A study out this month made splashy media headlines announcing a link between carbohydrates and lung cancer.
A CNN headline breathlessly wondered if carbs are as bad as cigarettes when it comes to lung cancer.
The news certainly seemed worrisome. The study by MD Anderson Cancer Center researchers suggests an association between glycemic index (GI) – a measure of how much carb-containing foods increase blood glucose – and increased lung cancer risk. High-GI foods include white rice, white bread and potatoes.
The study of nearly 2,000 patients concluded that the risk of lung cancer in the 20 percent of patients with the highest GI diets was 49 percent greater than the 20 percent with the lowest GI diets.
Before you swear off mashed potatoes, the data have to be put in perspective, says Stephen Malkoski, MD, PhD, a pulmonary and critical-care specialist with University of Colorado Hospital.
For one thing, Malkoski says, the study only establishes an association between GI and lung cancer. “It doesn’t prove causality,” he says.
A 49 percent increase in risk might sound alarming, Malkoski added, but it means that the relative risk of lung cancer is about 1.5 times greater for the highest GI group than the lowest. As a risk factor, that’s about on par with a family history of lung cancer. By comparison, the risk of cancer increases about eight times for a half-pack-a-day lifetime smoker and 15 times for a pack-a-day puffer.
“The top risk factors for lung cancer, in order, are smoking, smoking, smoking, and smoking,” Malkoski says.
People who are at risk of diabetes have good reason to consider modifying the amount of high-GI carbs in their diets, Malkoski emphasizes.
When it comes to worrying about carbs, “Diabetes trumps lung cancer risk by a lot,” he says.