Can Certain ‘Poor Carb’ Diets Raise Nonsmokers’ Lung Cancer Risk?

Even people who’ve never smoked can get lung cancer, and a new study suggests their risk for the disease may rise if they eat a diet rich in certain carbohydrates.

These so-called “high glycemic index” diets – regimens that trigger higher levels of insulin in the blood – tend to be heavy in refined, “poor quality” carbs, one expert explained.

“The glycemic index and glycemic load are methods to estimate the quality and quantity of dietary carbohydrates,” said Dr. Rishi Jain, a medical oncologist at Fox Chase Cancer Center in Philadelphia. “Examples of foods with a high glycemic index include white bread and white potatoes.”

Jain explained that as rates of obesity and heart risk factors rise in the United States, so does the number of Americans with “insulin resistance,” a precursor to diabetes. And he said insulin-linked disorders, which are often tied to high-glycemic diets, “have been implicated as potential contributors to a variety of chronic conditions, including certain cancers.”

Could lung cancer be one of those malignancies? Dr. Xifeng Wu, chair of cancer prevention at the University of Texas MD Anderson Cancer Center in Houston, conducted the new study to help answer that question.

Overall, people who registered in the top fifth in terms of a high-glycemic diet had a 49% greater risk of developing lung cancer versus those in the bottom fifth, Wu’s team reported.

But the trend was even stronger when the study focused on people who had never smoked. In that group, those who scored highest in terms of a high-glycemic diet had more than double the odds of lung cancer compared to never-smokers who had the lowest glycemic index scores.

Wu and her colleagues reported their finding March 4 in the journal Cancer Epidemiology, Biomarkers & Prevention.



According to Wu, focusing on never-smokers is important because it eliminates smoking as a confounding risk factor – giving a clearer picture of the potential role of diet in lung cancer risk.

Co-author Stephanie Melkonian noted that high-glycemic diets are linked to insulin resistance, which in turn may encourage the activity of certain cellular “growth factor” chemicals that are known to play a role in cancer.

Overall, “this study contributes to the growing evidence that poor dietary habits and obesity play a critical role in cancer development,” Jain said.

My Take:
Smoking is a well-established risk factor in lung cancer. If you calculate the number of cigarettes a person has smoked in their lifetime, you can calculate their odds of developing lung cancer. For women, about 250,000 cigarettes is a virtual guarantee of lung cancer. For men, it’s a little higher at 325,000.

This study shows a similar, less well defined risk with the consumption of processed grains and sugars. Breads, cereals, pasta, and sweets are all high glycemic foods. The more of these you eat, the greater the risk of lung cancer.

The Bottom Line:
If people understood the risks associated with refined, processed foods as well as they do the risks associated with smoking, we wouldn’t have epidemic levels of obesity and diabetes in this country. Please read my ongoing series on diet each Wednesday on my blog and make some positive changes in your diet.

Source: March 4, 2016 National Institutes of Health