Long-term study shows higher intake of ultraprocessed foods increases mortality risk

Key takeaways:

• Meat, seafood and poultry ready-to-eat foods had the strongest associations with mortality.
• The findings support limiting the consumption of certain ultraprocessed food types, researchers said.

Greater intake of ultraprocessed foods, like sugary drinks and ready-to-eat products, was associated with a slightly higher risk of all-cause mortality, according to results of a 30-study published in BMJ Open.

Previous research has shown that ultraprocessed foods (UPFs) are tied to higher risks of cancer and cancer-related mortality, as well as mortality in people with type 2 diabetes.

However, “few prospective cohort studies with a follow-up longer than 20 years have examined the association for all-cause mortality or cause-specific mortality, especially mortality due to cancer,” Zhe Fang, MBBS, MS, a PhD student in the department of epidemiology at Harvard T.H. Chan School of Public Health, and colleagues wrote. “High quality evidence from cohorts with a long follow-up is critical to inform dietary recommendations and food policies.”

For the study, the researchers assessed data on 74,563 female registered nurses enrolled in the Nurses’ Health Study (1984-2018) and 39,501 male health professionals from the Health Professionals Follow-up Study (1986-2018), all of whom had no prior history of cancer, CVD or diabetes at baseline. Participants completed questionnaires on medical and lifestyle information every 2 years and a food frequency questionnaire every 4 years.

Fang and colleagues also assessed diet quality with the Alternative Healthy Eating Index-2010, or AHEI, score.

Overall, there were 30,188 deaths among women and 18,005 deaths among men during median follow-up of 34 years and 31 years, respectively.

Fang and colleagues compared outcomes among participants in the lowest quartile of UPF intake, who had a median intake of three servings per day, with those in the highest quartile, who had a median intake of seven servings per day.

Compared with participants in the lowest quartile of UPF intake, those in the highest quartile had a 4% (HR = 1.04; 95% CI, 1.01-1.07) higher risk for all-cause mortality and a 9% (HR = 1.09; 95% CI, 1.05-1.13) higher risk for death not due to cancer or CVD, including an 8% (HR = 1.08; 95% CI, 1.01-1.17) higher risk for neurodegenerative deaths.

There were no significant associations between UPF intake and deaths related to cancer, CVD or respiratory disease, according to Fang and colleagues.

The absolute rate of all-cause mortality per 100,000 person years was 1,472 among participants in the lowest quartile of UPF intake and 1,536 among those in the highest quartile.

Meat, seafood and poultry-based ready-to-eat products had the highest associations with higher all-cause mortality (HR = 1.13; 95% CI, 1.1-1.16) and mortality due to individual causes other than CVD and neurodegenerative diseases (HRs ranged from 1.06 to 1.43) among nine UPF subgroups.

Other subgroups of UPFs that increased the risk of all-cause mortality included:

• sugar-sweetened and artificially sweetened beverages (HR = 1.09; 95% CI, 1.07-1.12);
• other UPFs mostly comprised of artificial sweeteners (HR = 1.08, 95% CI, 1.05-1.11);
• dairy-based desserts (HR = 1.07, 95% CI, 1.04-1.1); and
• breakfast foods excluding whole grains (HR = 1.04; 95% CI, 1.02-1.07).

“The associations between ultraprocessed food consumption and mortality were attenuated after we accounted for overall dietary quality,” Fang and colleagues wrote.

There were several limitations, according to the researchers. Because of the observational nature of the study, Fang and colleagues were unable to determine causality. In addition, generalizability of the findings was limited due to the cohorts being composed of predominantly non-Hispanic white health professionals.

The researchers advised against restricting all UPF consumption, but they noted that the findings “provide support for limiting consumption of certain types of ultraprocessed food for long-term health.”

“Future studies are warranted to improve the classification of ultraprocessed foods and confirm our findings in other populations,” they concluded.

References:

• Fang Z, et al. BMJ Open. 2024;doi:10.1136/bmj-2023-078476.
• 30-year US study links ultra-processed food to higher risk of early death.https://www.bmj.com/company/newsroom/30-year-us-study-links-ultra-processed-food-to-higher-risk-of-early-death/ . Published May 8, 2024. Accessed May 8, 2024.