If you’ve had a heart attack, a bar of chocolate is probably the last thing
your doctor would recommend. Nevertheless, new evidence suggests that
chocolate could save your life by reducing your risk of having a fatal heart
attack in the future.
Swedish researchers, as part of the Stockholm Heart Epidemiology Program
(SHEEP), quizzed 1169 heart-attack survivors on their chocolate consumption,
then followed them for eight years to see how their health fared. They found
that the more chocolate was eaten, the lower the risk of death due to heart
disease-even after taking into account other risk factors such as obesity,
smoking and alcohol consumption.
Those who regularly indulged in chocolate-two or more times per week-were up
to three times less likely to die of heart problems than those who avoided
it. Even eating chocolate less that once a month had a significant
protective effect (J Intern Med, 2009; 266: 248-57).
These findings are intriguing, but not surprising. Recently, the evidence
has been stacking up that chocolate-far from being an unhealthy treat-is
actually a functional food with cardioprotective properties. But beware: not
all chocolate is created equal. Although the Swedish study didn’t
distinguish between types of chocolate, much of the research indicates that
it’s only the dark kind that’s good for the heart.
In one study, dark-but not white-chocolate was found to dramatically reduce
blood pressure (BP) in 20 mildly hypertensive patients, who were randomly
assigned to receive either 100 g of dark chocolate or 90 g of white
chocolate every day for two weeks. Only the dark chocolate had beneficial
effects, causing systolic BP to plummet by an average of 11.9 mmHg, and
diastolic BP by 8.5 mmHg. This means that chocolate is as effective as many
of the antihypertensive drugs currently on the market (Hypertension, 2005;
46: 398-405).
When doctors at the University of Cologne in Germany ran a similar study,
but with less chocolate (just 6.3 g/day, equal to 30 calories), remarkably,
even this small amount of dark chocolate (but, again, not white chocolate)
was able to reduce BP by almost 3 mmHg. Although small, such a decrease
applied across a population “would reduce the relative risk of stroke
mortality by 8 per cent, of coronary artery disease mortality by 5 per cent,
and of all-cause mortality by 4 per cent”, the researchers estimated (JAMA,
2007; 298: 49-60).
This suggests that we can enjoy the benefits of chocolate without piling on
the pounds.
A guilt-free pleasure
In addition to lowering BP, dark chocolate appears to increase ‘good’ HDL
cholesterol while lowering ‘bad’ LDL cholesterol (Free Radic Biol Med, 2004;
37: 1351-9; J Nutr, 2008; 138: 1671-6). It’s also been shown to reduce
platelet clumping (blood clots) and to improve function of the endothelium,
the inner lining of the arteries responsible for producing nitric oxide,
which dilates blood vessels and keeps the vessel lumen clear of obstructions
(Circulation, 2007; 116: 2376-82; J Am Coll Nutr, 2004; 23: 197-204).
But how is it that such a high-fat, sugar-laden treat can be good for us?
The dark chocolate bars used in most studies were at least 70-per-cent cocoa
solids. Although these bars typically include around 12 g of sugar, the
cocoa packs such a healthy punch that it counteracts any adverse effects of
the sugar. The key ingredients in cocoa are the flavanols, a subgroup of the
natural antioxidant plant compounds called ‘flavonoids’, already well-known
for their heart-healthy effects (Nutr Today, 2002; 37: 103-9). Indeed, the
Kuna Indians of Panama, who regularly consume large amounts of flavanol-rich
cocoa, are virtually free of hypertension and stroke, even though they add
salt to their food (Med Hypotheses, 2009 Jul 2; Epub ahead of print).
As for the fat in chocolate, much of it is present in the form of stearic
triglycerides, which increase good HDL cholesterol and are readily cleared
from the body via the gut (Crit Care Nurse, 2007; 27: 11-5). Also, the fat
slows the rate at which the sugar is released into the bloodstream, making
dark chocolate a low glycaemic index (GI) food.
So, while it may be some time before doctors start recommending a bar of
chocolate a day, it certainly seems that the old adage is true: a little of
what you fancy does you good.
Joanna Evans
Beyond heart health
Besides heart disease, chocolate may also have a role to play in other
health problems.
– Sun damage. Eating chocolate rich in flavanols can help to protect
the skin from harmful ultraviolet (UV) radiation. When 30 volunteers were
given 20 g/day of either high- (HF) or low- (LF) flavanol chocolate daily,
after 12 weeks, those in the HF group saw their minimum erythema dose-the
minimum dose of UV light to cause skin redness-more than double, while
no significant changes were seen in the LF group (J Cosmet
Dermatol, 2009; 8: 169-73).
– Diabetes. Dark chocolate may help to prevent diabetes. Eating 100
g/day of dark, but not white, chocolate for two weeks improved insulin
sensitivity (which leads to diabetes) in healthy volunteers (Am J Clin Nutr,
2005; 81: 611-4).
– Chronic fatigue syndrome (CFS). In a placebo-controlled study of 10
patients with CFS, eating 15 g of dark chocolate three times a day
significantly improved fatigue and physical functioning over an eight-week
period. Indeed, two patients were able to return to work after having
suffered CFS symptoms for two years (Endocrine Abstracts, 2006; 12: 68).
Vol. 20 08 November 2009
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