Study authors: Chun
Shing Kwok, S Matthijs Boekholdt, Marleen A H Lentjes, Yoon K Loke, Robert N
Luben, Jessica K Yeong, Nicholas J Wareham, Phyo K Myint, Kay-Tee Khaw.
Eating up to 100 g of chocolate every day is linked to lowered heart disease and stroke risk, finds research published online in the journal Heart.
There
doesn't seem to be any evidence for cutting out chocolate to lower the risk of
cardiovascular disease, conclude the researchers.
They
base their findings on almost 21,000 adults taking part in the EPIC-Norfolk
study, which is tracking the impact of diet on the long term health of 25,000
men and women in Norfolk, England, using food frequency and lifestyle
questionnaires.
The
researchers also carried out a systematic review of the available international
published evidence on the links between chocolate and cardiovascular disease,
involving almost 158,000 people--including the EPIC study participants.
The EPIC-Norfolk participants (9214 men and 11 737 women) were monitored for an average of almost 12 years, during which time 3013 (14%) people experienced either an episode of fatal or non-fatal coronary heart disease or stroke.
Around
one in five (20%) participants said they did not eat any chocolate, but among
the others, daily consumption averaged 7 g, with some eating up to 100 g.
Higher
levels of consumption were associated with younger age and lower weight (BMI),
waist: hip ratio, systolic blood pressure, inflammatory proteins, diabetes and
more regular physical activity --all of which add up to a favourable
cardiovascular disease risk profile.
Eating
more chocolate was also associated with higher energy intake and a diet
containing more fat and carbs and less protein and alcohol.
The
calculations showed that compared with those who ate no chocolate higher intake
was linked to an 11% lower risk of cardiovascular disease and a 25% lower risk
of associated death.
It
was also associated with a 9% lower risk of hospital admission or death as a
result of coronary heart disease, after taking account of dietary factors.
And
among the 16,000 people whose inflammatory protein (CRP) level had been
measured, those eating the most chocolate seemed to have an 18% lower risk than
those who ate the least.
The
highest chocolate intake was similarly associated with a 23% lower risk of
stroke, even after taking account of other potential risk factors.
Of
nine relevant studies included in the systematic review, five studies each
assessed coronary heart disease and stroke outcome, and they found a significantly
lower risk of both conditions associated with regular chocolate consumption.
And
it was linked to a 25% lower risk of any episode of cardiovascular disease and
a 45% lower risk of associated death.
This
is an observational study so no definitive conclusions about cause and effect
can be drawn. And the researchers point out that food frequency questionnaires
do involve a certain amount of recall bias and underestimation of items eaten.
Reverse
causation--whereby those with a higher cardiovascular disease risk profile eat
less chocolate and foods containing it than those who are healthier--may also
help to explain the results, they say.
Nevertheless,
they add: "Cumulative evidence suggests that higher chocolate intake is
associated with a lower risk of future cardiovascular events."
And
they point out that as milk chocolate, which is considered to be less 'healthy'
than dark chocolate, was more frequently eaten by the EPIC-Norfolk
participants, the beneficial health effects may extend to this type of
chocolate too.
"This
may indicate that not only flavonoids, but also other compounds, possibly
related to milk constituents, such as calcium and fatty acids, may provide an
explanation for the observed association," they suggest.
And
they conclude: "There does not appear to be any evidence to say that
chocolate should be avoided in those who are concerned about cardiovascular
risk."