Dietary inflammatory potential, measured by the dietary inflammatory index (DII) has been linked to cognitive impairment. However, evidence was mostly driven by cross-sectional studies. This meta-analysis of prospective cohort studies aims to evaluate the relationship between DII and the risk of cognitive impairment, including mild cognitive impairment (MCI) and dementia.

We conducted a systematic search of PubMed, Web of Science, and Embase for studies published up to July 25, 2024. Prospective cohort studies with adults aged 18 years or older, without dementia at baseline, and reporting the incidence of cognitive impairment by DII category were included. Data were analyzed using a random-effects model to calculate pooled risk ratios (RRs) with 95% confidence intervals (CIs).

Nine prospective cohort studies with 266,169 participants were included. A high DII at baseline was associated with an increased risk of cognitive impairment during follow-up (RR: 1.34, 95% CI: 1.15 to 1.55, p < 0.001) with moderate heterogeneity (I² = 56%). Subgroup analyses revealed consistent associations across types of cognitive impairment (MCI, overall dementia, Alzheimer’s disease) and study characteristics (p for subgroup difference all >0.05). Sensitivity analyses confirmed the robustness of the results.

This meta-analysis suggests that a higher dietary inflammatory potential is independently associated with an increased risk of cognitive impairment. These findings underscore the potential impact of dietary inflammation on cognitive health and highlight the need for dietary strategies to mitigate cognitive decline risk.