Are
food
cravings
the body's way of telling us that we are lacking certain
nutrients?
Food craving, defined as an intense
desire to eat a specific foodstuff, is a common occurrence across all
cultures
and societies. These yearnings are apparently not linked to any obvious
nutrient insufficiency.
A number of
mechanisms have been
advanced to explain the physiological and pathological changes in
behavior that
lead to food cravings and a loss of control of over eating. The latter,
of
course, is a major concern with obesity
and a number of eating disorders.
Researchers have
employed functional
magnetic
resonance imaging (fMRI) to explore the basis of cravings in the brain
and the
imaging data suggest that components of the amygdala, anterior
cingulate,
orbital frontal cortex, insula, hippocampus, caudate and dorsolateral
prefrontal cortex are activated during periods of pining for food. It
appears
that there may be a network of brain regions that is involved with the
emotion, memory and chemosensory stimuli of food craving.
Eating is generally
a pleasurable
social experience. Using chocolate consumption as an example, it
follows that
there may be constituents in chocolate that influence feeling satisfied
or
alter our
acceptance of the treat, including psychoactive or mood-altering
compounds such as phenylethylamine, tyramine, serotonin, tryptophan and
magnesium. It is important to note, however, that many other foods,
including
dairy products, also contain these compounds at higher concentrations
but tend
to have somewhat lesser appeal than chocolate does.
Studies suggest
that chocolate
craving, especially among women, may result from a sense of deprivation
or in
reaction to stress, menstrual hormonal fluctuation and alteration of
neuropeptide
concentrations.
Regardless of the
factor(s) that initiate chocolate
cravings in
women, the apparent physical explanations are inconsistently
expressed in
a diversity of cultures, especially among those that consume large
amounts of
chocolate. Spanish women, for example, eat relatively large quantities
of
chocolate and exhibit limited chocolate craving. This is in contrast to
many
American women who consume relatively little chocolate yet present a
strong
chocolate craving. Clearly, the relationship between food preferences,
mood and
the menstrual cycle is complex.
Some investigators
have proposed
that carbohydrate craving (with resulting consumption) increases
depression.
This theory results from some observations that diet can modulate the
serotonergic system in the brain, which is linked to mood. Research
that shows
administration of naloxone, an opiate antagonist, appears to reduce
food intake
provides additional evidence for a nutrition-neurological interaction.
This
effect appears to inhibit mainly the consumption of sweet, high-fat
foods such
as chocolate. Studies of cannabinoids and antagonism of cannabinoid
receptors
have shed more light on the complex neurochemistry of selective
appetite. In
addition, research on satisfaction or appetite control mechanisms
in the
gastrointestinal tract has led to the identification of an entire
spectrum of gut
neuropeptides with elaborate central nervous system feedback.
"Cravings"
undoubtedly represent a true bio-psycho-social paradigm in which
sociocultural
factors, stressful environments and hormonal fluctuation participate in
a
complex drama performed on a neurological stage and the result has
varied--and
as yet incompletely understood--implications for nutrition and health.
