MONDAY, Jan. 27, 2003 (HealthDayNews) -- Want more proof that dogs are our best friends?
New canine-based research may answer how a type of fat found in deep-fried foods commonly served at fast-food restaurants affects childhood development and the potential for diseases such as atherosclerosis.
The fats are called oxidized lipids. They're unsaturated fats that undergo change after prolonged exposure to heat and/or oxygen. Oxidized fats are found in oils that are used over and over for deep fat frying, according to the study, which was led by researchers at Purdue University.
Oxidized fats are believed to damage the lining of blood vessels, leading to an increased risk of atherosclerosis, a buildup of plaque in the arteries.
"We know that eating diets high in oxidized fat contributes to atherosclerosis and other diseases in people," John Turek, a cellular biologist at Purdue's School of Veterinary Medicine, said in a statement.
"But we don't know the long-term effects of foods high in oxidized lipids fed during the growth stage," he said. "Will organ and tissue growth be compromised? Will children develop geriatric diseases at an earlier point in their lives?"
To try to determine those long-term effects, the researchers fed coonhound puppies a highly oxidized lipid diet, and found the dogs had reduced growth, bone formation and immune function.
The same was true of puppies fed diets with moderate levels of the fats.
The study appears in the January issue of The Journal of Nutritional Biochemistry.
It's the first study in dogs to assess the impact of diets laced with oxidized lipids.
"In our society today we eat a lot of fried foods. For years, it has been felt that over-consumption of fried foods, which contain oxidized lipid products, could be detrimental to health," said Bruce Watkins, one of the study's authors and director of Purdue's Center for Enhancing Foods to Protect Health.
"What this study shows is that in a rapidly growing animal such as the dog, which parallels many of the ways in which we eat and our lifestyles as humans, there are some effects on immune function and bone growth, which could potentially be compromised with the eating of oxidized fat," Watkins said.
In their first few months of life, dogs grow rapidly, adding significant bone and lean body mass. In that way, they're comparable to children experiencing rapid growth spurts during puberty.
The 16-week study included 24 dogs, 2 months old at the start, who were divided into three groups. One group ate a diet of dog food with highly oxidized fat, one group ate dog food with moderately oxidized fat, and the third group ate dog food with low oxidized fat.
Other than the oxidation levels of fat, the dogs ate identical diets that provided all essential nutrients.
The dogs who ate highly oxidized fat gained less weight and had less body fat than the dogs in the other two groups. The dogs on the highly oxidized fat diet also had poorer immune function and a reduced rate of bone formation.
Their bodies also had less vitamin E, an antioxidant that counteracts the effects of free radicals, which damage protein, other lipids, DNA and cells, according to the study.
In terms of humans, this study reinforces what's been recommended for years -- limit the amount of fried foods you eat, Watkins said.
The level of oxidized fat in fast foods varies widely, depending on the restaurant, Watkins said. The amount of oxidized fat is also dictated by a number of factors, including how often the oil in a deep fat fryer is changed, how well the fryer is cleaned and how much water comes into contact with the frying fat, he said.
More information
Here's where you can learn more about the good and bad fats in your food. And here's where you can find the Center for Enhancing Foods to Protect Health.
