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.

The objective of this study was to evaluate the effects of chilling rate on porcine meat quality from the perspective of proteome using data independent acquisition (DIA)-based quantitative proteomic strategy. M. longissimus thoracis et lumborum (n = 9) was assigned randomly to the control group (3.72 ℃/h), very fast chilling-Ⅰ group (VFC-Ⅰ, 9.31 ℃/h) and VFC-Ⅱ group (14.43 ℃/h). The DIA was used to analyze the difference in proteins under different chilling rates. Results showed that tenderness was improved significantly in meat at the chilling rate of 14.43 ℃/h. Seventy-nine differential abundant proteins (fold change >1.5, P <0.05), including 46 up-regulated and 33 down-regulated proteins, were identified and mainly involved in carbon metabolism, pyruvate metabolism and proteasome pathways. These pathways indicated that VFC delayed cell metabolism and glycolysis by down-regulating the expression of metabolic enzymes. The tenderness was improved by up-regulating the expression of proteasome and m-calpain.

The degradation of titin could make the myofibrillar fragmentation to improve meat tenderization during postmortem. This study aimed to investigate effect of phosphorylation on titin degradation. Protein kinase A (PKA) and alkaline phosphatase (AP) were added to crude titin extracted from ovine longissimus lumborum (LL) muscles. Phosphorylated/dephosphorylated titin were incubated with μ-calpain at 4 ℃ for 2 days. Results showed titin in AP group started degradation earlier than that in PKA and control groups. There were 20, 16 and 12 phosphorylated sites identified by iTRAQ in the PKA, control and AP group, respectively. 3D structure of dephosphorylated titin fragment was simulated and its molecular dynamics trajectory analysis was performed using Discovery Studio^TM. The dihedral angle in AP group was less and the dephosphorylated fragment had a higher kinetic energy and total energy. We suggested that changes caused by AP treatment might make titin unstable, which easily degraded by μ-calpain.