What Causes, Prevents Colon Polyps
Vitamin D Shines in New Study; Smoking Worse Than Expected
The Value of Vitamin D continued...
Lieberman's study was a detailed analysis of how various dietary, lifestyle, and genetic factors influenced the development of these colon polyps, which often lead to colorectal cancers that kill some 55,000 Americans each year. None of the 3,100 veterans enrolled -- almost all men -- had any signs of colon polyps or cancer when the three-year study began, but being between ages 50 and 75, they were at a statistically higher risk of colon cancer.
They participated in the study at 13 VA centers across the U.S., but their levels of sun exposure were not measured. Most of the body's vitamin D comes from sunlight on bare skin, and getting about 10 minutes a day of sunscreen-free sun exposure when weather permits can absorb some 20,000 IUs of vitamin D, says Holick.
"This can be stored in fat layers," he says. But during winter months, he recommends taking a daily multivitamin, along with a separate 400 IU vitamin D supplement to lower risk of colon and other cancers.
Avoid Smoking, Red Meat
As expected, Lieberman's study also confirms previous research that being overweight, alcohol consumption, or frequently consuming fatty meats can boost risk. Men having beef, pork, or lamb more than four times a week were nearly three times as likely to develop polyps.
But the big surprise was in the risk caused by smoking. Being a current smoker doubled the risk of these polyps -- more than having a parent or sibling with colon cancer, which upped risk by 70%. Lieberman's theory: Smoking stimulates the overgrowth of cells in the lining of the colon, as it's been shown to do in other organs.
"In past studies, smoking was found to have a smaller or marginal effect, but we found it was profound -- never before was the risk higher than a high-degree relative with colon cancer," Lieberman tells WebMD. "This provides yet another reason to not smoke."