Doctor explains remarkable way eating fruits and vegetables can increase cancer risk
Eating plenty of fruits and vegetables has long been the cornerstone of a nutritious diet, but new research suggests that they could be behind a rising incidence of certain cancers in health conscious younger people.
Doctors and nutritionists advise that consuming lots of these healthy foods can lower the risk of a number of diseases, including cancer, but a spike in non-smokers under the age of 50 developing lung cancer has caused scientists to look for an underlying cause.
A recent study found that residue from the harmful pesticides that have been used for decades to boost agricultural crop yields could be playing a role in this concerning trend of younger people developing deadly cancers.
Lead investigator in the study, Jorge Nieva, a lung cancer specialist at the University of Southern California (USC), said: “Our research shows that younger non-smokers who eat a higher quantity of healthy foods than the general population are more likely to develop lung cancer."
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Nieva said that his findings showed that action needed to be taken to identify the underlying cause. He told the Mirror: “These counter-intuitive findings raise important questions about an unknown environmental risk factor for lung cancer related to otherwise beneficial food that needs to be addressed.”
While this USC research is concerning for people trying to follow a healthy diet, the lead investigator pointed out that it was possible to avoid what they suspected was behind this rising cancer incidence - foods grown using pesticides.
Following an organic diet is a simple way to avoid fruits and vegetable that been treated with chemicals to drive off or kill pests. Perversely, this includes eating meat, dairy, and even processed foods as they are unlikely to have interacted with pesticides.
Supporting this theory about the chemicals commonly used in agriculture, Dr Nieva pointed out that farm workers who work with pesticides have a recorded higher risk of developing lung cancer.
In order to test this theory that fruits and vegetables could be behind the rise in lung cancer in under 50s, the only demographic to see an increase in cases of this disease, researchers established the Epidemiology of Young Lung Cancer Project.
They surveyed 187 people who received a lung cancer diagnosis before the age of 50, asking them questions about their diet, background, as well as any history of smoking.
Many of them had never smoked, but had still developed lung cancer, albeit, a different form of the disease than the type found in tobacco users. When they analyzed their diets using a 1-100 Healthy Eating Index (HEI), they spotted something important.
Patients who had developed this type of non-smokers lung cancer actually had a noticeably higher HEI score than the general population, ranking an average of 67/100 instead of the typical 57.
These young people with lung cancer largely recorded a higher daily consumption healthy foods, like dark green vegetables and legumes, also registering a higher consumption of grains than the wider populace.
While the scientists behind the study could not test each patient's food for pesticide levels, they were able to roughly estimate their exposure to pesticides from published data on each foodstuff's incidence of pesticides.
This survey hopes to provide the springboard for further studies into the levels of pesticides found in the blood and urine of people with cancer, as well as which specific pesticides could be behind the trend.
Dr Nieva said: “This work represents a critical step toward identifying modifiable environmental factors that may contribute to lung cancer in young adults. Our hope is that these insights can guide both public health recommendations and future investigation into lung cancer prevention.”
But while this research is set to be presented to the annual meeting of the American Association for Cancer Research, not every in the field of oncology agrees with its findings.
Professor Stephen Duffy, Emeritus Professor of Cancer Screening, Queen Mary University of London (QMUL), said: “It is not clear from the abstract exactly when the food frequency questionnaires were administered, but it does appear that this was after diagnosis with lung cancer.
"Is it possible that there is an element of reverse causality here? That is, people with a diagnosis of a serious illness may make lifestyle changes in response, for example to a more healthy diet. Also, it appears that the comparison is with standards from an external study."
He added: "Thus these results may be subject to confounding with factors related to the time of recruitment and other factors which differ between the two studies. I would certainly not advise against a healthy diet on the basis of these results.”
Interestingly, the study's findings could also prove the scientific maxim that causation does not equate to causation, as healthier people have other risk factors that could be behind the trend.
Prof Peter Shields, Emeritus Professor of Medical Oncology at Ohio State University, said: "It is well known that leanness is a risk factor for lung cancer, opposite to most other cancers. The authors may not be seeing anything more than this.
"More importantly, the grouping of those mutations together is arbitrary and unclear if they share the same carcinogenic pathways, versus those are the only ones we know how to treat. And, even more important, a role for pesticides is entirely speculative.
“This research should be considered exploratory, as it is in early stage, and is a small study."
William Morgan