Association of the dietary inflammatory index with multi-organ biological age acceleration

In recent years, the dietary inflammation index (DII) has become an important tool widely used to assess the inflammatory potential of an individual's diet. The aim of this study was to investigate the relationship between the DII and the biological aging of multiple organs (heart, liver, and kidneys) in American adults.

A cross-sectional study was performed using data from the National Health and Nutrition Examination Survey of American adults between 2003 and 2018. The DII was calculated using 28 nutrients from daily dietary intake. The biological age (BA) of the heart, liver, and kidneys was calculated using the Klemera-Doubal method. ∆ age was determined by assessing the difference between an individual's estimated BA and their actual age.

A total of 14,873 individuals were included; the mean (SD) age was 45.59 (16.54) years, and 7,639 (51.44%) were female. In the fully adjusted final model, the highest tertile of the DII was significantly correlated with the Δ age of each organ (cardiovascular Δ age: β = 0.87, liver Δ age: β = 2.86, kidney Δ age: β = 0.80; all p values ≤ 0.01). The DII was positively correlated with the cardiovascular (r = 0.06) (p ≤ 0.01), liver (r = 0.16), and kidney (r = 0.03) Δ age (all p ≤ 0.01). However, sensitivity analyses confirmed only significant positive associations of the DII with the heart and liver Δ age. The log-transformed and standardized (z score) values of either C-reactive protein or high-sensitivity CRP and white blood cell count were demonstrated to mediate the relationships between the DII and heart, liver, and renal Δ age.

Our analyses demonstrated significant associations between an elevated DII and accelerated biological aging in both the cardiovascular and hepatic systems, albeit with modest effect sizes that may reflect both genuine biological relationships and inherent limitations of cross-sectional dietary assessment. Prospective studies with repeated measures are warranted to validate these associations and elucidate the underlying physiological mechanisms.