Among 7,113 US adults with chronic kidney disease in NHANES (2005-2018), those in the highest quartile of the dietary inflammatory index (DII) had a 23% higher all-cause mortality risk than those in the lowest (HR 1.23; 95% CI 1.07-1.42) after full adjustment. The relationship was linear across the DII range, with no evidence of a threshold. DII scores were not associated with cardiovascular or cancer mortality, and the effect appeared stronger in participants with lower body weight.
The all-cause signal fits a broader literature linking pro-inflammatory eating patterns (high in refined grains, processed meat, saturated fat; low in vegetables, fruit, fibre, omega-3s) to worse outcomes, and CKD is a plausible setting where chronic inflammation amplifies risk. The null cardiovascular and cancer findings deserve caution rather than interpretation: cause-specific deaths were likely too few to detect modest effects. The main limitations are structural. NHANES diet data rest on one or two 24-hour recalls, which misclassify habitual intake; CKD staging relies on single-visit measurements; and residual confounding is likely, since sicker patients may eat less and lose weight, which could also explain the stronger effect in lighter participants (reverse causation). Dietary advice in CKD also involves competing concerns such as potassium and phosphorus restriction, which the DII does not capture. This is a confirmatory observational result: it supports emphasising plant-forward, minimally processed diets in kidney disease, but only trials can show that lowering DII improves survival. Patients should discuss dietary changes with their nephrologist or renal dietitian.