London - White bread, cornflakes, potatoes and popcorn are among foods that increase the chance of developing lung cancer, doctors have warned.
The largest study of its kind found people who ate such foods were up to 2.25 times as likely to develop the disease as those who did not.
And despite lung cancer being associated with smoking, the effect was particularly clear among non-smokers.
The US research centres on how carbohydrate-rich foods are digested. White bread, potatoes, cornflakes and other foods with a high glycaemic index (GI) are broken down quickly, causing rapid rises and falls in blood sugar levels that can fuel hunger and weight gain.
Now, they have been linked to lung cancer, which kills more people than any other form of the disease – with more than 35 000 deaths a year in the UK.
The University of Texas researchers quizzed almost 3 500 men and women, including many lung cancer patients, about their diet and lifestyle.
Comparing the habits of the cancer patients with the healthy individuals flagged up a clear link with high-GI foods.
Those who ate the most such foods increased their chance of developing the disease by 49 percent compared with those who consumed the least. But the risk of one type of lung cancer was almost doubled.
Researcher Dr Stephanie Melkonian said it is likely that the high blood sugar levels caused by high-GI foods trigger changes in hormones called insulin-like growth factors (IGFs), which are thought to fuel tumours.
White bread and other high-GI products were found to be particularly risky for non-smokers.
Those whose diets contained the most high-GI foods were 2.25 times as likely to develop lung cancer as other non-smokers, the journal Cancer, Epidemiology, Biomarkers & Prevention reports. It is thought that cigarettes increase the likelihood of lung cancer so much that the damage done by eating habits is masked to some extent among smokers.
The study’s senior author, Xifeng Wu, a professor of cancer prevention, said the link with diet helps explain why some non-smokers develop lung cancer.
She added: “The results from this study suggest that, besides maintaining healthy lifestyles, reducing the consumption of foods and beverages with high glycaemic index may serve as a means to lower the risk of lung cancer.”
Low-GI foods include most fruit, beans, vegetables, unprocessed grains and wholemeal bread. However, not all healthy foods have a low GI. For instance, chocolate cake has a lower GI than watermelon and parsnips.
Casey Dunlop, of Cancer Research UK, said: “It’s important to remember that more than eight in ten cases of lung cancer are caused by smoking, and more research will be needed to figure out the effect of glycaemic index on cancer risk. If you smoke, giving up is the best gift you can give yourself, your friends and your family.”
The average British man has a one in 13 chance of developing lung cancer. For women, the odds are slightly lower at one in 17.
Daily Mail