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Chocolate: The Latest Health Food?
In a recent Dutch study, researchers compared the levels of antioxidant
catechins in chocolate (Theobroma cacao L., Sterculiaceae
) and black tea (Camellia sinensis [L.] Kuntze,Theaceae).
Catechins (a type of flavonoid or polyphenol) are commonly associated
with tea, but are also found in red wine and a variety of other
foods. Based on research with green tea, scientists believe that
these compounds may play an important role in protecting against
heart disease, cancer, and other health conditions. In this study,
a team of researchers analyzed levels of six major catechins in
dark chocolate, milk chocolate, and freshly brewed black tea (Arts
et al., 1999). They found the highest level of total catechins
in dark chocolate (53.5 mg per 100 g). Levels were much lower
in milk chocolate (15.9 mg of catechins per 100 g) and black tea
(13.9 mg per 100 ml). Based on these results, the Dutch team declared,
"the antioxidant catechin content of chocolate is four times
that of [black] tea."
In the second part of the study, researchers evaluated the importance
of chocolate as a source of catechins in the Dutch diet. The survey,
which drew from a sample of 6250 people, aged one to 97 years,
revealed that black tea was the most important source of catechins
(55 percent of total intake) and that chocolate contributed an
additional 20 percent of catechins. The authors pointed out that
chocolate might contribute an even larger percentage of catechins
in younger age groups who drink less tea. They concluded with
the statement that "epidemiological studies on the health
effects of catechins in tea will give biased results if other
catechin-rich foods such as chocolate are ignored."
There is still much that is unknown about catechins in various
foods. Researchers have conducted a considerable amount of research
on green tea, with some studies indicating that between four and
five cups of green tea a day (approximately 1600 mg of polyphenols)
are needed to provide therapeutic effects. The equivalent amount
of catechins needed from black tea and chocolate to provide a
similar effect is unknown. However, another recent study also
reviewed in this issue (Geleijnse et al., 1999) suggests
that black tea in the Dutch diet does provide significant health
benefits, although it does not allow for the effects of chocolate.
See the review entitled "Black tea may protect heart health"
for details about this study.
In addition, the researchers pointed out that chocolate and black
tea contain different types of catechins. Chocolate contains (+)-catechin
and (-)-epicatechin, while black tea contains higher amounts of
(-)-epicatechin gallate and (-)-epigallocatechin gallate, with
low concentrations of (+)-catechin, (-)-epicatechin, (-)-epigallocatechin,
and (+)-gallocatechin. Researchers still don't know precisely
how these catechins differ in terms of health benefits. Clearly,
more research is needed before we can elevate chocolate to "health
food" status. - Krista
Morien, HRF
[Arts ICW, Hollman PCH, Kromhout D. Chocolate as a source of
tea flavonoids. The Lancet (Research Letters) 1999; 354:
488.
Geleijnse JM, Launer LJ, Hofman A, Huibert APP, Witteman JCM.
Tea flavonoids may protect against atherosclerosis. The Rotterdam
Study. Archives of Internal Medicine 1999; 159: 2170-2174.]
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