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From: sdyer@bbncc5.UUCP (Steve Dyer)
Newsgroups: net.med
Subject: Re: Tea
Message-ID: <66@bbncc5.UUCP>
Date: Fri, 22-Nov-85 01:23:19 EST
Article-I.D.: bbncc5.66
Posted: Fri Nov 22 01:23:19 1985
Date-Received: Sat, 23-Nov-85 10:52:11 EST
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Organization: Bolt Beranek and Newman, Cambridge, MA
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> 1) Does ordinary American tea-bag tea contain so little caffeine that it
> doesn't have much effect?

I bought a rather fascinating book last week called, not surprisingly,
"Caffeine", edited by Peter Dews, one of the first behavioral
pharmacologists.  One of the monographs in this collection defines the
"standard caffeine content value" of tea as 40mg/5 oz. cup for fresh-brewed
leaf or bag tea, and 30 mg/5 oz. cup for instant tea.  This single value
naturally can't accomodate the measured variability of tea's caffeine
content in studies--it's best to think of it as a modal value.  The actual
values range from 30-48mg, 28-44mg and 8-91mg in three different studies.
Compare these with the standard values for coffee: brewed, 85 mg./5oz.,
instant, 60 mg/5oz, and decaffeinated, 3 mg/5oz.  So, roughly, tea contains
half the caffeine of coffee.

> 2) Does iced tea impart much less caffeine to the body than hot tea will?
> (Assume the same brand tea, just temperature difference.)

Note that instant tea contains 25% less caffeine than brewed tea.  If your
iced tea is made using instant tea, this might help explain your
experience.  Tea is usually brewed using boiling water, and then either
served hot or cold.  One would expect identically prepared teas to contain
the same amounts of "biologically available" caffeine, regardless of their
serving temperatures.  I don't know about trying to brew tea using cooler
water.

> 3) Is there any truth to the idea of tea affecting vitamin potency or
> absorbtion? Which vitamins? What about affecting other food substances?

Teas contain tannins.  I've heard anecdotally that they can cause
constipation when consumed to excess (and we know from earlier articles
how dangerous THAT is :-)).  I know nothing about tea and vitamins.

-- 
/Steve Dyer
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