Caffeine reaches its maximum levels in the
blood between 15 minutes and two hours after
consumption, and its levels are reduced by
half within three to seven hours. Its effects are
more noticeable in people who don’t normally
consume it. Withdrawal symptoms can be
unpleasant, but usually disappear within three
days of abstaining.
A chemical relative of caffeine called
theophylline is found in tea and is in some
respects more potent than caffeine, but tea
contains only trace amounts. Though coffee
beans are 1–2% caffeine and tea leaves 2–3%,
brewed coffee contains more caffeine than
brewed tea because a larger weight of coffee
is extracted per cup (8–10 grams, vs. 2–5
grams for tea).
Tea, Coffee, and Health
Not so many years ago, both coffee and tea
were suspected of contributing to various