Naturally occurring trans-fats vs artificial trans-fats

Trans fatty acids are found naturally in some foods and are formed during food processing; they are not essential in the diet. A number of studies have observed an association between increased trans fatty acid intake and increased risk of cardiovascular disease. This increased risk is due, in part, to its LDL cholesterol-raising effect. Therefore, Americans should keep their intake of trans fatty acids as low as possible.

Some trans fatty acids that Americans consume are produced by a process referred to as hydrogenation. Hydrogenation is used by food manufacturers to make products containing unsaturated fatty acids solid at room temperature (i.e., more saturated) and therefore more resistant to becoming spoiled or rancid. Partial hydrogenation means that some, but not all, unsaturated fatty acids are converted to saturated fatty acids; some of the unsaturated fatty acids are changed from a cis to trans configuration. Trans fatty acids produced this way are referred to as “synthetic” or “industrial” trans fatty acids. Synthetic trans fatty acids are found in the partially hydrogenated oils used in some margarines, snack foods, and prepared desserts as a replacement for saturated fatty acids. Trans fatty acids also are produced by grazing animals, and small quantities are therefore found in meat and milk products. These are called “natural” or “ruminant” trans fatty acids. There is limited evidence to conclude whether synthetic and natural trans fatty acids differ in their metabolic effects and health outcomes. Overall, synthetic trans fatty acid levels in the U.S. food supply have decreased dramatically since 2006 when the declaration of the amount of trans fatty acids on the Nutrition Facts label became mandatory. Consuming fat-free or low-fat milk and milk products and lean meats and poultry will reduce the intake of natural trans fatty acids. Because natural trans fatty acids are present in meat, milk, and milk products, their elimination is not recommended because this could have potential implications for nutrient adequacy.

--http://www.cnpp.usda.gov/sites/default/files/dietary_guidelines_for_americans/PolicyDoc.pdf

Rumenic acid, also known as bovinic acid, is a conjugated linoleic acid (CLA) found in the fat of ruminants and in dairy products. It is an omega-7 trans fat.

Vaccenic acid was discovered in 1928 in animal fats and butter. It is the main trans fatty acid isomer present in milk fat. Mammals convert it into rumenic acid, a conjugated linoleic acid, where it shows anticarcinogenic properties.

In lack of recognized evidence and scientific agreement, nutritional authorities consider all trans fats as equally harmful for health and recommend that consumption of trans fats be reduced to trace amounts.  http://en.wikipedia.org/wiki/Trans_fat

Comments:  There is no difference between "synthetic" and "natural" trans fatty acids.  They are naturally present in beef and milk.  I think that the "war on trans fats" is just part of the war on fat in general.  If you are going to ban trans fats then you have to ban beef and milk as well.  Maybe everyone should be forced to be vegetarians, as that would be healthier.