Whole milk, cheese and butter often are left on grocery store shelves by health-conscious consumers determined to keep fat out of their diets.

But Mark McGuire, a dairy professor at the University of Idaho in Moscow, said one component of animal fat may help prevent cancer, and dairy producers must stress such health benefits if they want to compete in today's food marketplace.McGuire spoke on the cancer preventative properties of milk during Friday's Utah Dairy Convention in Ogden.

His research has focused on conjugated linoleic acid, or CLA, a natural product in milk that has been shown to inhibit breast, colon, skin and other cancers in lab animals.

McGuire said a recent Finnish National Public Health study followed about 5,000 women over the course of 25 years. The study found that, as the women's intake of dairy products increased, their risk of breast cancer decreased.

"What this really shows is that dairy products do protect women against breast cancer," he said. "It just takes a minute amount of this stuff to prevent cancer."

CLA is formed when microbes in the rumens of cattle and sheep and in the guts of turkeys "conjugate," or chemically restructure, linoleic acid, which itself is an apparent cancer-promoter. University of Idaho information said CLA constitutes 2.5 percent of the fat in ground turkey, 4.3 percent of the fat in ground beef, 5.5 percent of the fat in homogenized milk, 5.6 percent of the fat in lamb and 6.1 percent of the fat in some cheeses.

Human bodies do not produce much CLA, McGuire said, but some health food stores and muscle magazines promote a CLA-containing product called Tonalin. The ads tout the product's ability to make people leaner.

"We have a competitor," he said, but dairy farmers and processors should emphasize the natural occurrence of CLA in their products.

"This is a message the dairy industry needs to get to the consumer," he said. "Drink whole milk. Don't be afraid to eat more cheese.

"We have an opportunity to take and promote our product for its healthfulness. We need to make sure the American public knows that to get a daily dose of this essential anti-carcinogen, they need to eat their dairy products."

McGuire said the industry would face regulatory battles if it tried to put "cancer-fighter" labels on dairy products. But individual farmers and processors can get the word out, he said.

They need to let consumers know that, although consuming too much fat is not healthy, milk and cheese should be on their grocery lists.

"The bottom line is, it is and should be an important part of the diet," he said.