Abstract
Background: Both ultra-processed foods and animal-derived foods have been associated with mortality in some studies. Objectives: We aimed to examine the association of 2 dietary factors (ultra-processed foods and animal-based foods), adjusted for each other, with all-cause mortality. Methods: The setting is an observational prospective cohort study in North America, recruited from Seventh-day Adventist churches, comprised of 95,597 men and women, yielding an analytic sample of 77,437 participants after exclusions. The exposure of interest was diet measured by FFQ, in particular 2 dietary factors: 1) proportion of dietary energy from ultra-processed foods (other processing levels and specific substitutions in some models) and 2) proportion of dietary energy from animal-based foods (red meat, poultry, fish, and eggs/dairy separately in some models). The main outcome was all-cause mortality. Mortality data through 2015 were obtained from the National Death Index. Analyses used proportional hazards regression. Results: There were 9293 deaths. In mutually adjusted continuous linear models of both dietary factors (ultra-processed and animal- based foods), the HR for the 90th compared with the 10th percentile of the proportion of dietary energy from ultra-processed food was 1.14 (95% CI: 1.07, 1.21, comparing 47.7% with 12.1% dietary energy), whereas for animal-based food intake (meats, dairy, eggs) it was 1.01 (95% CI: 0.95, 1.07, comparing 25.0% with 0.4% dietary energy). There was no evidence of interaction (P = 0.36). Among animal-based foods, only red meat intake was associated with mortal- ity (HR: 1.14; 95% CI: 1.08, 1.22, comparing 6.2% with 0% dietary energy). Conclusions: Greater consumption of ultra-processed foods was associated with higher all-cause mortality in this health-conscious Adventist population with many vegetarians. The total of animal- based food consumption (meat, dairy, eggs) was not associated with mortality, but higher red meat intake was. These findings suggest that high consumption of ultra-processed foods may be an important indicator of mortality. Am J Clin Nutr 2022;115:1589-1601.
Generated Summary
This observational prospective cohort study investigated the association between ultra-processed food intake, animal-based food intake, and all-cause mortality in the Adventist Health Study-2 (AHS-2) cohort in North America. The study recruited 95,597 men and women from Seventh-day Adventist churches. Data was collected using a food frequency questionnaire (FFQ) to assess dietary intake. The main exposures of interest were the proportion of dietary energy from ultra-processed foods and animal-based foods, adjusted for each other. The primary outcome was all-cause mortality, with mortality data obtained from the National Death Index through 2015. Analyses utilized proportional hazards regression. The study aimed to examine the independent associations of these two dietary factors, with particular attention to the impact of ultra-processed foods in a population with varying vegetarian dietary patterns.
Key Findings & Statistics
- Mortality Rates: The study analyzed 9293 deaths within the cohort.
- Ultra-Processed Foods and Mortality: The hazard ratio (HR) for the 90th percentile compared to the 10th percentile of dietary energy from ultra-processed food was 1.14 (95% CI: 1.07, 1.21).
- Animal-Based Foods and Mortality: The HR for the 90th percentile compared to the 10th percentile of animal-based food intake (meats, dairy, eggs) was 1.01 (95% CI: 0.95, 1.07).
- Red Meat and Mortality: Red meat intake was associated with mortality (HR: 1.14; 95% CI: 1.08, 1.22), particularly among those who consume red meat.
- Dietary Energy from Ultra-Processed Foods by Quintiles:
- Quintile 1 (0%-17.0%): 1917 deaths (12.4%)
- Quintile 2 (17.1%-24.5%): 1961 deaths (12.8%)
- Quintile 3 (24.6%-31.5%): 1946 deaths (12.6%)
- Quintile 4 (31.6%-40.5%): 1765 deaths (11.4%)
- Quintile 5 (40.6%-95.8%): 1704 deaths (10.8%)
- Dietary Energy from Animal-Based Foods by Quintiles:
- Quintile 1 (0%-2.4%): 2058 deaths (13.3%)
- Quintile 2 (2.5%-7.3%): 1908 deaths (12.3%)
- Quintile 3 (7.4%-12.7%): 1813 deaths (11.7%)
- Quintile 4 (12.8%-19.4%): 1779 deaths (11.5%)
- Quintile 5 (19.5%-86.5%): 1735 deaths (11.2%)
- Impact of Substitutions (Figure 3): The study found a positive association for ultra-processed food intake similar to those reported in Figure 2. The study found a positive association for ultra-processed food similar in magnitude to those reported in Figure 2, and the association was again demonstrated, regardless of the particular substitution.
