Association between animal protein sources and risk of neurodegenerative diseases: a systematic review and dose-response meta-analysis.

Abstract

Current findings about the differential effects of various sources of dietary animal protein on the risk of neurodegenerative diseases are contradictory. The current meta-analysis was conducted to investigate the associations between intake of dietary animal protein sources and the risk of neurodegenerative diseases. PubMed, Scopus, Web of Science, and Google Scholar databases were searched systematically until October 2021. Prospective cohort studies exploring the association between consumption of animal protein sources and risk of neurodegenerative diseases in the general population were included. Among 10 571 identified studies, 33 prospective cohort studies met the eligibility criteria. Dietary fish consumption was associated with a reduced risk ofAlzheimer's disease (RR = 0.75; 95%CI, 0.57-0.97), dementia (RR = 0.84; 95%CI, 0.75-0.93), and cognitive impairment (RR = 0.85; 95%CI, 0.81-0.95). The risk of developingParkinson's disease was significantly higher among those in the highest vs the lowest intake categories of total dairy (RR = 1.49; 95%CI, 1.06-2.10) and milk (RR = 1.40; 95%CI, 1.13-1.73). Moreover, dietary intake of total dairy (RR = 0.89; 95%CI, 0.80-0.99), total meat (RR = 0.72; 95%CI, 0.57-0.90), and poultry (RR = 0.82; 95%CI, 0.68-0.99) was significantly associated with a lower risk of cognitive impairment. A linear dose-response meta-analysis revealed that each 200-g increase in total daily dairy intake was associated with an 11% higher risk ofParkinson's disease and a 12% lower risk of cognitive impairment. Furthermore, there was a strong linear association between fish consumption and reduced risk of dementia. Dairy consumption is associated with an increased risk ofParkinson's disease, but a higher intake of fish may be associated with lower risk of neurodegenerative disease. Future well-controlled, randomized clinical trials are essential to validate the present findings. PROSPERO registration no. CRD42021281887.