Harvard Health Letter
There’s no guarantee you can prevent cancer, but you can reduce the risk of developing it by making lifestyle changes.
Cancer is a complex group of diseases, each characterized by the uncontrolled growth of previously normal cells. While cancer is complex, reducing your risk for it isn’t nearly as complicated: it boils down to healthy living.
“Of course, maintaining a healthy lifestyle requires behavioral change, and for many people, that means work,” says Dr. Beth Overmoyer, an oncologist at Harvard-affiliated Dana Farber Cancer Institute.
If you’ve been thinking of healthy living as “work,” then it’s time to put it at the top of your to-do list. There are no guarantees in life, and preventing cancer is no exception. But while lifestyle changes may not guarantee that you will never get cancer, there is no question that they will reduce your risk.
1. Lose weight
For most cancers, the risk is higher in people who are overweight, according to Dr. Overmoyer, because of effects on hormones and changes in the immune system.
Since being overweight boosts cancer risk, can the reverse be true—that is, can you reduce your risk of cancer by losing weight? “Yes, absolutely, we have evidence that if you maintain a normal body mass index you will reduce your risk,” says Dr. Overmoyer. A healthy body mass index (BMI) score falls anywhere from 18.5 to 24.9. You can determine your BMI with a free online calculator at health.harvard.edu/BMI.
Don’t turn to fad diets to shed pounds. Work with a dietitian to determine your target weight, the number of calories you’ll need each day, and an eating plan that you can sustain.
Getting aerobic exercise is another way to lower your cancer risk. And that’s true even if the regular exercise does not cause you to achieve a healthy weight. “The studies consistently suggest that cancer risk and cancer recurrence are reduced by up to 50% if you get enough aerobic exercise,” says Dr. Overmoyer. That may be because aerobic activity changes your metabolism; reduces inflammation, fat, and insulin resistance; and helps you control weight.
How much exercise do you need to reduce your cancer risk? Over all, the American Cancer Society recommends at least 150 minutes (2.5 hours) per week of moderate-intensity activity, such as brisk walking. “For breast cancer, it’s three to five hours per week,” says Dr. Overmoyer.
3. Eat a healthy diet
While we know there’s a link between red meat and colon cancer risk, no foods are proven to cause cancer. “Not even sugar,” says Dr. Overmoyer. “The link between food and cancer is the excess weight, and eating unhealthy foods can add pounds quickly.”
On the flip side, are there foods that can definitively prevent cancer? The evidence is mixed. Most experts recommend a diet containing foods rich in the vitamin folic acid (particularly if you drink alcoholic beverages regularly) and in vitamin D, and that minimizes red meat, processed meats, and excess calories. Dr. Overmoyer suggests having no more than two servings of red meat per week, and adds that “a diet full of fruits, vegetables, and whole grains has many phytochemicals, enzymes, fiber, and vitamins that all work together to fight many chronic diseases.”
4. Stop smoking
Toxins in tobacco smoke can damage your DNA. “That raises the risk for cancers of the lung, tongue, mouth, larynx, bladder, and cervix,” says Dr. Overmoyer.
But the great news is that quitting smoking will reduce the risk of developing cancer. The CDCreports that five years after quitting, the chance of developing mouth, throat, esophageal, or bladder cancer is cut in half.
5. Limit alcohol
Excessive alcohol drinking—more than one drink per day for women, and one or two drinks per day for men—may hurt the body’s ability to absorb nutrients; it may damage DNA, proteins, and fats; and it may affect blood levels of estrogen. It’s associated with many types of cancer, including head and neck, esophageal liver, and colorectal cancers.
Breast cancer appears to be especially sensitive to alcohol consumption. “The risk starts after four drinks per week,” says Dr. Overmoyer. If you must drink, drink only in moderation, and speak to your doctor about any drinking if you have concerns about developing cancer.