Green Tea Intake and Risks for Dementia, Alzheimer's Disease, Mild Cognitive Impairment, and Cognitive Impairment: A Systematic Review.

Nutrients. 2019;11(5)
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Around 50 million people worldwide suffer from dementia, with 10 million new cases being diagnosed every year. Diet may play a role in the prevention of dementia. In this systematic review, the authors reviewed eight previous studies examining the effects of green tea on dementia. Six of the eight studies supported a preventative effect of green tea intake. The authors suggested that green tea might positively influence biological mechanisms such as oxidative stress, inflammation, accumulation of plaques in the brain and the maintenance of healthy blood vessels. The authors concluded that green tea intake might reduce the risk for dementia, Alzheimer's disease, mild cognitive impairment, or cognitive impairment, but further studies are needed.

Abstract

Dementia has become a major issue that requires urgent measures. The prevention of dementia may be influenced by dietary factors. We focused on green tea and performed a systematic review of observational studies that examined the association between green tea intake and dementia, Alzheimer's disease, mild cognitive impairment, or cognitive impairment. We searched for articles registered up to 23 August 2018, in the PubMed database and then for references of original articles or reviews that examined tea and cognition. Subsequently, the extracted articles were examined regarding whether they included original data assessing an association of green tea intake and dementia, Alzheimer's disease, mild cognitive impairment, or cognitive impairment. Finally, we included three cohort studies and five cross-sectional studies. One cohort study and three cross-sectional studies supported the positive effects of green tea intake. One cohort study and one cross-sectional study reported partial positive effects. The remaining one cohort study and one cross-sectional study showed no significant association of green tea intake. These results seem to support the hypothesis that green tea intake might reduce the risk for dementia, Alzheimer's disease, mild cognitive impairment, or cognitive impairment. Further results from well-designed and well-conducted cohort studies are required to derive robust evidence.

Lifestyle medicine

Fundamental Clinical Imbalances : Neurological ; Immune and inflammation
Patient Centred Factors : Mediators/Dementia
Environmental Inputs : Nutrients
Personal Lifestyle Factors : Nutrition
Functional Laboratory Testing : Not applicable
Bioactive Substances : Green tea

Methodological quality

Allocation concealment : Not applicable
Publication Type : Journal Article ; Systematic Review

Metadata