vegetable oils. By incorporating hydrogen into liquid vegetable oils, a semi-solid fat product is obtained. Food manufacturers favor man-made trans fats because unlike liquid vegetable oils, hydrogenized fats are more stable (less prone to rancidity). They extend the shelf-life of processed goods and improve "mouthfeel" increasing the products' sales. During hydrogenation the polyunsaturated fatty acids linoleic and linoleic acid are converted into elaidic acid - a trans fatty acid. It is the major trans fat produced by the hydrogenation process.
Commericial trans fats are closely associated with obesity, metabolic syndrome, diabetes, coronary heart disease and stroke because:
- They increase very low density lipoprotein cholesterol (VLDL-C) levels in the blood. VLDL is the forerunner of low density lipoprotein cholesterol (LDL-C) or "bad" cholesterol.
- They lower high density lipoprotein cholesterol (HDL-C) or "good" cholesterol levels in the body. HDL-C or "good" cholesterol picks up and removes excess cholesterol from cells and transports them back to the liver for recycling. It is this reverse cholesterol process that drops or normalizes blood cholesterol levels.
- They increase plasma lipoprotein (a) (Lp-a) levels. Lipoprotein a is a small fat molecule that has been implicated in coronary heart disease and stroke because of its ability to stimulate blood clotting and its high LDL cholesterol content.
Whole milk, dairy products, animal fat and meats have long traditions in human nutrition. For decades these food products have been unfairly associated with negative health effects. New research shows their contribution to our well-being. By incorporating modest amounts of these foods in our daily diet, everyone can once again benefit from their health benefits.
References
Wallace RJ et al. "Differences between human subjects in the composition of the faecal bacteria community and faecal metabolism of linoleic acid" Microbiology 2009;155:513-520
Wang Ye et al. "Trans-11 Vaccenic Acid Dietary Supplementatio Induces Hypolipidemic Effects in JCR-cp Rats" Journal of Nutrition November 2008;138(11):2117-2122
Haug A et al. "Effect of butter naturally enriched with conjugated linoleic acid and vaccenic acid on blood lipids and LDL particle size in growing pigs" Lipid Health Dis 2008;7:31
"Conjugated Linoleic Acid and Dietary Beef" Beef Facts: Human Nutrition Research National Cattlemen's Beef Association Website 2007
McGibbon AHK & Taylor MW "Composition and Structure of Bovine Milk Lipids" Advanced Dairy Chemistryedited by Fox PF & McSweeney PLA Springer New York 2006 pp:1-42
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