A nutraceutical is a food or part of a
food that allegedly provides medicinal or health benefits, including the
prevention and treatment of disease. Grapefruit juice has been touted as
containing many compounds that can reduce hardening of the arteries (atherosclerosis)
and even the risk of cancer.
Grapefruit juice can, therefore, be justifiably referred to as a classic
nutraceutical. However, for many persons taking certain medications, grapefruit
juice might actually better be termed a "nutrapollutical!"
It turns out that grapefruit juice can
directly or indirectly interact in important ways with a number of medications.
This is especially important since grapefruit juice is consumed by
approximately one fifth of Americans for breakfast - a time of the day when
medications also are commonly taken.
Grapefruit juice blocks special enzymes
in the wall of the small intestine that actually destroys many medications and
prevents their absorption into the body. Thus, smaller amounts of the drugs get
into the body than are ingested. When the action of this enzyme is blocked,
more of the drugs get into the body and the blood levels of these medications
increase. This can lead to toxic side effects from the medications.
Amazingly, this remarkable food-drug
interaction was discovered completely by accident over a decade ago!
Researchers were investigating whether alcohol could interact with felodipine
(Plendil) and used a solution of alcohol with grapefruit juice to mask the
taste of alcohol for the study. Researchers discovered that blood levels of felodipine
were increased several fold more than in previous studies. This increased blood
level caused an increase in the effect and side effects of felodipine. Further
research revealed that the grapefruit juice itself was actually increasing the
amount of the study drug in the body.
Research about the interaction of
grapefruit juice with drugs suggests that compounds in grapefruit juice, called
furanocoumarins (for example, bergamottin), may be responsible for the effects
of grapefruit juice. Researchers believe that furanocoumarins block the enzymes
in the intestines that normally break down many drugs. One glass of grapefruit
juice could elicit the maximum blocking effect, and the effect may persist for
longer than 24 hours. Since the effects can last for such a prolonged period of
time, grapefruit juice does not have to be taken at the same time as the
medication in order for the interaction to occur. Therefore, unlike similar
interactions, where the interaction can be avoided by separating the administration
of the two interacting agents by a couple of hours, administration of
grapefruit juice with susceptible drugs should be separated by 24 or more hours
to avoid the interaction. Since this is not practical for individuals who are
taking a medication daily, they should not consume grapefruit juice when taking
medications that are affected by grapefruit juice.
The grapefruit juice-drug interaction can
lead to unpredictable and hazardous levels of certain important drugs.
by: Charlene Janice
KEEP ON A C T!
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