Artificial trans fats are bad for you, but naturally occurring ones may have very different effects.
A diet with enriched levels of trans vaccenic acid (VA) — a natural animal fat found in dairy and beef products — can actually reduce risk factors associated with heart disease, diabetes and obesity, according to a researcher from the University of Alberta.
The benefit was due in part to the ability of VA to reduce the production of chylomicrons, which are particles of fat and cholesterol that form in your small intestine following a meal. They are then rapidly processed throughout the body, and may be related to a variety of conditions arising from metabolic disorders.
Experiments on rats showed that VA in the diet could lower total cholesterol by approximately 30 percent, LDL cholesterol by 25 percent, and triglyceride levels by more than 50 percent.
Science Daily April 5, 2008