Ultraprocessed Foods and Cancer: Small Changes May Lower Risk

Sharon Worcester

March 24, 2023

Processed and ultraprocessed food consumption has been shown to increase the risk for various cancers. A new analysis suggests that replacing even a small amount of such foods with an equal amount of minimally processed options may reduce that risk.

Using data from more than 450,000 participants, the dietary substitution analysis found that swapping out just 10% of processed foods with minimally processed foods significantly lowered the risk for cancer overall by 4% as well as the risk for several cancer types, including esophageal squamous cell carcinoma by 43% and hepatocellular carcinoma by 23%.

Making this substitution with ultraprocessed foods also appeared to lower cancer risk but often to a lesser degree. For instance, swapping 10% of ultraprocessed foods for minimally processed foods lowered the overall cancer risk by just 1%, the risk of hepatocellular carcinoma by 27%, and the risk of esophageal squamous cell carcinoma by 20%.

Overall, "this study suggests that the replacement of processed and ultra-processed foods and drinks with an equal amount of minimally processed foods might reduce the risk of various cancer types," Nathalie Kliemann, PhD, from the WHO's International Agency for Research on Cancer, Lyon, France, and colleagues concluded.

The findings were published in the March issue of The Lancet Planetary Health.

Processed and ultraprocessed foods tend to have high-energy density and low nutritional value, and some epidemiological evidence indicates a possible link between consuming ultra-processed food and cancer outcomes.

Kliemann and colleagues, for instance, recently published a study showing a link between ultraprocessed food consumption and increased risk for cancer, particularly ovarian cancer, as well as increased risk of dying from cancer. That study of nearly 200,000 middle-aged adults in the UK Biobank database showed that for each 10 percentage point increase in the consumption of ultraprocessed foods, there was a 2% increase in the overall incidence of cancer and a 19% increase in ovarian cancer incidence.

However, conflicting reports exist, and research exploring associations between processed foods and cancer remains limited.

The researchers wanted to better understand the potential association between the degree of food processing and risk for cancer in a larger cohort of individuals.  

The investigators performed a dietary substitution analysis using data from more than 450,000 participants from the European Prospective Investigation into Cancer and Nutrition (EPIC) study and looking at 25 anatomical sites. EPIC study participants, who had no cancer diagnoses prior to enrollment, were identified between March 1991, and July 2001. Of the 450,111 included in the analysis, 47,573 were diagnosed with cancer during a mean follow-up of 14.1 years. Mean age at recruitment was 51 years, and mean BMI was 25.3 kg/m2.

Food items were classified according to their level of processing using the NOVA classification system: minimally or nonprocessed foods (NOVA 1), processed culinary ingredients (NOVA 2), processed foods (NOVA 3), and ultraprocessed foods (NOVA 4). The investigators highlighted comparisons between NOVA 1 and NOVA 3 and between NOVA 1 and NOVA 4.

The analysis revealed that swapping out just 10% of processed foods with minimally processed foods significantly lowered the risk for cancer overall (HR, 0.96) as well as for esophageal squamous cell carcinoma (HR, 0.57), hepatocellular carcinoma (HR, 0.77), head and neck cancers (HR, 0.80), colon cancer (HR, 0,88), rectal cancer (HR, 0.90), and postmenopausal breast cancer (HR, 0.93)

Swapping 10% of ultraprocessed foods for minimally processed foods lowered the risk of cancer overall only slightly (HR, 0.99) as well as the risk for various cancer types, including hepatocellular carcinoma (HR, 0.73), head and neck cancers (HR, 0.80), esophageal adenocarcinoma (HR, 0.80), and colon cancer (HR, 0.93).

The authors noted several limitations to the analysis, perhaps most notably that intake of ultraprocessed foods contributed to about 32% of total daily energy intake among study participants, but today that percentage could be nearly double across European countries.

"This discrepancy might explain the fewer significant associations observed between ultraprocessed foods and cancer risk than in processed foods and cancer risk," the authors suggest.

The findings are "broadly in line with current evidence," but the authors also noted some inconsistencies. For example, the current study showed a positive association between processed food consumption and risk for colorectal cancer and postmenopausal breast cancer, whereas other studies have not.

Overall, though, the authors concluded that increased consumption of minimally processed and fresh foods was associated with reduced overall risk for cancer and risk for specific cancers, and increased consumption of processed and ultraprocessed foods was associated with increased cancer risks.

This study "is the largest study investigating these associations between food processing and cancer risk and therefore has greater power to detect differences in populations, potentially explaining why we found overall more significant results for different cancer sites than other cohorts," Kliemann and colleagues write.

This study was funded by Cancer Research UK, the French National Cancer Institute, and World Cancer Research Fund International. The authors declared no competing interests. 

Lancet Planet Health. Published in the March 2023 issue. Full text

Sharon Worcester, MA, is an award-winning medical journalist based in Birmingham, Alabama, writing for Medscape, MDedge and other affiliate sites. She currently covers oncology, but she has also written on a variety of other medical specialties and healthcare topics. She can be reached at  sworcester@mdedge.com  or on Twitter:  @SW_MedReporter.

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