Doctors, Dietitians Stand Behind Fat/Cancer Link

Most physicians and diet experts applaud a new report linking diet to cancer.

Oct. 31, 2007 — -- Thinking about eating that extra slice of bacon for breakfast? Think again, cancer experts say.

A new study released today by the American Institute for Cancer Research (AICR) and the World Cancer Research Fund finds convincing evidence that excess body fat as well as consumption of alcohol, red meat and processed meats like bacon increase your risk of developing cancer.

The report, titled "Food, Nutrition, Physical Activity and the Prevention of Cancer: a Global Perspective," says that excess weight increases your risk of developing six different cancers. It also contains stringent guidelines regarding weight, diet and exercise to help reduce that risk.

"The news and conclusions are important because they help confront the view that cancer risk is something we don't control," said Dr. David Katz, director of the Prevention Research Center at the Yale University School of Medicine in New Haven, Conn. "In my experience, patients tend to recognize that they can control their heart disease risk, but they think of cancer as a bogeyman that pounces from the shadows … that isn't so.

"Along with avoiding tobacco, weight control and certain dietary adjustments offer powerful means of reducing risk for many, perhaps most cancers."

And although this link between obesity and cancer is not new, the new report adds a wealth of data to the existing research and condenses more than 7,000 different research papers into one comprehensive statement.

"What's new about this report is that a panel of distinguished scientists from around that world reviewed findings from multiple studies, and when we added them all together we found that excess body fat increases risk of developing cancer," said Dr. Steven Zeisel, director of the Nutrition Research Institute at the University of North Carolina and expert on the AICR panel.

Specifically, researchers found convincing evidence that excess body fat increases risk for colon, kidney, pancreatic and postmenopausal breast cancer as well as cancer of the esophagus and endometrium.

Not only do experts recommend that people stay within the healthy weight range throughout adult life, but they further stipulate that people should stay as lean as possible within that range. Avoiding energy-dense foods that are high in fat, such as burgers, french fries and milkshakes, as well as exercising at least 30 minutes each day, can help.

"We analyzed over 500 studies and found that it is highly probable that being fat increases your risk of developing a number of cancers," said Zeisel. "Every increment of being leaner reduces your cancer risk."

Other Factors Still at Play

However, experts do warn that people should not take this message to the extreme.

"I wouldn't want people to get obsessed about having as little body fat as humanly possible," said Keith-Thomas Ayoob, an associate professor of pediatrics at the Albert Einstein College of Medicine in Bronx, N.Y. "There's still room for some favorites and even some treat food -- it should just be less often and in smaller amounts. I'm still going to have my ounce of dark chocolate every day."

Experts also emphasize that smoking, not diet, is the primary risk factor that people can address to reduce their cancer risk.

"From a global public health perspective, it is tobacco, not diet that is projected to be the driving force in increased cancer deaths," said K. Michael Cummings, chairman of the Department of Health Behavior at the Roswell Park Cancer Institute in Buffalo, N.Y. "Avoiding tobacco, the green leafy vegetable that is not good for you, will prevent about 30 percent of cancers."

But if you don't smoke, diet and exercise are the next most important factors to control.

"There's no question -- if you don't smoke, the most important lifestyle change you can make to reduce your cancer risk is to strive to maintain a healthy weight," said Colleen Doyle, director of nutrition and physical activity at the American Cancer Society. "Being physically active is important not only to help maintain a healthy weight, but also directly impacts the risk of breast and colon cancer."

Taking a Cut at Meat

In addition to maintaining a healthy body weight, the AICR report urges people to limit their consumption of red meat -- a statement the American Meat Institute has already called "extreme and unfounded."

According to the report, there is evidence that red meat, including beef, pork and lamb, as well as processed meats such as bacon, ham and sausage, significantly increase the risk of colorectal cancer.

Researchers say for every 1.7 ounces of red meat and processed meat consumed each day, cancer risk increases by 15 percent and 21 percent respectively. Researchers recommend only eating 18 ounces of cooked red meat per week and avoiding processed meat altogether.

Instead of meat, researchers say fruits and vegetables should be the main course, a statement that Doyle agrees with.

"Eat plenty of vegetables, fruits and whole grains, and limited amounts of red and processed meats," she said.

Besides food, alcohol consumption may increase your cancer risk as well. The AICR panel found that alcoholic drinks are linked to mouth, larynx and colorectal cancers and may also cause liver cancer. The report said men should limit alcoholic intake to two drinks a day and women to one.

Recommendations May Extend to Other Nations

Although the report is particularly relevant to those in the United States, the recommendations regarding diet and exercise can help people make healthy choices around the world.

"What is most remarkable about this effort, though, apart from the completeness of the review, is the international approach. I was pleasantly surprised to find that the 10 recommendations seem to resonate with needs and opportunities in diverse parts of the world, from India to Mexico to Sweden," said Dr. Tim Byers, a professor of preventive medicine and biometrics at the University of Colorado and an expert on the AICR panel.

"The developed and developing nations alike all face similar problems with obesity, physical inactivity, limited food choices, etc. So I think this report will be seen as an important step towards developing international consensus and collaboration on efforts to reduce chronic diseases through improved nutrition."