A comprehensive review on the prevention and regulation of Alzheimer’s disease by tea and its active ingredients

Abstract

Alzheimer’s disease (AD) has brought a heavy burden to society as a representative neurodegenerative disease. The etiology of AD combines multiple factors, concluding family, gender, head trauma, diseases and social psychology. There are multiple hypotheses explaining the pathogenesis of AD such as β-amyloid (Aβ) deposition and tau hyperphosphorylation, which lead to extracellular amyloid plaques and neurofibrillary tangles in neurons. The existing therapeutic drugs have several disadvantages including single target, poor curative effect, and obvious side effects. Tea contains many bioactive components, such as tea polyphenols (TPP), L-theanine (L-TH), tea pigment, tea polysaccharides and caffeine. The epidemiological investigations have shown that drinking tea can reduce the risk of AD. The mechanisms of tea active ingredients in the prevention and regulation of AD includes reducing the generation and aggregation of Aβ; inhibiting tau aggregation and hyperphosphorylation; inhibiting neuronal apoptosis and regulate neurotransmitters; relieving oxidative stress and neuroinflammation as well as the regulation of intestinal flora. This review summarizes the different signaling pathways that tea active ingredients regulate AD. Furthermore, we propose the main limitations of current research and future research directions, hoping to contribute to the development of natural functional foods based on tea active ingredients in the prevention and treatment of AD.

HIGHLIGHTS

• Natural AD-modulating active ingredients in tea have been summarized.

• Influences of drinking tea or tea active ingredients on AD are reviewed.

• Main regulating mechanisms of tea active ingredients on AD are explained.

• The main limitations of current research and future directions are proposed.

Keywords:

• Tea active ingredients
• Alzheimer’s disease
• neuroprotection
• β-amyloid
• inflammation
• intestinal flora

Acknowledgements

The authors are grateful for financially sponsored by the fellowship of China Postdoctoral Science Foundation (2021M702140), Shanghai Postdoctoral Excellence Program (2021224), Program of Shanghai Academic/Technology Research Leader (20XD1433500) and Shanghai Agricultural Leading Talent Program, the National Natural Science Foundation of China (32172223).

Authors’ contributions statement

Yi Huang and Yang Wei: Conceptualization, Writing-Original draft preparation and Revision (contributed equally to this work). Jia Xu: Investigation and Methodology. Xinlin Wei: Supervision, Reviewing and Editing.

Disclosure statement

The authors declare no competing financial interest.

Table 5. Effects of different teas or tea active ingredients on intestinal microbiota.

Funding

The authors are grateful for financially sponsored by the fellowship of China Postdoctoral Science Foundation (2021M702140), Shanghai Postdoctoral Excellence Program (2021224), Program of Shanghai Academic/Technology Research Leader (20XD1433500) and Shanghai Agricultural Leading Talent Program, the National Natural Science Foundation of China (32172223).