A 12-year study of over 100,000 adults reveals that your grocery shop may be increasing your risk of lung cancer, even if you’ve never smoked.
Study: Association between ultra-processed food consumption and lung cancer risk: a population-based cohort study. Image credit: Arinau20/Shutterstock.com
While ultra-processed foods (UPFs) are widely thought of as unhealthy, their association with lung cancer has not been validated so far. A recent study published in Thorax examined whether lung cancer risk was increased in people who ate more UPF. This study looked at overall lung cancer rates and two cancer types, non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC).
Introduction
UPFs are becoming increasingly widely adopted as a major part of the diet globally. This trend shows no signs of decreasing, even though UPF intake correlates with increased risks of death, cancer, irritable bowel disease, metabolic syndrome, obesity, and hypertension.
Lung cancer is a leading cause of death, with 2.2 million new cases being reported each year, and 1.8 million deaths worldwide. It remains latent for years or decades before manifesting itself clinically. These aspects lend urgency to early diagnostic and preventive efforts.
Cigarette smoking is a primary risk factor for lung cancer, but diet also plays an important role. UPFs are easily accessible, extremely delicious with addictive tastes, and very convenient as they avoid the mess and time involved in cooking. They also cost less than whole foods and have a long shelf life.
Conversely, they are non-nutritious and calorie-dense. UPF is made from food ingredients extracted or synthesized chemically or by highly processed food components. It is deficient in micronutrients, including vitamins and minerals, but high in sugars and salts, and a host of additives not found in home-cooked foods.
Unfortunately, UPF is “designed to replace all other food groups with attractive packaging and intensive marketing,” according to the authors. This flies in the face of its known association with metabolic and cardiovascular disease, including hypertension, obesity, diabetes, cancer, and death. It may not be coincidental that these conditions have increased in prevalence along with the global rise in UPF intake, across socioeconomic strata and regional diversity.
Therefore, the current study explored how UPF consumption is related to lung cancer and its primary subtypes.
About the study
The participants were part of the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial. Based on the NOVA system, their dietary patterns were assessed using a questionnaire and classified as UPF or otherwise.
Study findings
The study found 1,706 cases of lung cancer. Of these, 1,473 were NSCLC cases, making up the vast majority (86%), with 233 SCLC cases. The mean follow-up lasted 12 years among over 101,000 adults, with an average age of 63 at the start.
UPF intake mainly consisted of lunch meat (11%) and soft drinks (13.9%), caffeinated or otherwise.
After adjusting for multiple factors that could also increase lung cancer risk, the researchers concluded that people with the highest UPF intake also had a 41% higher risk of lung cancer, compared to those who ate the least UPF. The risk of NSCLC and SCLC was comparably raised, by 37% and 44%, respectively.
Even after adjusting for total energy intake, UPF intake was still associated with lung cancer risks and NSCLC risks. Interestingly, there was no linear dose-response pattern for SCLC, though the risk increased in a non-linear pattern with either lung cancer or NSCLC.
Prior research suggests that cutting out UPF in favor of minimally processed foods could decrease the risks of neck, colon, and liver cancers. The Western diet is linked to higher lung cancer rates. The current study is, however, among the first to demonstrate a link between UPF intake and lung cancer, both overall and its subtypes.
This association with lung cancer may be driven in part by UPF's poor nutritional profile, coupled with its replacement of healthy foods that reduce the risk. UPF may also inhibit satiety responses and interfere with how the body safely disposes of high-carbohydrate foods, resulting in excessive energy intake.
Irrespective of this, however, UPF intake was still associated with increased lung cancer risk, perhaps because it also predicts a deficiency of bioactive compounds.
The additives in UPF are still under study, but could potentially play a role in carcinogenesis. For instance, carrageenan is commonly used to thicken foods, but preclinical studies indicate that it inflames the gut and may indirectly promote lung cancer, as could disruption of glutamate metabolism.
Contamination of UPF with plastics-related polychlorinated biphenyls could be another possibility, as these have estrogenic activity and might promote lung cancer cell proliferation. According to prior population studies, these chemicals persist in the body despite regulatory bans.
The amount of industrial processing needed to produce UPF alters the structure and chemistry of the food substrate, with adverse effects on the bioavailability and potential generation of toxic substances. For instance, acrolein, found in grilled sausages and cigarette smoke, has been shown in cell studies to promote cancerous changes in the lung via mitochondrial DNA damage.
Conclusions
The study concluded that “higher consumption of UPF is associated with an increased risk of lung cancer, NSCLC, and SCLC.” However, causality cannot be established due to the study's observational nature.
The study was mainly performed on non-Hispanic White participants, limiting its generalizability. Future studies should extend and validate these results in more diverse and larger samples. If further research confirms these associations, public health policies should aim to reduce UPF intake worldwide.
Download your PDF copy now!
Self-sampling kits in GP visits boost cervical cancer screening