Following a diet loaded with ultra-processed foods (UPFs) – hot dogs, chicken nuggets, cereals etc – increases the risk for colorectal cancer, heart disease and death, according to results of two large observational studies published in The BMJ .
UPFs are highly manipulated and packed with added ingredients, including sugar, fat and salt, and are low in protein and fibre, reports Medscape. They include soft drinks, chips, chocolate, candy, ice cream, sweetened breakfast cereals, packaged soups, French fries, and many more.
Over the past 30 years, there’s been a steady increase in consumption of UPFs worldwide, coupled with mounting evidence that diets rich in UPFs raise the risk for several chronic diseases, including heart disease and cancer. Few studies, however, have focused specifically on the risk for colorectal cancer (CRC).
Novel data
To investigate, researchers analysed data on 206 248 American adults (46 341 men, 159 907 women) from the Nurses’ Health Study, Nurses’ Health Study II, and the Health Professionals’ Follow-up Study. Dietary intake was assessed every four years using detailed food frequency questionnaires.
During up to 28 years of follow-up, 1 294 men and 1 922 women developed CRC.
In Cox proportional models adjusted for confounding factors, men with the highest UPF intake had a 29% higher risk for CRC than men with the lowest UPF consumption. This association was limited to distal colon cancer, with a 72% increased risk.
Among subgroups of UPFs, a higher intake of meat/poultry/seafood-based, ready-to-eat products and sugary drinks was associated with increased risk for CRC among men.
“These products include some processed meats like sausages, bacon, ham and fish cakes. This is consistent with our hypothesis,” said lead author Lu Wang, PhD, with Tufts University in Boston, Massachusetts.
There was no association between overall UPF intake and risk for CRC in women and the reasons for this are unclear, the researchers say.
However, among the subgroups of UPFs, there was a positive association between ready-to-eat/heat mixed dishes and CRC risk, and an inverse association between yoghurt and dairy desserts and CRC risk among women.
It’s possible that foods like yoghurt help counteract the harmful impacts of other types of UPFs in women, the researchers say.
“Further research will be needed to determine whether there is a true sex difference in the associations, or if null findings in women in this study were merely due to chance or some uncontrolled confounding factors in women that mitigated the association,” said co-senior author Dr Mingyang Song, with Harvard TH Chan School of Public Health, Boston.
Hard on the heart, too
The related study in The BMJ shows a joint association between a low-quality diet and high intake of UPFs and increased risk for death from heart disease or any cause.
Study 1 details
Association of ultra-processed food consumption with colorectal cancer risk among men and women: results from three prospective US cohort studies
Lu Wang, Mengxi Du, Kai Wang, Neha Khandpur, Sinara Laurini Rossato, Jean-Philippe Drouin-Chartier, Euridice Martínez Steele, Edward Giovannucci, Mingyang Song, Fang Fang Zhang.
Published in The BMJ on 31 August 2022
Abstract
Objective
To examine the association between consumption of ultra-processed foods and risk of colorectal cancer among men and women from three large prospective cohorts.
Design
Prospective cohort study with dietary intake assessed every four years using food frequency questionnaires.
Setting
Three large US cohorts.
Participants
Men (n= 46 341) from the Health Professionals Follow-up Study (1986-2014) and women (n=159 907) from the Nurses’ Health Study (1986-2014; n=67 425) and the Nurses’ Health Study II (1991-2015; n=92 482) with valid dietary intake measurement and no cancer diagnosis at baseline.
Main outcome measure
Association between ultra-processed food consumption and risk of colorectal cancer, estimated using time varying Cox proportional hazards regression models adjusted for potential confounding factors.
