White bread, corn flakes intake may up lung cancer risk

Houston: Consumption of foods with a high glycemic index such as white bread, bagels, corn flakes and puffed rice may be associated with an increased risk of developing lung cancer, a new study has warned.

The study by scientists from the University of Texas in US is the largest to investigate potential links between glycemic index (GI) and lung cancer.

The findings also unveil for the first time that GI was more significantly associated with lung cancer risk in particular subgroups, such as never-smokers and those diagnosed with the squamous cell carcinoma (SCC) subtype of lung cancer, researchers said.

In US, lung cancer is the second most common cancer in both men and women, but is by far the leading cause of cancer mortality. Accumulating evidence suggests that dietary factors may modulate lung cancer risk, researchers said.

Diets high in fruits and vegetables may decrease risk, while increased consumption of red meat, saturated fats and dairy products have been shown to increase lung cancer risk, they said.

Glycemic index is a measure of the quality of dietary carbohydrates, defined by how quickly blood sugar levels are raised following a meal.

Examples of low GI foods include whole-wheat or pumpernickel bread, rolled or steel-cut oatmeal and pasta.

Previous studies have showed associations between GI and glycemic load (GL), a related measure of carbohydrate quantity, and risk of numerous other cancers.

"Diets high in glycemic index result in higher levels of blood glucose and insulin, which promote perturbations in the insulin-like growth factors (IGFs)," said Stephanie Melkonian from University of Texas.

To clarify the associations between GI, GL and lung cancer risk, researchers surveyed 1,905 patients newly diagnosed with lung cancer and 2,413 healthy individuals.

Participants self-reported past dietary habits and health histories. Dietary GI and GL was determined using published food GI values, and subjects were divided into five equal groups, based on their GI and GL values.

"We observed a 49 per cent increased risk of lung cancer among subjects with the highest daily GI compared to those with the lowest daily GI," said Xifeng Wu from University of Texas.

In never smokers, the researchers found that those in the highest GI group were more than twice as likely to develop lung cancer as those in the lowest group. Among smokers, the risk was only elevated by 31 per cent between the two groups.

The relatively mild effects of a risk factor such as GI are more evident in the absence of the dominant risk factor, researchers said.

They suggest limiting foods and beverages with high GI, such as white bread or bagels, corn flakes and puffed rice, for a more balanced diet and to lower the risk for lung cancer and chronic diseases.

The findings were published in the journal Cancer Epidemiology, Biomarkers and Prevention.