From foodconsumer.org
Dairy trans fatty acid reduces heart risk factors in rats
By David Liu, Ph. D.
Apr 2, 2008 - 6:47:47 PM
WEDNESDAY April 2, 2008 (Foodconsumer.org) -- It's known that dairy and beef products contain quite a high percentage of trans fat, which worry some people. A new Canadian study suggests that the dairy trans fat may actually reduce heart risk.
The study by researchers from the University of Alberta showed rats fed a diet with enriched levels of trans vaccenic acid (VA) lowered risk factors associated with heart disease, diabetes and obesity.
Trans vaccenic acid is a natural animal fat found in dairy and beef products. Some people fear that humans may not handle it well as the fat is intended for baby cows that have a digestive system different from humans.
Flora Wang, a Ph. D. candidate and professor Spencer Proctor found the possible benefit was due to the ability of VA to reduce the production of chylomicrons - fat and cholesterol particles that form in the small intestine.
Chylomicrons are viewed as important for conditions arising from metabolic disorders.
"Our results provide further evidence of the important role of chylomicrons in contributing to risk factors associated with metabolic disorders," said Wang.
"They also indicate a strong opportunity for using diets with enhanced VA to help reduce these risk factors."
The study includes two VA feeding trials, one lasting three weeks and the other 16 weeks, using model rats for obesity and metabolic syndromes.
Recently at the International Symposium on Chylomicrons in Disease, the researchers reported VA may have direct impact on the intestine and reduced key metabolic risk factors.
In the 16-week trial, total cholesterol, LDL cholesterol, and triglyceride levels were lowered in rats on a diet containing enhanced levels of trans vaccenic acid by about 30 percent, 25 percent and more than 50 per cent respectively.
Dairy and beef products contain trans fat of which 70 percent is VA.
The results suggest that the natural dairy trans fat differs from harmful hydrogenated trans fat which is commonly used in food processing and has been linked to increased risk of heart disease.
"As the VA results illustrate, some natural trans fats are not harmful and may in fact be very good for you," Wang said.
A scientist affiliated with foodconsumer.org who was not part of the research team cautioned that people should not rush to eat lots of trans vaccenic acid for now because this study is not sufficient to demonstrate that long term-consumption of large quantity of dairy trans fat would do any good to humans.
It was unknown the overall health status of the tested rats and at what age the rats were tested. It's also not clear how early consumption of VA would affect heart health in later life of rats.
He said more research is needed to clarify a number of issues. One issue need to be clarified is how humans metabolize trans vaccenic acid. Just because the trans fat can reduce cholesterol levels does not necessarily mean it can definitely reduce risk for heart disease.