In the present study published in the Clinical Nutrition journal, researchers performed a meta-analysis to evaluate the relationship between ultra-processed food (UPF) consumption and cancer.
Study: Ultra-processed food consumption and cancer risk: a systematic review and meta-analysis. Image Credit: meigav/Shutterstock.com
Cancer, a leading cause of mortality globally, has been associated with changes in lifestyle-associated factors, including alcohol intake, smoking habits, diet, and physical activity.
UPF foods are dietary formulations that have undergone multiple levels of processing in industries to lower microbial deterioration, increase shelf-life, enhance transportability over long distances, and enhance palatability.
UPFs comprise various diet additives, including colorants, sweeteners, and emulsifiers, and are staple foods in several nations. Studies have reported that Western diet consumption with high UPF content increases the chances of developing non-communicable diseases, including cancer.
However, data on the molecular mechanisms, carcinogenic properties, and characteristics of the effects of increased UPF intake on health are limited.
About the study
In the present study, researchers investigated whether UPF consumption elevated cancer risk. Databases such as EMBASE and PubMed were searched on 28 March 2022 and 5 January 2023 for original research articles, including peer-reviewed and observational-type studies.
They assessed the relationship between UPF consumption and cancer risk among adults. UPFs were identified based on the NOVA scheme as the study exposure and cancer as the study’s outcome.
Random-effects-type meta-analysis was performed. Records were reviewed, and the risk of bias was evaluated based on the National Institute of Health (NIH)’s tools for quality assessment.
The study outcomes included cancer (breast, colorectal, pancreatic, prostate), central nervous system tumors, and chronic lymphocytic leukemia.
Hazard ratios (HR) for prospective cohort-type studies and odds ratios (OR) for case-control-type studies were calculated.
Records assessed for melanoma and skin cancers of non-melanoma-type using or not using multiple NOVA classifications were excluded from the analysis. In addition, meta-analyses, reviews, editorials, letters, and animal studies were excluded.
In the initial search, 265 records were identified, from which 23 studies were published before 2009, and 65 were duplicates. After the exclusion, the remaining 177 studies underwent screening.
164 of which, with unmet eligibility criteria, were excluded. As a result, 11 relevant records, including three prospective cohort-type studies and eight studies of the retrospective case-control-type, were considered for the final analysis.
Of 11 records, four assessed the association between UPF and colorectal cancer; one study evaluated the risk of pancreatic cancer; one determined the link between UPF intake and central nervous system tumors; another studied chronic lymphocytic leukemia incidence; one studied premenopausal breast cancer patients, and one studied the overall risk of that of breast cancer.
The sample population varied across studies, ranging between 132 and 206,248 individuals, including participants of the French NutriNet-Santé study, the Nurses’ Health Study (NHS), NHS II, the Health Professionals Follow-up Study (HPFS), and the Mediterranean diet in relation to cancer of brain (MEDICEA) study.
Nine records documented a significant positive relationship between ultra-processed food intake for all cancers investigated, except prostate cancer, after adjusting data for confounding variables, including adiposity and total caloric intake.
A 10.0% increase in the dietary UPF proportion was related to elevated breast cancer risks, with HR values of 1.1 and breast cancer, respectively. Additionally, increased UPF consumption was related to an elevated risk of pancreatic tumors (HRQ4 versus Q1, 1.5) and colorectal tumors (ORT3 versus T1, 1.3).
The relationships between UPF intake and the risk of developing chronic lymphocytic leukemia and central nervous system tumors were modest.
In the meta-analysis, pooling the findings for cancer outcomes indicated that UPF consumption was significantly related to cancer for prospective cohort-type studies (HR 1.1) and those of case-control type (OR 1.2).
Diet records were largely obtained using food frequency questionnaires, online 24-hour diet recalls, and diet history questionnaires (DHQ). UPF items contributing to the association include sugary foods and beverages, ready-to-eat foods, bread, cakes, cookies, desserts, dairy products, and cereals.
The association between UPF intake and cancer development was stronger for individuals below 65 years (HR 2.2) than for those aged 65 years and above (HR 1.3).
Overall, the study findings showed a consistently significant relationship between UPF intake and the risks of various cancers, including pancreatic, colorectal, and breast cancer.
The findings could inform dietary policy-making and strategy development to replace or reduce ultra-processed foods with less processed dietary alternatives, thereby reducing UPF demand and enhancing population health.
However, further research is required to assess the potential carcinogenic properties of particular UPF components in humans.