| A little of what you fancy does you good: or great news about chocolate |
| John Livesey PhD Scientific Officer Department of Endocrinology Christchurch Hospital New Zealand |
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Chocolate
is not only delicious but now seems to be good for you, in fact very
good for you. Long regarded as seductive but highly calorific and
guilt-inducing junk-food, chocolate in fact appears to have
remarkable health benefits according to recently published Dutch
research1. Four hundred and seventy healthy elderly men
living in Zutphen were studied in 1985 and again in 1990 and 1995 to
examine the relationship between their diet and their health. Their
average age at the start of the study was 72 and by the year 2000 67%
of them had died. From the men's food diaries the researchers
calculated their cocoa intake (from all cocoa-containing foods) and
noted what these foods were. One third did not eat any
cocoa-containing food, the intake of the middle third was 0.9 grams
of cocoa per day on average and the third who consumed the largest
amounts of cocoa had an average intake of 4.2 grams of cocoa per day.
The
most remarkable finding of the study was that the one third of men
who consuming the largest amounts of cocoa had a 45 to 50% lower
death rate than did the one third who consumed no cocoa. Going along
with this, the high cocoa group was also found to have a similarly
marked reduction in their death rates from heart disease.
Remarkably,
this dramatic reduction in the death rate was seen despite the large
majority of the cocoa being eaten in the form of foods high in
saturated fat and sugar. More than half of the cocoa consumed was as
plain or nut chocolate (28% dark, 22% milk, 3% with nuts) with
significant contributions from chocolate confetti sandwich filling
(15%), chocolate candy bars such as Bounty Bars and Mars Bars (10%)
and boxed chocolates (2%). Of lower fat foods, desserts contributed
5% and cocoa drinks 4% . Only 6% was consumed as cocoa itself.
A
further pleasantly surprising feature of the research findings was
just how little chocolate was needed to obtain this major reduction
in mortality. The four grams or so of cocoa consumed per day by the
top third of the men is equivalent to about 13 grams of a dark
chocolate containing about 47-48% cocoa solids (for example Whittaker's
Dark Block, Trade Aid Dark Chocolate*) or to about 6 grams of a chocolate containing 70%
or more cocoa solids (Whittaker's Dark Ghana or Lindt
Excellence Dark 85% Cocoa). In other words, it amounts to
about one or two squares, maybe three, of typical chocolate blocks.
Were
the high chocolate consumers heavier? Again the answer is a welcome
surprise. They were in fact just a little lighter, the top third of
consumers having a body mass index (BMI) of 25.3 whereas the third
who never touched cocoa-containing products had a BMI of 25.9. This
was despite the high consumers eating in total more calories per day
(2400 compared to 2100) while apparently not exercising more, raising
the possibility that modest amounts of cocoa increase the basal
metabolic rate.
The
beneficial effects of eating all this cocoa-containing confectionery
did seem to be specifically due to the cocoa content since the level
of consumption of sugar confectionery in general was not found to be
related to cardiovascular mortality. Since
it was discovered in 1996 that chocolate contained phenolic compounds
variously known as polyphenols, flavanols or catechins, there has
been considerable interest in its possible health benefits. Chocolate
and cocoa have been shown to lower blood pressure (as was also found
in the study described above), to improve the efficiency of insulin
action and to have anti-inflammatory properties2. Recently it has
been reported that the consumption of a cocoa drink for twelve weeks
significantly decreases the amount of damage done to human skin by
ultraviolet light3. Chocolate
is principally composed of cocoa, cocoa butter and sugar. The first
two both come from the cocoa bean, the cocoa butter being the fatty
portion and the cocoa the non-fat portion. Because the polyphenols
are water soluble it is generally assumed that most of the health
benefit comes from the cocoa part whereas the cocoa butter
contributes only calories and saturated fat, both probably relatively
undesirable. Assuming this is true, to maximise the health benefits
of chocolate while minimising the number of calories consumed it is
preferable to eat chocolate that contains a high proportion of cocoa.
The better manufacturers state on their labels the percentage of
cocoa solids in their chocolate, for example 48% for Trade Aid's Dark
Chocolate* and 85% for Lindt Excellence Dark 85% Cocoa. This
figure however includes both the cocoa and the cocoa butter fractions
and so does not give the actual proportion of cocoa in the chocolate.
However higher percentages of cocoa mass will usually indicate a
higher proportion of cocoa.
Another
way to compare chocolate bars for cocoa content is to use the
proportion of protein per 100 grams (this is stated on the
nutritional information label). As neither cocoa butter nor sugar
contain protein but cocoa itself is about 19% protein, the more
protein in a chocolate bar the more cocoa there is likely to be.
Different cocoas and chocolate can vary in polyphenol content too,
but this information is not readily available to the consumer except
insofar as since polyphenols taste bitter, the more bitter the
chocolate is, the more polyphenols it probably contains. Anyone
concerned though about their caloric intake might instead wonder whether they could get their
polyphenols from cocoa powder, which has a much lower fat and sugar content than chocolate.
Unfortunately, getting your polyphenols from a nice cup of hot cocoa is complicated by the fact that
most cocoa powder sold in New Zealand is treated with alkali (so called "Dutching") to make it less acidic,
to darken it
and to give it a more chocolatey flavour. The problem with Dutching is that it destroys most of the
polyphenols in the cocoa. Cadbury's, Pam's, Valrhona and Camino cocoa are all Dutched, tho' Camino
is less so than the other three. The only reliable sources of natural cocoa I have found so far in New Zealand
are wholesalers. Chantal sell Fair Trade organic natural cocoa and
Hawkins Watts sell ADM natural cocoa.
In
summary, two squares per day of dark chocolate, the darker the
better, may very well improve your health as well as being a
delicious treat. And the number of calories in two squares of dark
chocolate is not large either, only about 60 calories in the case of
Whittakers Dark Ghana for example, or around 3% of daily
calories. Or have a cup of natural cocoa daily
Note: all products named are vegan (apart from Bounty Bars and Mars Bars); those marked * are Fairtrade References
Buijsse Bet al. Archives of Internal Medicine 166:411
(2006).
Di Giuseppe R et al. Journal of Nutrition 138:1939-45 (2008).
Heinrich U et al. Journal of Nutrition 136:1565-9 (2006).
Porphyry's People home page.
NZT: 23/Oct/08 21:17:32. GMT: 23/Oct/08 08:17:32.