Veronica Hackethal, MD
February 11, 2019
People who consume higher levels of ultraprocessed foods may be at increased risk for death, according to a study published online February 11 in JAMA Internal Medicine.
"Findings from this prospective study of a large French cohort suggest for the first time, to our knowledge, that an increased proportion of ultraprocessed foods in the diet is associated with a higher risk of overall mortality," write Laura Schnabel, MD, from the Sorbonne Paris Cite, Bobigny, France, and colleagues.
Ultraprocessed foods include mass-produced, ready-to-eat foods such as packaged snacks, sugary drinks, breads, candies, ready-made meals, and processed meats. Such foods usually contain "empty calories" and have a high caloric content with little nutritional value. They are low in fiber and high in carbohydrates, saturated fats, and salt. Usually, they contain food additives and contaminants that may be harmful to health, including some that may be carcinogenic, according to the authors.
People often select ultraprocessed foods because of their affordability, ease of preparation, and resistance to spoilage. Such foods are also highly marketed and are often prominently displayed in supermarkets.
Yet such convenience may come at a cost. Accumulating evidence has linked ultraprocessed foods to increased risk for chronic diseases, including dyslipidemia, obesity, hypertension, and cancer. Whether this leads to an increased risk for death has never been investigated before.
Therefore, the researchers conducted an observational prospective cohort study. They analyzed data from 44,551 adults aged 45 years and older who were participants in the French NutriNet-Santé Study, an ongoing, nationwide, Web-based nutritional study that was launched in May 2009. The researchers conducted a follow-up through December 15, 2017. Of the participants, 73.1% were women, and the mean age was 57 years.
The researchers collected information on food intake using a series of three Web-based 24-hour dietary recall questionnaires, which were completed every 6 months. Questionnaires asked about foods typically consumed by the respondents at breakfast, lunch, and dinner, as well as snacks. The questionnaire also provided validated photos so that participants could self-report portion size.
Respondents reported that, on average, 14.4% of the total weight of the food they consumed came from ultraprocessed foods. In other words, ultraprocessed foods accounted for 29.1% of their total daily caloric intake.
During the course of the 7-year study, 602 participants died (1.4% of the study group).
For every 10% increase in the proportion of ultraprocessed foods in the diet, the risk for all-cause death increased by 14% (hazard ratio per 10% increment, 1.14; 95% confidence interval, 1.04 – 1.27; P = .008).
Notably, these analyses adjusted for many potential confounders that could have affected results, including sex, age, monthly income, educational level, marital status, residence (urban, rural), physical activity level, smoking status, alcohol intake, energy intake, and first-degree family history of cancer/cardiovascular disease.
The authors emphasize that adjusting for an overall healthy diet (as estimated by adherence to French national recommendations) weakened the association between ultraprocessed foods and death but did not remove it. That suggests that an overall healthy diet may play a role in the association, but other factors may also be involved.
They went on to explain that additives, as well as the high salt, high sugar, and low fiber content of ultraprocessed foods, could contribute to increased risk for chronic diseases. Those, in turn, could ultimately lead to the increased risk for mortality found in this study.
"Further studies are needed to confirm those results in different populations and to disentangle the various mechanisms by which ultraprocessed foods may affect health, including both their nutritional features and their food processing–related characteristics," they write.
They mention several limitations to the study. Notably, participation in the study was voluntary and may have attracted participants who were more health conscious than the general population. If so, the results may underestimate the link between ultraprocessed foods and death. Also, follow-up may have been too short to capture some deaths resulting from chronic diseases, which develop over decades.
Nevertheless, the authors conclude: "Ultraprocessed foods consumption has largely increased during the past several decades and may drive a growing burden of noncommunicable disease deaths."
The authors have disclosed no relevant financial relationships.