Results
A total of 3,216 cases of colorectal cancer (men, n=1,294; women, n=1,922) were documented during the 24-28 years of follow-up. Compared with those in the lowest fifth of ultra-processed food consumption, men in the highest fifth of consumption had a 29% higher risk of developing colorectal cancer (hazard ratio for highest versus lowest fifth 1.29, 95% confidence interval 1.08 to 1.53; P for trend=0.01), and the positive association was limited to distal colon cancer (72% increased risk; hazard ratio 1.72, 1.24 to 2.37; P for trend<0.001). These associations remained significant after further adjustment for body mass index or indicators of nutritional quality of the diet (that is, western dietary pattern or dietary quality score). No association was observed between overall ultra-processed food consumption and risk of colorectal cancer among women. Among subgroups of ultra-processed foods, higher consumption of meat/poultry/seafood based ready-to-eat products (hazard ratio for highest versus lowest fifth 1.44, 1.20 to 1.73; P for trend<0.001) and sugar sweetened beverages (1.21, 1.01 to 1.44; P for trend=0.013) among men and ready-to-eat/heat mixed dishes among women (1.17, 1.01 to 1.36; P for trend=0.02) was associated with increased risk of colorectal cancer; yogurt and dairy based desserts were negatively associated with the risk of colorectal cancer among women (hazard ratio 0.83, 0.71 to 0.97; P for trend=0.002).
Conclusions
In the three large prospective cohorts, high consumption of total ultra-processed foods in men and certain subgroups of ultra-processed foods in men and women was associated with an increased risk of colorectal cancer. Further studies are needed to better understand the potential attributes of ultra-processed foods that contribute to colorectal carcinogenesis.
Study 2 details
Joint association of food nutritional profile by Nutri-Score front-of-pack label and ultra-processed food intake with mortality: Moli-sani prospective cohort study
Marialaura Bonaccio, Augusto Di Castelnuovo, Emilia Ruggiero, Simona Costanzo, Giuseppe Grosso, Amalia De Curtis, Chiara Cerletti, Maria Benedetta Donati, Giovanni de Gaetano, Licia Iacoviello.
Published in The BMJ on 31 August 2022
Abstract
Objective
To jointly analyse two food dimensions, the Food Standards Agency Nutrient Profiling System (FSAm-NPS), used to derive the Nutri-Score front-of-pack label, and the NOVA classification in relation to mortality.
Setting
Moli-sani Study, Italy 2005-10.
Participants
22,895 participants (mean age 55 (SD 12) years; 48% men).
Main outcomes measures
Associations between dietary exposures and mortality risk, assessed using multivariable cause specific Cox proportional hazard models controlled for known risk factors.
Results
A total of 2205 deaths occurred during 272,960 person years of follow-up. In the highest quarter of the FSAm-NPS index compared with the lowest quarter, multivariable adjusted hazard ratios for all cause and cardiovascular mortality were 1.19 (95% confidence interval 1.04 to 1.35; absolute risk difference 4.3%, 95% confidence interval 1.4% to 7.2%) and 1.32 (1.06 to 1.64; 2.6%, 0.3% to 4.9%), respectively. The hazard ratios were 1.19 (1.05 to 1.36; absolute risk difference 9.7%, 5.0% to 14.3%) and 1.27 (1.02 to 1.58; 5.0%, 1.2% to 8.8%), respectively, for all cause and cardiovascular mortality when the two extreme categories of ultra-processed food intake were compared. When these two indices were analysed jointly, the magnitude of the association of the FSAm-NPS dietary index with all cause and cardiovascular mortality was attenuated by 22.3% and 15.4%, respectively, whereas mortality risks associated with high ultra-processed food intake were not altered.
Conclusions
Adults with the lowest quality diet, as measured using the FSAm-NPS dietary index (underpinning the Nutri-Score), and the highest ultra-processed food consumption (NOVA classification) were at the highest risk for all cause and cardiovascular mortality. A significant proportion of the higher mortality risk associated with an elevated intake of nutrient poor foods was explained by a high degree of food processing. In contrast, the relation between a high ultra-processed food intake and mortality was not explained by the poor quality of these foods.
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