Green tea contains catechins and theanine as major ingredients and has been reported to have various beneficial influences on human health. It is reported that the drinking green tea is inversely associated with serum homocysteine level in elderly. However the effect of green tea consumption on cognitive dysfunction is not clinically clarified. The purpose of this study is to investigate the effects of green tea consumption on homocysteine metabolism and cognitive dysfunction in elderly with impaired cognitive function.

Elderly people with impaired cognitive function go on increasing year by year with the coming aged society. Among them, the Alzheimer disease is a major cause of the illness, which is progressively worse, has no fundamental curable therapy, and induces the burdens of caregivers as well as the health insurance and national budget. Recently, homocysteine metabolism is reported to be related to atherosclerosis in aging, and draw attention as the etiology of cognitive dysfunction in elderly.

Green tea contains catechins and theanine as main ingredients. These components are reported to have anti-atherogenic action and effect on improving cognitive dysfunction. However, clinical evidence for homocysteine metabolism and cognitive dysfunction has not been clarified. Therefore, in this study, the investigators attempted to investigate the effects of green tea consumption on homocysteine metabolism and cognitive dysfunction in elderly with impaired cognitive function.

Inclusion Criteria:

• Obtained written informed consent before participation
• Possible to consume green tea powder
• Possessing cognitive dysfunction; MMSE score less than 30
• Possible not to take any supplement possessing anti-oxidizing effect; i.e., vitamin A, C, E, β-carotene

Exclusion Criteria:

• Possessing allergy to green tea
• Possessing severe cardiac, respiratory, renal, or hepatic dysfunction
• Possessing severe anemia
• Diagnosed as inadequate to participate in the study by doctor