It is not every day that a medical story hits the front page of USA Today, but today one has, and for a very good reason.
The World Cancer Research Fund (WCRF) has just published a report that we have been eagerly awaiting for several years. It is the most comprehensive analysis ever published on the link between cancer and diet, weight and physical activity. Researches at nine academic institutions across the world looked for every relevant study published since records began in the 1960s. They initially found half a million, and in the end 7,000 of them were judged to be the most relevant and robust for inclusion in the report.
It includes 10 recommendations from a panel of 21 world-renowned scientists that represent the most definitive and authoritative advice that has ever been available on how the general public can prevent cancer. UNICEF and the World Health Organization were among the official observers of the report's process.
A key finding is that maintaining a healthy weight (a BMI of 20-25) is one of the most important things you can do to prevent cancer. The number of types of cancer where there is "convincing" evidence that body fat is a cause has risen from one to six since the last WCRF report was published in 1997, including colorectal cancer and post-menopausal breast cancer.
Prof Sir Michael Marmot, who was Chair of the Panel, said that,
“We are recommending that people aim to be as lean as possible within the healthy range, and that they avoid weight gain throughout adulthood.
"This might sound difficult, but this is what the science is telling us more clearly than ever before. The fact is that putting on weight can increase your cancer risk, even if you are still within the healthy range.
"So the best advice for cancer prevention is to avoid weight gain, and if you are already overweight then you should aim to lose weight."
Other findings in the report include:
There is "convincing" evidence that processed meats, including ham and bacon, increase the risk of colorectal cancer. People who consume them are advised to do so sparingly.
The evidence that red meat is a cause of colorectal cancer is stronger than ever before. People should not eat any more than 18 ounces (500g) of red meat a week.
This figure is for cooked meat, and is the equivalent of between 15-30 ounces (700-750g) of non-cooked meat.
Here is something that is almost a first, at least for a cancer report. It has made a breastfeeding recommendation: mothers are advised to breastfeed exclusively for six months and to continue with complementary breastfeeding after that. This is because of "convincing" evidence that breastfeeding protects the mother against breast cancer and "probable" evidence that it protects the child against obesity later in life.
Dietary supplements are not recommended for cancer prevention. The evidence that alcohol is a cause of cancer is stronger now than ever before.
Professor Martin Wiseman, Project Director of the Report, said:
"This report is a real milestone in the fight against cancer, because its recommendations represent the most definitive advice on preventing cancer that has ever been available anywhere in the world.
"When individual studies are published, it is impossible for the public to put them into context and know how seriously they should be taking the findings. But the great thing about this report is that it does this job for them.
"If people follow our recommendations, they can be confident they are following the best advice possible based on all the scientific research done up to this point. These recommendations are not based on one study but are based on 7,000."
In the United Kingdom, plans are afoot to establish a Cancer Reform Strategy. Professor Mike Richards, the British Government's Clinical Director for Cancer, had this to say:
“The WCRF report is the most authoritative and exhaustive review done thus far on the prevention of cancer through food, nutrition and physical activity.
"For those of us wanting to lower our risk of developing cancer, the Report provides practical lifestyle recommendations. The Report also provides public health goals. Both will form an important element for the forthcoming Cancer Reform Strategy."
These are the main recommendations:
- Limit red meat
- Limit alcohol
- Avoid bacon, ham, and other processed meats
- No sugary drinks
- No weight gain after 21
- Exercise every day
- Breastfeed children
Have you seen those infomercials where someone tells you that there is some conspiracy by shadowy people who don’t want you to know the truth about diet, exercise and cancer? Next time remember this research. If some expensive supplement or the juice of an exotic berry from the Himalayas could really reduce the risk of cancer, these studies should have noticed something by now.