A diet that includes a lot of highly processed foods loaded with sugar, fat, and salt may do more than raise the risk for overweight, obesity, type 2 diabetes, and heart disease, researchers warn.
Highly processed foods such as packaged baked goods, instant soups, reconstituted meats, frozen meals, and shelf-stable snacks also contain substances that may significantly increase overall risk for cancer and breast cancer, according to Mathilde Touvier, PhD, of the Sorbonne Paris Cité Epidemiology and Statistics Research Center in Paris, France, and colleagues.
The team reports results from a prospective study of more than 100,000 participants from the NutriNet-Santé cohort, published online February 14 in the BMJ.
They found that a 10% increase in the proportion of ultraprocessed foods in the diet was associated with an 11% increase in overall cancer risk [hazard ratio [HR], 1.12; P < .001). These foods included ultraprocessed fats and sauces (P = .002), as well as sugary products (P = .03) and drinks (P = .005).
“If confirmed in other populations and settings, these results suggest that the rapidly increasing consumption of ultra-processed foods may drive an increasing burden of cancer in the next decades,” the authors warn.
The rapidly increasing consumption of ultra-processed foods may drive an increasing burden of cancer in the next decades.
They also note that many people worldwide are eating highly processed foods. Previous surveys that assessed individual food intake in Europe, the United States, Canada, New Zealand, and Brazil indicate that up to 50% of the total daily energy intake of people living in developed countries comes from highly processed foods and food products.
Increased Risk for Breast Cancer
The study also found that consumption of ultraprocessed foods was associated with a 12% increase in the risk for breast cancer (HR, 1.11; P = .02). Such products include those that contain a lot of sugar (P = .006)group.
No significant association was found between consumption of highly processed foods and an increased risk for prostate or colorectal cancer.
There was also no significant association between less processed foods and risk for cancer. These included canned vegetables, cheeses, and fresh, unpackaged bread.
Conversely, a diet consisting mostly of fresh or minimally processed foods, including fruits, vegetables, pulses, rice, pasta, eggs, meat, fish, and milk, was associated with a reduced risk for overall cancer and breast cancer, the study showed.
“These results remained statistically significant after adjustment for several markers of the nutritional quality of the diet (lipid, sodium, and carbohydrate intakes and/or a Western pattern derived by principal component analysis),” the study authors write.
Results Should Be Interpreted With Care
Because this is an observational study, no firm conclusions can be drawn about causality, Touvier told Medscape Medical News. “We need not be too alarmist. Caution is needed at this stage. These results need to be confirmed by other prospective cohorts, and deeper investigation [is needed] of the mechanisms involved.”
In an accompanying editorial, Adriana Monge and Martin Lajous, MD, of the National Institute of Public Health in Mexico City and the Harvard T. H. Chan School of Public Health, in Boston, Massachusetts, called the results “interesting” but warned that they must be interpreted with care.
A lot more work is needed to provide the epidemiologic evidence that could shape public policy or lead to the development of actionable advice, the editorialists say.
“We are a long way from understanding the full implications of food processing for health and wellbeing,” Monge and Lajous write. “The changing realities of the global food supply and the inherent limitations of epidemiologic studies call for more basic science, including data from animals, to inform further research on the effect of food processing on humans. Care should be taken to transmit the strengths and limitations of this latest analysis to the general public and to increase the public’s understanding of the complexity associated with nutritional research in free living populations.”
Empty Calories, Poor Nutrition
Processed foods are often characterized as offering empty calories and poor nutrition and having few vitamins and little or no fiber, Touvier and colleagues point out. Highly processed foods may contain additives and preservatives that enhance flavor and extend shelf life.
Experimental studies suggest that compounds formed during the production, processing, and storage of processed food may have carcinogenic properties. For instance, contaminants such as acrylamide can be produced during heat processing in processed fried potatoes, biscuits, bread, or coffee, the study authors say. “A recent meta-analysis found a modest association between dietary acrylamide and risk of both kidney and endometrial cancer in non-smokers,” the write.
Acrylamide is considered “probably [a] human carcinogen by the International Agency for Research on Cancer and the National Toxicology Program, as previously reported by Medscape Medical News.
Study Details
For their study, the team used data from the ongoing Web-based NutriNetSanté cohort. Since May 2009, persons from the general population in France have been recruited in a study of the association between nutrition and health.
The study included 104,980 participants (mean age, 43 years) who were without cancer at baseline. The participants were enrolled from 2009 to 2017; 78% were female.
At the time of inclusion, participants completed five online questionnaires, including one on dietary intake. Every 6 months, 24-hour dietary records were randomly assigned to track participants’ consumption of 3300 different food items over a 2-week period. Foods were classified on the basis of “the nature, extent, and purpose of the industrial processing.”
Food items included mass-produced packaged breads and buns, sweet or savory packaged snacks, packaged confectionery and desserts, sodas, and sweetened drinks, meatballs, poultry and fish nuggets, and other reconstituted meat products using nonsalt preservatives such as nitrites. Instant noodles and soups, frozen or shelf-stable prepared meals, and food products containing mostly sugar, oils, and fats or hydrogenated oils, modified starches, and protein isolates were also included.
Ultraprocessed foods such as dehydrated soups, processed meats, biscuits, and sauces have a high salt content, the researchers note. Foods preserved with salt are associated with an increased risk for gastric cancer, they add.
Better understanding of the effects of food processing could lead to policies targeting product reformulation, taxation, and marketing restrictions on ultraprocessed products, the researchers suggest. Brazil and France have recommended limiting the amount of ultraprocessed food in the diet in favor of raw and minimally processed foods, the authors note.
More epidemiologic and experimental research is needed to better understand the relative effect of nutritional composition, food additives, contact materials, and other contaminants, said Touvier. Next steps for her Nutritional Epidemiology Research team include analysis of detailed nutritional information on commercial food names and brands from the NutriNet-Santé cohort data. They will focus on the impact of long-term exposure to food additives, specific substances, and exposure to multiple additives.
“Most authorized additives are probably safe, but several additives have raised some concern in animal models and deserve investigation in observational studies in humans,” Touvier explained. “It’s about the cocktail effect of all these additives consumed together.”
The study was funded by the Minist ère de la Sant é , the Institut de Veille Sanitaire, the Institut National de la Pr é vention et de l’Education pour la Sant é, Ré gion Ile-de-France, the Institut National de la Sant é et de la Recherche M é dicale, the Institut National de la Recherche Agronomique, the Conservatoire National des Arts et Métiers, and the Université Paris. Dr Touvier and coauthors have disclosed no relevant financial relationships. Dr LaJous has a financial relationship with AstraZeneca.
BMJ. Published on February 14, 2018. Full text, Editorial
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