Higher consumption of ultra-processed foods linked to elevated mortality risk

By Pooja Toshniwal PahariaReviewed by Lily Ramsey, LLMMay 9 2024

In a recent study published in BMJ, researchers investigated the relationship between ultra-processed food (UPF) intake and all-cause and cause-specific death in the United States (US).

​​​​​​​Study: Association of ultra-processed food consumption with all cause and cause specific mortality: population based cohort study. Image Credit: Daisy Daisy/Shutterstock.com

Background

Ultra-processed foods, which are low-quality, high-energy density, ready-to-cook/heat industrial formulations, dominate the food supply in high-income countries and are increasingly common in middle-income nations.

These foods frequently have added sugars, salt, saturated fats, trans fats, processed carbs, and poor fiber. They may also include dangerous additives and pollutants. 

Large-scale cohort studies suggest that ultra-processed foods have negative health impacts, such as overweight or obesity, cardiovascular disease, type 2 diabetes, colon cancer, metabolic syndrome, depression, postmenopausal breast cancer, and increased any-cause mortality.

However, there is insufficient research on the effect of UPF intake on mortality outcomes. High-quality evidence is critical for making dietary recommendations and developing food policy.

About the study

In the present population-based cohort study, researchers investigated whether UPF consumption increases any-cause mortality or specific-cause mortality, especially mortality due to cancer.

The researchers conducted the study among female Nurses’ Health Study (NHS, 1984–2018, across 11 states) participants aged 30-55 years and male Health Professionals Follow-up Study (HPFS, 1986–2018) participating individuals aged 40–75 years.

Study participants included 74,563 females and 39,501 males without a history of cardiovascular disease, diabetes, or cancer, excluding those with implausible calorie intakes or missing UPF intake data.

The participants completed questionnaires concerning their lifestyle habits and medical history every two years. The researchers assessed UPF intake using the NOVA classification and semi-quantitative food frequency questionnaires in four-year gaps. They evaluated dietary quality using the Alternative Healthy Eating Index-2010 (AHEI) scores.

Follow-up time accrued from the questionnaire return date to that of death or follow-up period termination (June 30, 2018, for the NHS and January 31, 2018, for HPFS), whichever occurred first.

Deaths were notified by offspring through the post office in the returned questionnaires or identified through the National Death Index and vital state records. The team identified the cause of death using the International Classification of Diseases, eighth revision (ICD-8) codes.

The researchers performed multivariate Cox proportional hazards regression modeling to determine hazard ratios (HR) for the relationship between UPF intake and any-cause deaths and specific-cause deaths due to cardiovascular disease, cancer, and others, including neurodegenerative and respiratory causes.

Study covariates included race, ethnicity, smoking habits, alcohol intake, physical activity, body weight, marital status, family history of diabetes, cardiovascular disease, cancer, menopausal status, and hormone usage after menopause.

Results

In total, 48,193 deaths, including 18,005 males and 30,188 females, were documented over median follow-ups of 31 and 34 years, respectively.

Stratifying by cause, 13,557 were cancer-related, 11,416 were due to cardiovascular disease, 3,926 deaths had respiratory causes, and 6,343 had neurodegenerative causes.

Individuals with higher UPF intake were physically inactive and younger, with elevated body mass index values, lower AHEI scores, and an increased likelihood of smoking.

Compared to individuals in the lowermost quarter of the UPF intake median (a median of three servings per day), those in the uppermost quarter (seven servings per day) showed a 4.0% higher any-cause mortality rate (HR, 1.0) and 9.0% higher deaths due to causes excluding cardiovascular disease and cancer (HR, 1.1).

Any-cause deaths among individuals from the lowermost and uppermost quarters were 1,472 and 1,536 per 100,000 individual years, respectively.

Meat, seafood, and poultry-derived ready-to-cook foods (such as processed meats) consistently showed robust associations with death, with HR values between 1.1 and 1.4.

Artificially- and sugar-sweetened fluids (HR, 1.1), dairy desserts (HR, 1.1), and UPF breakfast foods (HR, 1.0) also contributed to higher any-cause mortality. 

However, there were inconsistent relationships between UPF intake and death within every quarter of diet quality based on the AHEI scores.

In contrast, improved dietary quality lowered mortality outcomes in every quarter of UPF intake. The associations between UPF consumption and any-cause mortality were stronger among individuals not currently smoking and those consuming less alcohol.

The study found that eating more ultra-processed meals is associated with a slight increase in all-cause mortality, primarily due to poultry/seafood/meat-type ready-to-cook goods, sugary beverages, dairy-based desserts, and ultra-processed breakfast dishes.

Thus, careful consideration is required when including UPFs in dietary standards, and their intake should be limited for long-term health reasons. 

Nevertheless, the impact of dietary quality was more profound than UPF intake on mortality. Further research might enhance UPF evaluation and corroborate the findings across different groups.