Evidence of How Food Might Shift Body Clock

55 minutes ago

By Alison McCook

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
play 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.