The process that forms oxidized lipids also occurs in the body's metabolic processes. Free radicals, a component of lipid oxidation, damages proteins, other lipids, DNA and cells, thereby causing disease. For this reason it's important to eat foods, such as fresh fruits and vegetables, which are low in oxidized lipids and high in antioxidants, Watkins said.

Though researchers have linked oxidized fat to several human diseases, most of the research was done in rodents. Young, growing dogs might give a better picture of how oxidized lipids affect humans, especially children during critical stages of development and growth, the scientists said. In the early months of life, dogs grow rapidly, adding considerable bone and lean body mass, which is more comparable to humans in rapid growth phases, such as puberty.

In the puppies, researchers found that those consuming highly oxidized fat gained less weight and had less body fat than their kennelmates that ate moderate- and low-oxidized fat diets, Turek said. The coonhounds on the diet high in oxidized fat also had decreased immune function and less vitamin E, an antioxidant that helps counteract the effects of free radicals. In addition, bone formation rate was reduced.

"Our study shows the need to control the amount of oxidized fats in food for both humans and companion animals so that we can ensure proper growth and optimum health," Turek said.

The 24 dogs, all 2 months old, were divided into three groups: One group ate a low-oxidized fat diet, one a diet with a moderate level of oxidized fat, and one a high oxidized fat diet. They were all kept on their assigned feeding regimen for 16 weeks. Other than the oxidation level of the fat, their diets were identical and contained all the other nutrients necessary for a healthy dog.

The oxidized lipid research is one of the ongoing projects by members of the Center for Enhancing Foods to Protect Health, of which Watkins
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Contact: Susan A. Steeves
ssteevees@purdue.edu
765-496-7481
Purdue University
15-Jan-2003