Blood pressure lowering effects
A large-scale, longer duration study in the Netherlands
recruited men aged 65-84 years. The subjects were asked
about their dietary intake when they enrolled in the study
and again at five-year intervals. Over the next 15 years, men
who consumed cocoa regularly had significantly lower
blood pressure than those who did not. Consumption of
dark chocolate bars for 15 days has been reported to reduce
systolic blood pressure in healthy subjects28 as well as in
young and elderly hypertensive patients.
The exact mechanism behind antihypertensive effects
of chocolate is not known but this may involve increased
nitric oxide (NO) bioavailability, flavonol-induced inhibition
of angiotensin converting enzyme, and stearic acid-based
reduction of diastolic blood pressure.
Contrary to that, a few studies showed no effect on blood
pressure with chocolate/cocoa ingestion., Van den
Bogaard et al. in fact put in question the blood pressure
lowering effects of cocoa. They concluded from their
randomised controlled trial that natural cocoa drinks
did not significantly change either 24-hour ambulatory
or central systolic blood pressure.Alonso also found no
association between chocolate consumption and incidence
of hypertension in a Cohort study. The reason for
these inconsistencies may relate to a number of factors,
including the study design. Since these studies were
performed in a rather small number of normotensive
individuals and with a lower chocolate intake for a shorter
period, an antihypertensive effect may have been missed
as a consequence of their study design. Moreover, use
of different dietary intake questionnaires and food
consumption tables, differences in the levels and the
types of chocolates/cocoa studied and differences in
the populations investigated, might also account for
inconsistencies. Most of the studies supporting
antihypertensive effects of chocolate used chocolate bars,
whereas the negative studies used cocoa drinks. Perhaps
the chocolate matrix is necessary for the antihypertensive
effect, acting either directly or synergistically with
flavonols