A new study on the link between cancer and diet has found a strong and clear linkage between obesity and the risk of developing cancer.

A team of international scientists has found that up to 20% of cancers in women and 15% in men are caused by people being overweight.

The researchers have issued a list of recommendations for reducing the risk of cancer. It sounds like tough advice: avoid bacon, ham and other processed meats, exercise every day, do not put on any weight after the age of 21 and severely limit your alcohol intake.

Professor Martin Wiseman is the director of the reporting team at the World Cancer Research Fund.

"There's little doubt that alcohol is a cause of some cancers, and there doesn't seem to be, as far as we can tell, as specific level below which there is absolutely no risk, and a level above which there is some risk," he said.

Wiseman is unapologetic for the stern warnings, saying the review of 7,000 studies from around the world has shown more clearly than ever before that putting on weight significantly increases the risk of developing cancer.

Professor Walter Willett from the Harvard School of Public Health was on the 21-member panel, which came up with a total of 10 recommendations.

"The relation we find between obesity and cancer is very strong: in fact probably about 20% of cancer deaths in women and 15% in men are due to overweight or obesity," he said.

Keeping Weight Down
Willett says the advice for people not to get any heavier than they were at 21 might seem like a tough ask, but it should not be.

"In our culture, that's become the reality, but in many other cultures -- for instance in Japan until very recently - women did not, on average, gain any weight after age 20, in fact, they declined a little bit," he said.

"So I think it's very possible. Similarly in Sweden, only 6% are obese as compared to about 34% in the U.S., so we can see other places where it's not out of control like it is in so many countries."

Willett says bacon and ham are not very safe foods in terms of cancer risk.

"It will quite clearly increase the risk of colon cancer, so, if you're trying to keep your cancer risk low, it's good to really have those kinds of foods not very often," he said.

Smoking is still the number one cause of cancer, but the scientists say that because in many countries there are now more people who are overweight than who smoke, obesity is not far off in terms of overall risk.

Report Reactions
The Australian meat industry has taken exception to the findings, saying the scientists have simply got it wrong.

The results have angered David Thomason, the general manager of Marketing at Meat and Livestock Australia.

"The report just doesn't make sense, red meat consumption has been falling in Australia, it's down by 20% in the last 20 years, yet colon cancer rates have increased," he said.

"So to suggest that red meat is a significant cause of colo-rectal cancer is just flying in the face of common sense.

"Our scientists tell us that the things that the community should be focusing on is obesity, lack of physical exercise and excessive alcohol intake."

Thomason does agree with the scientists that processed meats should only be consumed in small quantities.

However, he says that finding is not particularly relevant in the Australian context.

"Australians are not great consumers of processed meats -- our consumption levels are less than half that of the Europeans, on which many of these recommendations are based," he added.

"We eat most of our meat in fresh form, so from Australian perspective we'd encourage people not to get spooked by this report, there is really nothing to worry about."

From the November 5, 2007, Prepared Foods e-Flash