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Transcript
The Psychology of Chocolate
Key Points
•
•
Chocolate is made from the seeds of the tropical cacao tree
Research suggests chocolate may have
health benefits
Chocolate cravings may be a symptom of addiction
•
Chocolate contains the same
'happy' chemicals found in some recreational drugs
Chocolate history
•
Chocolate is made from the seeds of the tree
Theobroma cacao.
•
Theobroma is Greek for 'food of the gods'.
History
•
•
The ancient Aztecs venerated the cacao tree
and used its beans as a form of currency.
They saw the tree as a source of strength
and wealth and assigned their god
Quetzalcoatl its guardian.
History
•
•
The Aztecs discovered that by crushing the
beans into a paste and adding spices, they
could make a refreshing and nourishing
drink.
This drink would have been very bitter,
unlike our chocolate drinks today.
History
•
16th century European explorers brought
the drink back from their travels, added
sweeter flavorings, and soon it was popular
as an expensive luxury.
Making Chocolate
The First Chocolate Bars
•
In the 1800s, solid chocolate became
popular, with the invention of molding
processes. Mechanical grinders crushed
cocoa beans to a fine powder that could be
heated and poured into moulds, forming
shapes as it cooled.
The First Chocolate Bars
•
Dutchman Coenrad Van Houten
perfected the extraction of cocoa butter
from cocoa beans in 1825. The beans are
crushed to a paste, which is subjected to
very high pressure, forming chocolate
liquor and cocoa butter. The extracted
butter is smoothed and treated to remove
any odours.
The First Chocolate Bars
•
In the 1880s, Rudolphe Lindt of
Switzerland started adding extra cocoa
butter during chocolate manufacture, to
make it smoother and glossier. Cocoa
butter melts at around 97°F, which is
human body temperature. That's why
chocolate melts in the mouth.
Milk chocolate
•
In 1875, Swiss Daniel Peter perfected the
manufacture of milk chocolate, which is
sweeter and smoother than dark chocolate.
Nestlé's recently-invented condensed milk
was easy to mix with cocoa paste, unlike
liquid milk.
Milk chocolate
•
Cadbury's 'Dairy Milk', first developed
in 1905, is the UK's most popular
chocolate bar. Milk chocolate is now the
world's best-selling variety.
Chocolate craving
•
The love of chocolate goes beyond the call
of sweetness. Chocolate can induce
craving in a way that other sugary
products like toffee or marshmallow
don't. Chocolate makes us feel good, but
can it really be addictive?
Chocolate craving
•
All modern commercial chocolate
products contain substantial amounts of
sugar, a fact which may partly explain
chocolate's supposed addictive
properties.
Chocolate Craving
•
•
•
Chocolate has a number of drug like effects.
It has caffeine, although less than coffee,
and theobromine, that is a neurostimulator
that produces pleasure.
The best chocolate for these effects is dark
chocolate.
Chocolate Craving
•
•
Dark chocolate has a stronger more intense
chocolate flavor and a hint of bitterness.
It is the bitterness that is associated with
some of the good things.
Sweet tooth
•
You can inherit a 'sweet tooth' from your
parents. Recent research at New York
University suggests there is a genetic reason
why some people crave sugary foods.
Sweet tooth
•
The study was based on two strains of
mice, selectively bred according to
whether the parents preferred sweetened
or unsweetened water. The team located
the gene that was different in the two
groups of mice and then searched for
similar genetic sequences in humans.
Sweet Tooth
•
•
An ability to identify sweet things, and a tendency
to respond to them positively, would have been an
advantage for our ancestors.
Such a genetic trait would have made prehistoric
humans seek energy-rich, highly nutritional food
such as fruit, while avoiding bitter-tasting
poisonous plant material.
Sweet Tooth
•
This ancient genetic preference is arguably
less useful in the context of a modern
supermarket.
Chocolate chemistry
•
Like other sweet food, chocolate stimulates
the release of endorphins, natural body
hormones that generate feelings of pleasure
and well-being.
Chocolate Chemistry
•
General sweetness aside, there are
various chemical elements specific to
chocolate that may help to stimulate
cravings. In fact, chocolate contains over
300 chemicals and it is not known how all
of these affect humans.
Chocolate Chemistry
•
Many women report particular chocolate
cravings when pre-menstrual. This is
possibly because chocolate contains
magnesium, a shortage of which can
exacerbate pre-menstrual tension.
Similar cravings during pregnancy could
indicate mild anaemia, which chocolate's
iron content may help to cure.
Chocolate Chemistry
•
•
Chocolate contains magnesium and iron,
which may be part of why women, who
need more of these nutrients, crave
chocolate.
Magnesium deficiencies contribute to premenstrual tension.
Chocolate Chemistry
•
Central nervous stimulants such as
caffeine are also present in small
amounts, and this has a mild effect on
alertness as we know from drinking
coffee.
