Ultraprocessed foods and beverages are processed industrially and contain little to no intact foods; they are composed primarily of ingredients extracted from foods and include nonculinary substances and artificial additives meant to enhance shelf life and palatability. Ultraprocessed foods are high in added sugar, refined carbohydrates, saturated and trans fats, and sodium, and they contain low amounts of fiber, protein, and micronutrients.
Consumption of ultraprocessed foods is on the rise in the United States and worldwide. Previous studies have examined the link between consumption of ultraprocessed food and cardiovascular diseases, all-cause mortality, and cancers. There are few available data on the impact of consumption of ultraprocessed food on renal health.
Shutong Du, MHS, and colleagues conducted a prospective cohort study designed to examine the association between ultraprocessed food consumption and incident chronic kidney disease (CKD). Results of the study were reported in the American Journal of Kidney Diseases [2022;80(5):589-598].
The study included 14,769 adults without CKD at baseline in the ARIC (Atherosclerosis Risk in Communities) study. The study exposure was consumption of ultraprocessed foods (servings per day), calculated using dietary data collected via a food frequency questionnaire at visit 1 and visit 3.
The primary outcome of interest was incident CKD, defined as estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2, accompanied by ≥25% decline in eGFR, CKD-related hospitalization or death, or kidney failure requiring renal replacement therapy.
The association between consumption of ultraprocessed foods and CKD was assessed using multivariable-adjusted Cox proportional hazards models. The shape of the association was examined using restricted cubic splines.
Of the 14,769 patients included in the current analysis, 55.1% were female and 25.2% were Black. Mean age was 54.1 years and mean body mass index (BMI) was 27.6 kg/m2. More than two-fifths had an education level higher than a high school diploma (44.4%) and never smoked tobacco (41.5%). More than half never drank alcohol (56.7%).
Participants were stratified into quartiles based on mean energy-adjusted ultraprocessed food consumption. In quartile 4, mean energy-adjusted ultraprocessed food consumption was 8.4 servings per day, compared with 3.6 servings per day in quartile 1. Participants in the highest quartile of ultraprocessed foods were younger, more likely to be White and former smokers, and have obesity and lower levels of physical activity. Those who consumed more ultraprocessed foods also had lower overall diet quality.
There were associations between ultraprocessed food consumption and lower intake of protein, cholesterol, fiber, and micronutrients including niacin, vitamin A, vitamin B6, vitamin B12, calcium, phosphorus, magnesium, and potassium, and a higher intake of fat (total, saturated, monounsaturated, and polyunsaturated). Those in the highest quartile had lower consumption of fruits and vegetables, and higher consumption of sugar-sweetened beverages. The food groups that contributed the most to consumption of ultraprocessed foods were sugar-sweetened beverages (27%), margarine (18%), bakery goods (15%), and ultraprocessed meats (11%).
The follow-up period was a median of 24 years. During the follow-up period, there were 4859 cases (34.0%) of incident CKD. Among those in the highest quartile of ultraprocessed food consumption the incidence rate of incident CKD was 12% higher (16.5; 95% CI, 15.6-17.4 per 1000 person-years) compared with those in the lowest quartile (14.7; 95% CI, 13.9-15.5 per 1000 person-years). There was an association between higher intake of ultraprocessed foods and a higher risk of incident CKD; results were consistent across different models.
In model 1, adjusting for age, sex, race-center, and total energy intake, those in the highest quartile had a 27% higher risk of incident CKD compared with those in the lowest quartile (hazard ratio [HR], 1.27; 95% CI, 1.17-1.37). Results were similar in the main model (model 2) that was further adjusted for education level, smoking status, and physical activity (HR, 1.24; 95% CI, 1.15-1.35 for quartile 4 vs quartile 1). Following additional adjustment for potential mediators (model 3), results were attenuated, but the association between ultraprocessed food consumption and incident CKD remained statistically significant (HR, 1.16; 95% CI, 1.07-1.26 for quartile 4 vs quartile 1).
There was a significant association between each additional serving of ultraprocessed food consumed per day and a 5% higher risk of incident CKD, using the composite definition of CKD (model 2 HR, 1.05; 95% CI, 1.04-1.07; P<.001), as well as the visit-based definition of CKD (model 2 HR, 1.05; 95% CI, 1.03-1.07; P<.001).
There was a significant association between replacing one serving per day of ultraprocessed food with minimally processed food and a 6% lower risk of incident CKD (HR, 0.94; 95% CI, 0.93-0.96; P<.001). There was also an association between higher intake of unprocessed or minimally processed foods and a lower risk of CKD. In the main model, those in the highest quartile of minimally processed food intake has a 10% lower risk of incident CKD compared with those ion the lowest quartile (model 2 HR, 0.90; 95% CI, 0.83-0.98 for quartile 4 vs quartile 1; P=.003).
In citing limitations to the study findings, the researchers included the use of self-reported dietary data that are prone to measurement error and recall bias, use of a food frequency questionnaire that was not specifically designed to collect data on consumption of ultraprocessed foods, and the observational design that may have resulted in findings of reverse causality.
In summary, the authors said, “In this large prospective cohort of middle-aged adults, higher ultraprocessed food consumption was associated with a higher risk of incident CKD. This association was independent of CKD risk factors, was not entirely explained by potential mediating health conditions and diet quality, and was consistent across subgroups of the study population by sex, race, BMI, diabetes status, and hypertension status. Given the rise of ultraprocessed foods in the global food supply, our study provides further support to avoid ultraprocessed foods and to replace ultraprocessed foods with minimally processed or unprocessed foods. These findings should be confirmed in other settings and other populations, and further studies should explore the specific mechanisms by which ultraprocessed foods may be harmful to the kidneys.”
Takeaway Points
- Researchers reported results of a prospective cohort study designed to examine the impact of consumption of ultraprocessed foods on the risk of incident chronic kidney disease (CKD).
- There was an independent association between higher consumption of ultraprocessed foods and a higher risk of incident CKD in a general population.
- The association remained even after adjustment for known CKD risk factors and across subgroups by sex, race, body mass index, and diabetes and hypertension status.
