Exercise boosts energy, improves mood and promotes better sleep. But did you know it also can help prevent colon cancer? Research shows that even minimal amounts of moderate exercise reduces risk and dramatically helps those already diagnosed with the disease.
"In general, studies have shown lower cancer rates in those who are more physically active and have an exercise routine," says Dr. David Bodkin, a board-certified oncologist and hematologist affiliated with Sharp Grossmont Hospital.
Although the connection between physical activity and fending off colon cancer is certain, the exact reason is less clear.
"The belief is that exercise may be able to kill cancer cells. Your adrenaline gets going and that can lead to an increase in circulating NK (natural killer) cells," says Dr. Bodkin. NK cells are the body's frontline defense system; their job is to attack tumors and invading infections.
"Exercise increases antioxidant levels and DNA repair. It can also affect growth factor production and insulin metabolism in ways that reduce inflammation and increase immune function."
According to the National Cancer Institute, most physically active adults can reduce their risk of colon cancer by as much as 24%. And even moderate activity is beneficial.
"It's difficult to answer without specifics just how much activity is needed," he says.
"One Dana-Farber Cancer Institute (DFCI) study showed benefit with 150 minutes a week of moderate exercise, or 75 minutes a week of vigorous exercise. Workouts would have to be at least 10 minutes long and at least two sessions per week."
"Other studies have showed health benefit with as little as 20 minutes of exercise, three times a week, which seems reasonable," he says.
Another recently released DFCI report tracked 1,200 patients already diagnosed with colon cancer and found a 19% decline in risk for early death for those who did 30 minutes or more a day of moderate activity. Four to five hours of moderate activity, such as gardening, walking or light housekeeping, increased the benefit to 25%.
"This study is exciting. We know there's benefit in primary prevention and early-stage disease, but this study shows improvement can be extended to those with advanced cancer," he says.
"Physical activity can be difficult for this population. But even walking or yoga proved enough to show a response. Historically, these patients have felt the need to rest as their bodies are going through a lot. Now we know it's important to keep patients motivated to be active."
Beyond exercise and maintaining a healthy weight, Dr. Bodkin advises his patients to eat more vegetables, fruits and whole grains; minimize red meat consumption; avoid processed luncheon meats; not smoke; and limit alcohol to reduce risk.
"Awareness and screenings played a big role in decreasing colon cancer rates in the last 20 years. If you're over 50, get screened. And if there's a family history, communicate this to your health care provider," he adds.
This story was updated in March 2020.