Study associates higher mortality with eating lots of ultra-processed foods, red meat
Loma Linda University Health researchers say high consumption of ultra-processed foods and, separately, high consumption of red meat may be important mortality indicators. Their recently published study adds to a growing body of knowledge about how ultra-processed foods and red meat impact human health and longevity.
Compared to past literature analyzing ultra-processed and animal-based foods' health impacts, this study included one of the largest cohorts, with over 77,000 participants. It also considered a diverse array of diets, including vegetarian and non-vegetarian. As a result, outcomes provided new insights about ultra-processed foods as a common denominator of mortality across vegetarians and non-vegetarians, says Gary Fraser, MBChB, Ph.D., a study author, and professor at Loma Linda University School of Medicine and School of Public Health.
"Our study addresses the question of what can make a vegetarian diet healthy or unhealthy," Fraser says. "It seems that the proportion of ultra-processed foods in someone's diet is actually more important with respect to mortality than the proportion of animal-derived foods they eat, the exception being red meat."
Fraser says the study exposes how it is possible to be a "bad vegetarian or a good non-vegetarian" because it isolates the health impacts of processed foods in the diet—whether it's vegetarian or not. Results revealed that vegetarians who ate a lot of processed foods as part of their diets faced a similar proportionate increase in mortality outcomes as non-vegetarians who ate a lot of processed foods in their diets.
The study, "Ultra-processed food intake and animal-based food intake and mortality in the Adventist health study-2," published in the American Journal of Clinical Nutrition, assesses the mortality risks of two dietary factors independent of each other:
- the proportion of the diet composed of ultra-processed foods as opposed to less processed foods; examples of ultra-processed foods include soft drinks, certain meat analogs, and candy.
- the proportion of the diet from animal-based foods (meats, eggs, and dairy) as opposed to plant-based foods.
Seven LLU researchers gathered data from an observational prospective cohort study in North America, recruited from Seventh-day Adventist churches, comprising of 77,437 female and male participants. Participants completed a frequency food questionnaire including over 200 food items to describe their diets. They also provided other health-related and demographic information about themselves, including sex, race, geographic region, education, marital status, rate of tobacco and alcohol use, exercise, sleep, BMI, and comorbid conditions with cardiovascular disease or diabetes.
Researchers then analyzed participants' health and demographic information in conjunction with their mortality data, provided by the National Death Index, for a mean timeframe of about seven and a half years. Next, researchers used a statistical model to help them consider each variable independently of others and produce a cause-specific mortality analysis.
They adjusted their statistical model to focus on ultra-processed food intake irrespective of other factors like animal-food consumption or age. In doing so, Fraser and co-authors found that people who obtained half of their total calories from ultra-processed foods faced a 14% increase in mortality compared to people who received only 12.5% of their total calories from ultra-processed foods.
Study authors report that high consumption levels of ultra-processed foods were associated with mortality related to respiratory, neurologic, and renal conditions—particularly Alzheimer's disease, Parkinson's disease, and chronic obstructive pulmonary disease (even when restricted to people who never smoked). However, high ultra-processed food consumption was not associated with mortality from cardiovascular disease, cancer, or endocrine conditions.
Results did not reveal an association between mortality and dietary intake of total animal-based foods. Once researchers parsed animal-based foods into sub-categories, however, they found a statistically significant 8% increase in the mortality risk associated with moderate (approximately 1 ½ oz per day) consumption of red meat compared to no red meat.
Overall, Fraser says the study demonstrated how greater consumption of ultra-processed foods was associated with higher all-cause mortality, even in a health-conscious Adventist population with many vegetarians. Such findings of ultra-processed food consumption and mortality provide a "helpful confirmation of what people expected," he says.
The study calls for further research into the specific health effects of ultra-processed foods consumption in humans. While research endeavors continue to deepen understanding of how ultra-processed foods impact our health, Fraser advises avoiding consuming them at high levels.
"If you're interested in living longer or to your maximal potential, you'd be wise to avoid a diet filled with ultra-processed foods and replace them with less processed or unprocessed foods," Fraser says. "At the same time, avoid eating a lot of red meat. It's as simple as that."
More information: Michael J Orlich et al, Ultra-processed food intake and animal-based food intake and mortality in the Adventist Health Study-2, The American Journal of Clinical Nutrition (2022). DOI: 10.1093/ajcn/nqac043