Chocolate Chemistry
•
Chocolate also makes us feel good by
reacting with our brains.
Chocolate Chemistry
•
Another mild stimulant present in
chocolate is theobromine, which also
serves to relax the smooth muscles in the
linings of the lung.
Why Chocolate Makes Us Feel
Good
•
•
Several more obscure chocolate
ingredients seem to act by affecting the
brain's own neurotransmitter network.
Neurotransmitters are the chemical
messengers of the brain. They work by
transporting electrical signals between
nerve cells. These signals cause changes
in the sensations and emotions that we
experience.
Love drug?
•
Chocolate contains a natural 'love drug'.
Tryptophan is a chemical that the brain uses
to make a neurotransmitter called
serotonin..
Love Drug?
•
High levels of serotonin can produce
feelings of elation, even ecstasy - hence the
name of the designer drug that also works
by increasing serotonin levels
Lust drug?
•
While tryptophan could be considered
'chocolate's ecstasy', another chemical
called phenylethylamine has earned the
nickname 'chocolate amphetamine.'
Lust Drug?
High levels of this neurotransmitter help
promote feelings of attraction, excitement,
giddiness and apprehension.
Phenylethylamine works by stimulating the
brain's pleasure centers and reaches peak
levels during orgasm.
Lust Drug?
•
But many scientists are skeptical that
chocolate could produce mood-altering
effects in this way. Chemicals like
tryptophan and phenylethylamine, which
are also found in many other foodstuffs,
are present in chocolate only in very
small quantities.
Chocolate Pot?
•
The same is true of anandamide, the current
favourite candidate for a psychoactive chocolate
ingredient. Anandamide is a neurotransmitter that
targets the same brain structures as THC, the
active ingredient in cannabis. But to make a
substantial impact on the brain's own natural
anandamide levels, experts estimate you would
need to eat several kilos of chocolate!
Chocolate Pot?
•
Neuroscientist Daniele Piomelli suggests that
chocolate works more indirectly to produce its
'high'. As well as anandamide itself, chocolate
contains two chemicals known to slow the
breakdown of anandamide. Chocolate might
therefore work by prolonging the action of this
natural stimulant in the brain. The animation
below shows how this could work.
Chocoholism
•
This type of effect is a possible scenario for
the development of a physical dependency
on chocolate. Current studies of
psychoactive drugs show that addiction is
associated with the formation and
reinforcement of unusual neurotransmitter
pathways in the brain.
Chocoholsim
•
•
So it's just possible that, with every
binge, your brain is being gradually
'rewired' in order to make you love
chocolate more and more!
But could chocolate be good for you?
Is Chocolate Good For You?
•
Should chocolate be an essential
component of a balanced diet? Back in
the 17th and 18th centuries, many
treatises were written extolling the
medicinal virtues of chocolate and today
it's a regular feature in army food
rations.
Is Chocolate Good For You?
•
During the Gulf War, critical equipment
flown out to US forces included a
specially formulated heat-stable
chocolate bar. But the jury is still out on
whether or not it's good for us.
Chocolate toothpaste
•
Chocolate could help prevent tooth decay,
according to scientists at Japan's Osaka
University. The husks of the cocoa beans
from which chocolate is made contain an
antibacterial agent that fights plaque. These
husks are usually discarded in chocolate
production, but in future they could be
added back in to chocolate to make it
dental-friendly.
Chocolate toothpaste
•
They concluded that the cavity-fighting
action of cocoa bean husks isn't enough
to offset decay caused by chocolate's high
sugar content, however, so chocolate isn't
going to replace toothpaste any time
soon.
Hearty findings
•
Californian scientist Professor Carl Keen
and his team have suggested that chocolate
might help fight heart disease. They say that
it contains chemicals called flavinoids,
which thin the blood, helping to prevent
clotting.
Hearty findings
•
Scientists have already suggested that red
wine acts in this way. However, sceptics
have pointed out that Keen's research is
funded by confectionery maker Mars.
Good news and bad news
•
Researchers at Harvard University have
carried out experiments that suggest that if
you eat chocolate three times a month you
will live almost a year longer than those
who forego such sweet temptation.
Good news and bad news
•
But it's not all good news - the Harvard
research also suggested that people who
eat too much chocolate have a lower life
expectancy. Chocolate's high fat content
means that excess indulgence can
contribute to obesity, leading to an
increased risk of heart disease.
Good news and bad news
•
It looks like the old adage of "everything
in moderation" holds. But if you can't
resist chocolate, at least stick to dark. It's
higher in cocoa than milk chocolate and
helps to increase levels of HDL, a type of
cholesterol that helps prevent fat clogging
up arteries.
Death by chocolate
•
Dogs and other domestic animals like
horses metabolise the chocolate ingredient
theobromine more slowly than humans.
Safe doses for us could be toxic or even
lethal doses for our pets, affecting their
hearts, kidneys and central nervous systems.