Low-Carb Diet Research and News

By Liz Lynch
HealthSCOUT Reporter

FRIDAY, Sept. 22 (HealthSCOUT) -- A diet rich in olive oil may help stave off intestinal cancer.

That's among the new findings linking diet to colorectal cancer rates that come from analysis by number-crunchers and medical researchers at Oxford University in England.

Diets high in a combination of meat and fish have a higher cancer risk than diets that contain olive oil, they say.

Eating a lot of meat prompts the liver to step up production of a bile acid called deoxycyclic acid, the researchers theorize. This acid in turn reduces the activity of an enzyme that may regulate cell turnover in the intestinal lining, affecting the rate of abnormal cell production.

But olive oil seems to reduce the bile acid production and increase enzyme activity levels, they say.

That might explain why meat-loving nations such as Australia and the United States have far more colorectal cancer cases than Mediterranean countries, the researchers speculate.

And, they add, it also might explain why people from countries with lower colorectal cancer rates experience higher cancer rates if they migrate to meat meccas.

The researchers, from Oxford's health-care epidemiology department, tracked nutritional profiles and colorectal cancer rates in 28 countries, categorizing foods consumed in 1990 and meshing that information with colorectal cancer rates from 1987 through 1992. Statistical models helped them gauge the effect of a range of dietary variables on the cancer rates. Findings appear in the current issue of the Journal of Epidemiology and Community Health.

Crunching and cross-crunching the numbers, the researchers also concluded:

 

• Meat consumption was critical. When high amounts of meat were present in the diet, colorectal cancer risk stayed up, even when vegetables were added to the statistical mix. With or without cereals and vegetables in the diet, the study says, eating lots of meat poses an elevated risk.

   

• The protective effect of olive oil remains regardless of the amount of fruit and vegetables in the diet.

However, Harris Clearfield, a gastroenterologist at M.C.P. Hahnemann University School of Medicine in Philadelphia, says dietary factors in colon cancer -- intriguing as they are -- remain difficult to quantify.

"The standard teaching has suggested that a high-fiber, low-fat diet has protective value," Clearfield says. "There has been a great deal of commitment to this, but the hard data to show this to be the case is lacking."

Lately, prevention efforts have focused more on surveillance for polyps than on diet, he says. And while modifying diet for health reasons is valid, he says, it's a bad idea to think that eating right cancels out the need for those regular trips to the doctor's office for a colon check.

"The public should not be left to believe that they don't have to do these tests," Clearfield says.

What To Do

Don't go pouring olive oil over everything you eat, at least not yet. "It's too early for a study like this to have practical implications," says Melanie Polk, a registered dietitian and director of nutrition education for the American Institute for Cancer Research, in Washington, D.C.

Although a number of interesting observations have been reported about olive oil and its healthful effects, "it's important for us, not only as nutrition educators but as consumers, to tread carefully here because it is really the mass of research that matters, not individual studies," Polk says.

In the meantime, keep in mind that olive oil is still an oil, "and any kind of oil, olive oil included, is high in calories," she says. Monounsaturated oils -- such as olive oil and canola oil -- are still your best choices for oils, but use them in moderation, she says.

And don't neglect periodic medical screenings for colon cancer along with keeping an eye on your diet. Regular checkups are recommended for people 50 years and older, as well as for those with a family history of colon cancer.

For a wealth of information on your colon, consult this guide to intestinal health from the American College of Gastroenterology.

If you're worried about a family link to colon cancer, check out information on hereditary colon cancer from Creighton University's Hereditary Cancer Institute.

Or, you may want to read previous HealthSCOUT articles on olive oil.