Meat products consumption and risk for Alzheimer dementia and type 2 diabetes: a systematic review and meta-analysis of cohort studies

Alzheimer dementia (AD) and type 2 diabetes (T2D) are interrelated global public health problems, and the current epidemics of both AD and T2D are insulin resistance diseases. Thus, AD and T2D may share common risk factors such as an unhealthy diet, lifestyle, and obesity. Meat products is an important part of the diet of consumers worldwide. This systematic review and meta-analysis aims to assess and estimate the effect of meat products consumption on AD and T2D in humans. Web of Science, MEDLINE, PubMed, Cochrane Library, and Embase were searched from January 2012 to April 2024. 29 articles reported 32 cohort studies with 1,785,769 subjects, with 3,546 AD cases and 91,092 T2D cases that met the inclusion criteria and were included in our analysis. Consumption of various meat products increased the risk of T2D (HR = 1.19, 95% CI: 1.13 - 1.26, p = 0.000; I² = 88.5%), consumption of smoked, grilled/roasted and fried meat products was more likely to induce T2D (HR = 1.24, 95% CI: 1.18 - 1.30, p = 0. 000; I² = 76.1%), but was borderline significant for the risk of AD (HR = 1.11, 95% CI: 0.98 - 1.25, p = 0.094; I² = 58.8%), with consumption of mainly livestock and poultry products increasing the risk (HR = 1.21, 95% CI: 1.03 - 1.42, p = 0.017; I² = 66.8%). The association between meat products consumption and AD risk was influenced by meat type and sample size, while the risk of T2D was influenced by meat type, follow-up and sex. A daily intake of 27 g, 123 g and 170 g of livestock products increased the risk of T2D by 10%, 51% and 70% respectively, whereas the risk of T2D was reduced when the intake of various meat products was less than 23 g/d.