Does drinking green tea prevent disability? (2/13/12)
Food-Drugs and Health
Many foods are also drugs, and have been effectively used for thousands of years. Green tea is one. Green tea has been credited with lowering stroke, osteoporosis, and cognitive failure risks. A new Japanese longitudinal study of green tea showed decreased disability from use of green tea – with a clear dose response curve. The more people drank, the lower the risk of disability.
The report in the American Journal of Clinical Nutrition was important for several reasons:
- 14,000 people were surveyed over 3 years.
- Participation rates were high.
- Criteria for long term disability are the same across Japan and follow long developed, standardized criteria.
- Estimation of green tea use was potentially more accurate than in many studies.
- The group studied was relatively healthy.
Green tea users, as a group, had more healthy characteristics and behaviors than those who did not drink green tea. They included:
Less symptoms of psychological distress
Less history of heart attack and stroke
Ate more meat, fish, green and yellow vegetables
Had better cognitive activity
More social support and social engagement
They were also:
More likely to be smokers
More likely to drinkers
Ate more sweets
When all these statistical measures were controlled, green tea still appeared to protect against disability. Those who drank perhaps one cup a day had about 90% the risk of those who did not drink; those who drank 5 cups or more a day saw their disability risk drop to 67%.
Why Would Green Tea Work?
Foods contain thousands of different substances. Separating out which are “beneficial” is much harder than supplement manufacturers let you know.
There are many “anti-oxidants” in green tea. There are also high levels of caffeine and polyphenols.
Studies of foods also have a difficult time separating the effects of cuisine versus individual food ingredients – thousands of substances in one food will interact with thousands of substances in other foods. It’s a bit easier looking at green tea, black tea and coffee in part because they are clearly drugs, and people are generally more accurate in knowing their level of consumption.
Should I Drink Green Tea?
Green tea may interfere with other drugs. Caffeine may “rev people up” and also cause them to get nervous. Middle aged drinkers may need to keep bathrooms close at hand – especially among males with burgeoning prostates.
Yet there is much evidence for advantages of the most common food-drugs that are globally imbibed – coffee, green tea, and black tea. The positive health effects may relate to their caffeine content, and the many other substances they contain.
Lots of coffee drinking seems to decrease the risk of diabetes and Parkinsonism. Black tea may do the same. Green tea may have other advantages over other beverages in one area, but not in another – like Parkinsonism.
These food-drugs are certainly expensive – one estimate of coffee consumption puts it about $1100 per US adult, compared with about $1400 for commuting back and forth to work.
Yet overall, food-drug beverages appear to have stood the test of time. Many show positive dose response curves – the more drunk, the better the individual health effects.
They are also drunk socially – with that added benefit. And coffee houses and tea houses have traditionally been places where new social, political, and technological ideas have been hatched by well-caffeinated patrons talking and arguing together.
Stimulating indeed. And healthy.
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