| Evidence of How Food
Might Shift Body Clock
NEW YORK (Reuters
Health) - The body has an internal clock
that affects vital signs such as temperature and blood pressure
and also influences when we sleep and wake.
While many experts argue that light
has the strongest influence on how that clock is oriented, some
evidence suggests that what and when we eat might p]lay an equally,
if not more important, role. Now, new study findings by Dr. Steven
McKnight of the University of Texas Southwest Medical Center in
Dallas and colleagues provide further evidence that food has a
significant effect on our internal clock, or circadian rhythm.
Regardless of whether food or light
has the upper hand, more and more evidence suggests that people
who travel to a new time zone should adopt the meal schedule of
the new place to help combat jet lag, McKnight told Reuters Health.
If an airline offers a large meal
that matches the place you just left but not where you are going,
the researcher suggested opting out, and trying to train your
stomach to adopt to your destination's time zone. "Begin to have
your feeding cycle on that new daylight schedule that you're going
to be in," McKnight advised.
Previous experiments have shown that
mice, which normally sleep during the day, can be taught to reverse
their schedule if they are only fed during daylight hours. Genetic
analyzes of these altered mice reveal that genes that were turned
on when the mice slept during the day were now turned off--and
vice versa--indicating that their body had undergone internal
changes to adapt to the shift in schedule.
Recently, McKnight and his team discovered
more details on how food can influence circadian rhythms. Food
contributes a certain amount of fuel for the body processes, which
gets stored in the form of a substance known as NADPH. When that
fuel is used up, it becomes converted into NADP.
The researchers demonstrated that
the Clock gene transcription factor, which controls how our body
clock is set at certain times, may sense how much NADP is present
in relation to the amounts of NADPH and act accordingly. In humans,
for instance, in the morning the body contains little NADPH relative
to NADP, since the night is spent using up fuel rather than adding
it via meals. This particular ratio of NADP to NADPH may tell
the transcription factor to behave in a certain fashion--in humans,
it helps tell the body clock it is time to wake up.
Now, McKnight and his team discovered
new findings that help link circadian rhythms to metabolism, which
he presented Sunday at the Society for Neuroscience's annual meeting
in Orlando, Florida.
At the meeting, McKnight demonstrated
that mice that lack the Clock gene transcription factor are unable
to switch to sleeping during the night when they are only fed
during daylight hours. Mice tend to spend many of their waking
hours running on a wheel, and those that lack this body clock
regulator also are unable to take naps between their normal waves
of activity, a characteristic habit in mice.
All in all, McKnight said he believes
that all of the previous evidence demonstrates that food has a
stronger influence on circadian rhythms than light. "When you
ask whether food or light wins, food wins," he told Reuters Health.
Reference Source 89