Page 38 - BBC - The Scientific Guide to a Healthier You

COFFEE

There have been numerous claims over the years that
drinking coffee will increase your risk of succumbing to
a whole range of terrible things. Yet when scientists
followed over 120,000 men and women for more than 20
years they found something altogether more surprising.

The study, The Relationship of Coffee Consumption With
Mortality, concluded that “regular coffee consumption
was not associated with an increased mortality rate in
either men or women”. In fact, they found moderate
coffee consumption appears to be mildly protective.
Based on this and other studies, the most effective ‘dose’
seems to be two to five cups a day. More than that and
any benefits drop off. But we simply don’t know what
it is in coffee that helps.
The amount of coffee you can safely drink without side
effects, such as a temporary rise in blood pressure or
insomnia, may be down to your genes, and in particular
how much of the liver enzyme CYP1A2 you have. CYP1A2
helps determine the speed at which caffeine is cleared
from your body. This could explain why you can drink
coffee in the evening with no problems, while one cup
in the afternoon has your mate twitching.

VERDICT: Two to five cups of coffee a day are fine, but side
effects may be dictated by your genes.

38 BBC SCIENCE FOCUS MAGAZINE COLLECTION