- As the proportion of ultra-processed foods (UPFs) in the Western diet increases, concerns are growing about their health effects.
- Studies have linked UPFs with many health conditions, including obesity, type 2 diabetes, cardiovascular disease, and several types of cancer.
- Now, a study suggests that high consumption of UPFs could increase a person’s chance of developing lung cancer.
- While observing a link, the study cannot prove that UPFs cause lung cancer, but highlights a need for further studies.
Ultra-processed foods (UPFs) — formulations of food substances often modified by chemical processes and then assembled into ready-to-consume hyper-palatable food and drink products using flavors, colors, emulsifiers, and many other cosmetic additives — are often in the news for their effect on our health.
These products, which include carbonated soft drinks, mass-produced bread, confectionery, ice creams, sweet and savory snacks, and ready meals, make up around 60% of the energy consumed in the United States.
A new study has now linked high UPF intake with an increased risk of developing lung cancer.
The research, published in Thorax, found that high consumption of UPFs was associated with a greater risk of both non-small cell (NSCLC) and small cell lung cancer (SCLC).
Nilesh Vora, MD, board-certified hematologist and medical oncologist and medical director of the MemorialCare Todd Cancer Institute at Long Beach Medical Center in Long Beach, CA, who was not involved in the study, found the link surprising:
“The study generates a compelling hypothesis that needs further research to validate the claim,” he told Medical News Today.
The researchers collected data from people enrolled in the
At enrolment, all participants completed a baseline questionnaire, which recorded demographics, medical history, and other risk factor information, and a diet history questionnaire, to assess the frequency and portion size of food consumption and nutrient intake during the previous year.
From the diet questionnaire and four 24-hour dietary recalls, the researchers assessed how much UPF people consumed, dividing them into 4 quartiles for UPF consumption.
The lowest quartile consumed around 0.5 servings of UPF per day, and the highest 6.0 servings, with a mean intake of 2.8 servings per day.
Researchers followed up the participants for a mean of 12.2 years, during which time there were 1,706 lung cancer diagnoses. Of these, 1,473 (86.3%) were NSCLC, and 233 (13.7%) SCLC.
Those who ate more UPF had a higher likelihood of being diagnosed with lung cancer. In the lowest UPF intake group, 331 out of 25,433 people (1.3%) were diagnosed with lung cancer, and in the highest UPF group, 485 out of 25,434 (1.9%) had a lung cancer diagnosis.
The researchers concluded that those who ate the most UPF had a 41% relatively higher hazard of lung cancer than those in the lowest quarter.
People in the highest quartile for UPF consumption also had lower intake of minimally processed foods like fruits, vegetables, and whole grains, which the American Institute for Cancer Research advises can lower a person’s risk of many cancers.
The researchers suggest several possible reasons why UPF might increase lung cancer risk, including:
- poor nutritional quality of UPF and lower nutrient availability due to industrial processing.
- some of the additives commonly used in UPFs, such as glutamate and carrageenan, could increase lung cancer risk, possibly by disrupting the lung and gut microbiota.
- harmful contaminants from processing and packaging that could be carcinogenic.
Katrina Brown, senior cancer intelligence manager at Cancer Research UK, who was not involved in the study, cautioned that firm conclusions could not be drawn from the research:
“What we’d want to see in the lung cancer space specifically, we’d want to see really, really close adjustment for smoking and for occupational exposures. Without that, in the lung cancer space, it’s impossible to draw firm conclusions from research. And also more accurate measurement of diet because if you’re looking at a diet study, you have to be measuring it really, really accurately. It’s very difficult to do that. It’s incredibly difficult to do that at scale.”
“There’s also the possibility, I think, of shared risk factors. If you have a diet high in UPFs, are you also more likely to smoke cigarettes? Are you also more likely to be in a job where you’re exposed to these other risk factors?” she added.
This was an observational study that relied on self-reported information about diet, so the findings cannot prove that UPFs cause lung cancer.
The authors highlight this and other limitations of their study, including a lack of data about smoking intensity for participants and the lack of ethnic diversity of the participants, most of whom were non-Hispanic white.
Brown highlighted some of these limitations:
“There is adjustment for smoking in the paper, but there’s nothing about how long a person smoked for, or how heavily they smoked. And we know that those are variables that are very closely associated with lung cancer incidence.”
“Also,” she added, “the lack of adjustment for occupational exposure is a concern. There are a number of substances that can increase lung cancer risks, typically encountered at volume in occupational settings. Asbestos, silica, lots of dusts and chemicals can have quite a high relative risk for lung cancer.”
Vora emphasized that to generate more significant data: “More research should be done in a prospective fashion with controlled variables.”
This latest study linking UPFs to lung cancer adds to the evidence of potential harms from UPFs.
“UPFs can be high in fat, salt and sugar, which are associated with overweight and obesity, and we know that overweight and obesity can increase cancer risk. Cutting down on these types of foods can be part of a healthy, balanced diet. When it comes to lung cancer, not smoking is the best thing people can do to reduce their cancer risk.”
— Katrina Brown, Cancer Research UK
While welcoming the study, Brown told MNT:
“I don’t think that we would say that this study sounds huge alarm bells. But we certainly wouldn’t disagree with the core recommendation to try and reduce the amount of processed food that you consume and replace it with healthier alternatives.”
“It’s interesting as it gets as further to knowing more about UPFs. It’s that body of evidence that we need to build up, but this single study doesn’t tip the balance,” she added.
