Among the myriad health risks raised by obesity, heart disease and diabetes are usually the first to come to mind. But as a paper published in last month’s Nature Reviews makes clear, fat also increases the risk of developing cancers of the colon, breast, uterus, kidney, esophagus, pancreas, gallbladder, liver and stomach. Among its conclusions, the review of more than 200 epidemiological sources suggests overeating may be the biggest avoidable cause of cancer in nonsmokers.
The extent to which weight makes a difference varies by the type of cancer and also by gender. Being overweight can mean up to two times the risk of developing colon cancer for men, while women’s risk is increased 20% to 50%. But the largest obesity-related cancer only affects women: A heavy woman has twice the risk — and an obese woman up to five times the risk — of developing uterine cancer than a lean woman.
Just how fat cells spur cancer growth is something scientists are only now beginning to figure out. “Fat cells are not just static storage depots,” observes American Cancer Society epidemiologist Eugenia Calle, co-author of the review. Complicating the picture is the fact that different kinds of fat cells spur tumor growth in different ways. The suspected mechanisms range from adipose-induced inflammation to overproduction of certain hormones to insulin regulation.
The good news is that unlike factors beyond our control — genetic predispositions to certain cancers, for example — obesity is largely preventable. A low-fat, complex-carbohydrate diet rich in fruits and vegetables has proven to be the most reliable and safest way to maintain a healthy weight over time. What’s more, the nutrients and fiber contained in fruits and vegetables are key to neutralizing cancer-causing free radicals.
Published September 27, 2004