Other Important Findings
- The study found that a greater consumption of ultra-processed foods was associated with higher all-cause mortality in this health-conscious Adventist population, with many vegetarians.
- The total consumption of animal-based foods (meat, dairy, eggs) was not associated with mortality, but higher red meat intake was.
- Among animal-based foods, only red meat intake was associated with mortality.
- Greater consumption of ultra-processed foods was associated with higher all-cause mortality, irrespective of animal-based food intake.
- The study found that ultra-processed food intake was significantly associated with higher mortality (HR: 1.14; 95% CI: 1.08, 1.21) in a continuous linear model.
- The total animal-based food intake was not clearly associated with all-cause mortality.
- There was no evidence of interaction between ultra-processed and animal-based foods.
- Comparing 35% calories from ultra-processed food with 2.5% of calories, the HR for ultra-processed was 1.14 (95% CI: 1.07, 1.20) and for animal-based was 1.02 (95% CI: 0.94, 1.10).
- Ultra-processed foods was weakly associated with CVD mortality (HR: 1.09; 95% CI: 1.00, 1.18) and not convincingly associated with cancer mortality (HR: 0.95; 95% CI: 0.86, 1.04).
- Higher intake of animal-based foods was most clearly associated with higher mortality from infectious diseases (HR: 1.71; 95% CI: 1.24, 2.35) and endocrine causes (HR: 1.50; 95% CI: 1.22, 1.84).
- The study also showed an association with higher mortality from respiratory causes (HR: 1.16; 95% CI: 0.98, 1.38) and renal causes (HR: 1.24; 95% CI: 0.95, 1.61), but not statistically significantly so.
- Those with higher intake of ultra-processed foods were more likely male and black, much less likely vegan, less likely pesco vegetarian or lacto-ovo vegetarian.
- Those with high animal-based intake had higher prevalence of CVD, somewhat higher consumption of protein and sweetened beverages, were much less likely vegans, lacto-ovo vegetarians, or pesco vegetarians, and ate much more red meat, poultry, and fish.
Limitations Noted in the Document
- The study used a food frequency questionnaire (FFQ), which can lead to measurement errors.
- Diet was measured only once at the start of the study, and dietary habits may have changed over time.
- There is a potential for unadjusted or residual confounding.
- Findings may not be generalizable to different populations with different characteristics.
- The FFQ used in this study was not specifically designed to assess food processing.
Conclusion
The findings suggest that a high consumption of ultra-processed foods may be an important indicator of mortality. The study’s results indicated that the proportion of ultra-processed foods in the diet may be more important with respect to mortality than the proportion of animal-derived foods. The association between ultra-processed food intake and mortality was consistent even among vegetarians. The study also found that higher intake of red meat (substituting for plant-based food) was associated with higher mortality. This study adds to the evidence that ultra-processed foods are associated with all-cause mortality and emphasizes the importance of dietary quality in the context of vegetarian and nonvegetarian diets. Furthermore, the association of ultra-processed foods with mortality appeared stronger among those with chronic diseases at baseline, suggesting potential synergistic effects. The study’s findings emphasize the need for further investigation of the potential health effects of ultra-processed foods, with a focus on food processing as a key aspect of dietary quality. This approach could provide a way to approach dietary quality that is arguably easy to conceptualize and remember. The findings underscore the importance of considering both the degree of food processing and the sources of food in dietary recommendations.