Ultra-Processed Food and Kidney Disease: What a New Study Found

On September 2, 2026, a prospective study in the Clinical Journal of the American Society of Nephrology reported that older adults consuming the highest amounts of animal-sourced ultra-processed foods faced a 37% higher risk of incident chronic kidney disease. Total ultra-processed food intake carried a 26% higher risk, whereas plant-sourced varieties showed no significant association across intake thirds.

Key takeaways:

• A prospective study in CJASN evaluated 2,661 older adults over a median follow-up of 6.8 years and tracked incident chronic kidney disease.
• Participants in the highest third of animal-sourced ultra-processed food intake experienced a 37% higher risk of chronic kidney disease compared to the lowest third.
• Plant-sourced ultra-processed foods showed no statistically significant risk elevation across intake thirds.
• Diets highest in minimally processed foods were associated with a 20% lower risk of developing kidney disease.
• Because the study was observational, it cannot prove direct causation or isolate individual chemical additives.

What happened

On September 2, 2026, a research team including Hill CM, Rebholz CM, Psaty BM, and Kim H published new findings in the Clinical Journal of the American Society of Nephrology (CJASN). The study evaluated dietary patterns from the Cardiovascular Health Study, an established prospective cohort of community-dwelling older American adults, to examine how industrial food processing tracks with renal health.

The authors analyzed 2,661 participants aged 65 or older. Dietary intake was captured using food frequency questionnaires administered during the 1989 to 1990 and 1995 to 1996 study visits. As reported in the CJASN study indexed on PubMed (full paper via DOI 10.2215/cjn.0000001207), the researchers classified reported items using the Nova food classification framework and then divided ultra-processed foods into plant-sourced and animal-sourced groups.

Over a follow-up period extending up to 18 years, with a median observation time of 6.8 years, the authors tracked incident chronic kidney disease, defined as an estimated glomerular filtration rate (eGFR) falling below 60 mL/min/1.73 m2, as well as eGFR trajectory over time.

What changed?

While previous nutritional studies have evaluated overall ultra-processed food consumption, this research separated ultra-processed items by origin to test whether plant-derived and animal-derived formulations carry different risks.

When comparing participants in the highest third of intake against those in the lowest third, total ultra-processed food consumption was associated with a hazard ratio of 1.26 (95% CI 1.08 to 1.47), representing a 26% increased risk. Animal-sourced ultra-processed foods showed the strongest association, with a hazard ratio of 1.37 (95% CI 1.17 to 1.60), reflecting a 37% higher risk of incident chronic kidney disease.

Plant-sourced ultra-processed foods showed a hazard ratio of 1.07 (95% CI 1.01 to 1.13) when evaluated per standard deviation increase, but the relationship was not statistically significant when comparing thirds of intake. Conversely, participants in the highest third of minimally processed food intake had a hazard ratio of 0.80 (95% CI 0.69 to 0.95), or approximately 20% lower risk.

Statistically replacing 3 servings per day of minimally processed foods with ultra-processed alternatives was only weakly associated with kidney disease incidence, yielding a hazard ratio of 1.02. Furthermore, the researchers observed no association between ultra-processed food intake and the rate of eGFR change over time, and risk estimates were attenuated when models accounted for the competing risk of death.

Who is affected?

This study specifically tracked adults aged 65 and older living in the United States. Chronic kidney disease is common in this age group, which is one reason the Cardiovascular Health Study was a natural place to look.

Because the cohort was limited to older individuals, the investigators emphasized that more work is needed in younger populations before these specific risk ratios can be generalized across all demographics.

Additionally, the study assessed diets through historical food frequency questionnaires completed in the 1990s. The formulation of packaged groceries has shifted substantially over the intervening decades, so today's versions of the same foods may differ from what participants ate.

What it means for shoppers

For grocery shoppers navigating packaged goods, the study underscores the importance of looking past marketing claims on the front of boxes and cartons. The paper evaluated broad categories rather than single branded items, distinguishing minimally processed staples from highly formulated industrial preparations.

Generic categories of animal-sourced ultra-processed foods include items like processed meats and certain highly processed dairy formulations. These products often combine animal proteins with industrial emulsifiers, texturizers, and preservatives to prolong shelf stability and enhance palatability.

Shoppers aiming to reduce their intake of heavily processed animal foods can check the ingredient deck for signs of industrial reformulation:

• Check whether whole meats or dairy ingredients are combined with texturizing starches, protein isolates, or flavor enhancers.
• Review the Nutrition Facts panel for sodium levels, checking how a single serving fits into your daily routine.
• Compare flavored animal-derived products against unflavored, single-ingredient equivalents like plain milk, raw meats, or plain yogurt.
• Watch for front-of-pack claims promoting high protein that mask lengthy industrial additive lists.

As regulators debate mandatory packaging disclosures, such as those discussed in our analysis of how the FDA's Front-of-Package Nutrition Box Is Still Not Final, shoppers currently rely on independent reading of the back-of-package panel.

The background

Chronic kidney disease often develops silently, progressing over years before formal diagnosis through routine blood filtration tests.

As general dietary background, the NIH's National Institute of Diabetes and Digestive and Kidney Diseases advises people with chronic kidney disease to watch sodium and phosphorus, because damaged kidneys cannot remove phosphorus from the blood as well as healthy kidneys, and it notes that phosphorus additives in packaged foods are a major source. That is general guidance for people who already have CKD, not a finding of this study. However, the CJASN study did not identify which individual ingredients or nutrients drove the observed risk. The paper did not isolate phosphate additives, sodium, saturated fat, or specific stabilizers as the causal mechanism.

Ultra-processed food as a category is not banned by the FDA or in the EU; rules still target specific additives and nutrients. US agencies have started work on a federal definition of ultra-processed food, and some states are exploring labels, such as California's proposed non-ultraprocessed seal.

Scientific study of the Nova framework has faced continuous discussion. Critics note that grouping items based on processing markers can sometimes obscure basic nutritional differences, while proponents argue that industrial processing introduces physical matrices and additive combinations that basic nutrient tallies fail to capture.

What to watch next?

The authors conclude that additional work is needed in younger populations. Whether cutting animal-sourced ultra-processed foods changes kidney outcomes would take an intervention trial to show; this study cannot answer it.

A central limitation of the CJASN study is its observational nature: it can demonstrate an association, but it cannot prove direct causation. Dietary data was self-reported decades ago, and the study did not measure individual additive concentrations or post-market formulation changes. Future investigations will need to track exact chemical additives, biological markers of inflammation, and metabolic outcomes concurrently.

In the meantime, the practical takeaway is modest: more minimally processed food was associated with lower risk, and the ingredient list is the best place to see how processed a product is. Scan a label with the Aurascan app to see each ingredient explained with the evidence behind it.