Encyclopedia of Health and Medicine

milk thistle 89
Raising the level of melatonin in the bloodstream
increases drowsiness, which has led to the
use of melatonin supplement as a sleep aid. In the
United States melatonin is available as an overthe-counter
dietary supplement. In most European
countries, however, melatonin is available
only with a doctor’s prescription. This is because
researchers do not fully understand the functions
of melatonin in the body though they do know
that as a hormone, melatonin has numerous
effects within the body in addition to the roles it
plays in sleep cycles and the circadian rhythm.
Some studies have found that melatonin causes
blood vessels to constrict, perhaps by stimulating
the release of CORTISOL, raising blood pressure.
Though this finding is not conclusive, health
experts advise people who have HYPERTENSION (as
well as people who have other forms of CARDIOVAS-
CULAR DISEASE (CVD), DIABETES, and KIDNEY disease)
not to take melatonin to avoid this risk.
A number of studies support melatonin’s ability
to relieve jet lag and help people adjust to sleeping
during the day when they work during the night.
However, there are no studies that conclusively
identify supplemental melatonin’s benefits or
risks. Melatonin interacts with numerous prescription
medications and should be taken only after a
doctor’s examination determines there are no
neurologic or other physiologic causes for insomnia.
Even people taking melatonin for jet lag or to
restructure their sleep patterns to accommodate
shift work should first consult with their doctors
to make sure they have no health conditions that
make it unsafe for them to take melatonin supplements.
Melatonin causes drowsiness within 20 to 30
minutes of taking a DOSE, an effect that lasts four to
six hours. Some people experience a “hangover”
effect when they wake up, feeling groggy and disoriented
for as long as several hours. People must
not drive or operate machinery after taking a melatonin
dose, as the onset of sleepiness can be sudden
and irresistible. Some people also experience
increased insomnia or have vivid dreams and
nightmares as well as fatigue after taking melatonin.
Melatonin taken in combination with other
medications that cause drowsiness can result in an
intensified effect (excessive sleepiness).
MELATONIN
Uses Risks/Side Effects Interactions
sleep aid drowsiness CORTICOSTEROID MEDICATIONS
possible fertility prescription sleep aids
problems
ASTHMA medications
may elevate BLOOD ANTIHISTAMINE MEDICATIONS
PRESSURE
narcotic ANALGESIC
insomnia
MEDICATIONS
fatigue
ANTIANXIETY MEDICATIONS
MUSCLE RELAXANT
MEDICATIONS
ANTIDEPRESSANT MEDICATIONS
See also ANTI-AGING APPROACHES; SLEEP DISORDERS;
VALERIAN.
milk thistle A medicinal herb, also called holy
thistle, that helps protect the LIVER from INFECTION
and improves the liver’s ability to regenerate from
damage. Numerous clinical studies support this
benefit. The active ingredient in milk thistle is silymarin,
a composite of five flavonoids (siliandrin,
silibinin, silydianin, silymonin, and silychristin),
which is in highest concentrations in the milk
thistle seeds. Silymarin strengthens the structure
of hepatocytes, the cells in the liver that metabolize
toxins. It may also influence aminotransferases,
the enzymes the liver produces to break
down chemical substances the liver extracts from
the blood.
Doctors often recommend milk thistle for people
who have LIVER DISEASE OF ALCOHOLISM, CIRRHO-
SIS, or chronic HEPATITIS, or who have ingested
toxic mushrooms or toxic doses of medications
such as acetaminophen. Some people who have
HIV/AIDS take milk thistle or silymarin extract to
protect their livers from the potentially damaging
effects of some of the medications used to treat
HIV/AIDS. There also is limited evidence that milk
thistle has a similarly protective function in the
kidneys though researchers continue to explore
this possible effect. A folk medicine use for milk
thistle, likely the origin of the plant’s name, is to
stimulate BREAST milk production in nursing mothers.
Of the few studies that have investigated this
use, there have been no conclusive findings about
benefits or risks. Because the effects are unknown,