Nutrition and lifestyle habits such as watching one's weight, exercising daily, breastfeeding after pregnancy and limiting alcohol intake could prevent an estimated 40 per cent of breast cancer cases in the U.S., according to a new report.

The American Institute for Cancer Research, a cancer charity, updated its 2007 review of more than 800 studies on the role of nutrition and lifestyle in cancer, adding findings on 81 studies.

"We estimate that almost 40 per cent of breast cancer cases in the U.S. — or about 70,000 cases every year — could be prevented by making these straightforward everyday changes," said the institute's director of research, Susan Higginbotham.

The report recommends:

• Doing physical activity for at least 30 minutes every day.
• Limiting consumption of alcohol to two drinks a day for a man and one for a woman.
• Breastfeeding exclusively for up to six months after a baby is born.
• Staying as lean as possible without becoming underweight.
• Avoiding sugary drinks and energy-dense foods.
• Eating more of a variety of vegetables, fruits, whole grains and legumes such as beans.
• Limiting consumption of red meats such as beef, pork and lamb and avoiding processed meats.
• Limiting consumption of salty foods and foods processed with sodium.
• Not using supplements to protect against cancer.
• Not smoking or chewing tobacco.

The report did not look at the role of hormones in breast cancer, including use of oral contraceptives and postmenopausal hormone therapy.

Inherited genetic mutations are also a risk factor for breast cancer, accounting for an estimated five per cent to 15 per cent of all breast cancers.

The cancer charity aimed to put new research into a meaningful context, said Marilyn Gentry, chief executive of AICR and the World Cancer Research Fund.

"Having a healthy lifestyle doesn't guarantee a woman won't get breast cancer, but it reduces her risk," said Dr. Alison Ross, senior science information officer for Cancer Research U.K., in a statement commenting on the report.

"If women attend screening and keep an eye out for any symptoms that could be breast cancer, they are more likely to pick up any early signs of the disease when treatment is most likely to be successful."

The report is published on the institute's website. Similar reviews are also underway for colon cancer and prostate cancer and are expected to be completed early next year.