Villoz, Fanny; Filippini, Tommaso; Ortega, Natalia; Kopp-Heim, Doris; Voortman, Trudy; Blum, Manuel R; Del Giovane, Cinzia; Vinceti, Marco; Rodondi, Nicolas; Chocano-Bedoya, Patricia (2024). Dairy intake and risk of cognitive decline and dementia: A systematic review and dose-response meta-analysis of prospective studies. Advances in nutrition, 15(1), p. 100160. Elsevier 10.1016/j.advnut.2023.100160
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BACKGROUND
Dairy intake may influence cognition through several molecular pathways. However, epidemiologic studies yield inconsistent results, and no dose-response meta-analysis has been conducted yet.
OBJECTIVE
We performed a systematic review with dose-response meta-analysis about the association between dairy intake and cognitive decline or incidence of dementia.
METHODS
We investigated prospective studies with a follow-up ≥6 months on cognitive decline or dementia incidence in adults without known chronic conditions through a systematic search of Embase, Medline, Cochrane Library, Web of Science and Google Scholar from inception to July 11, 2023. We evaluated dose-response association using a random-effects model.
RESULTS
We identified 15 eligible cohort studies, with over 300,000 participants and a median follow-up of 11.4 years. We observed a negative non-linear association with cognitive decline/dementia incidence and dairy intake as assessed through quantity of consumption, with the nadir at approximately 150 g/day (RR=0.88, 95% CI 0.78-0.99). Conversely, we found an almost linear negative association when we considered frequency of consumption (RR for linear trend 0.84, 95% CI 0.77-0.92 for 1 time/day increase of dairy products). Stratified analysis by dairy products showed different shape of the association with linear inverse relationship for milk intake, while possibly non-linear for cheese. The inverse association was limited to Asian populations characterized by generally lower intake of dairy products, compared with the null association reported by European studies.
CONCLUSION
Our study suggests a non-linear inverse association between dairy intake and cognitive decline or dementia, also depending on dairy types and population characteristics, although the heterogeneity was still high in overall and several subgroup analyses. Additional studies should be performed on this topic, also including a wider range of intake and types of dairy products, to confirm a potential preventing role of dairy intake on cognitive decline and identify ideal intake doses.
PROSPERO'S REGISTRY NUMBER
CRD42020192395.
STATEMENT OF SIGNIFICANCE
This systematic review and meta-analysis identified 15 prospective observational studies evaluating the role of dairy on cognitive function. Our results suggest that dairy might be associated with lower risk of cognitive decline or dementia, but that the relation seems non-linear with also differences by sex, age, region of origin, level of intake and type of dairy products.