Optimum Nutrition - Spring 2020 PREVIEW

FEATURE
W
hen our ancestors discovered
fire, did teen cave people refuse
to go to their animal skin blanket
and adults start staying up late just to
binge watch pictures in the flames?
Maybe not, but as a species we do tend to
fight with Mother Nature.
Yet increasingly, research indicates that
although we can take the person out of
the cave, we can’t take the cave out of
the person. Even for so-called ‘night owls’
there is an inner early human in all of us
with a biological clock that is hard-wired
to the rhythms of the day. One study
looking at neural signatures of sleep has
hypothesised that they may have evolved
at least 450 million years ago, long before
our ancestors crawled out of the ocean. 1
And it appears that going against this
biological clock could be fuelling much of
the health problems that we see today.
This may be hard to swallow, especially
for those who happily follow irregular
bedtimes or mealtimes. Yet increasingly,
experts warn that ignoring our circadian
rhythms may contribute to a range of
diseases such as obesity, type 2 diabetes,
fatty liver disease, depression, anxiety, and
even Alzheimer’s.
Consultant neurologist and sleep
consultant Dr Guy Leschziner told
Optimum Nutrition: “For most people, there
is a clear circadian rhythm, a 24 hour cycle
defined by an area of the brain called the
suprachiasmatic nucleus. But this master
clock coordinates circadian rhythms in all
other organs in the body, and when there
is misalignment between our behaviour
and other physiological processes, there
is evidence that this results in physical
harms, including metabolic issues, immune
dysregulation and even increasing the risk
of cancer.”
This is bad news for shift workers. “Shift
work disorder has even been listed as a
possible carcinogen by the World Health
Organization,” he says. “So it is likely that
fighting against your intrinsic circadian
rhythm is deeply unhealthy.”
The interest in body clock and health
has developed into a whole area of
research called chronobiology. One
recent study even suggested that after
surgery, giving anti-inflammatories in
the morning and analgesic painkillers
in the evening works better with the
body’s circadian rhythm. 2 This is because
inflammation, which is important to the
healing process, signals for cells to repair
tissue. It was hypothesised that giving
anti-inflammatories at night, when the
healing is underway, would interfere with
this process. When researchers compared
bone healing in two different groups
of mice, it was found that mice given
anti-inflammatories in the morning and
analgesics at night, as opposed to antiinflammatories
round the clock, recovered
from the pain of the injury, and regained
bone strength more quickly and more fully.
Circadian rhythm
Although we usually speak of a single
‘body clock’, it has been suggested that
different organs have their own circadian
rhythm. Research last year on mice even
suggested that some of these circadian
clocks may work independently of the
brain. After shutting down the entire
circadian clock before jump starting those
for the liver and skin, scientists found
that these circadian clocks responded
to light independent of the brain. 3,4 In
other research, it was found that a type of
immune cell helps to keep time in the gut;
potentially explaining why disruption to
eating patterns can cause gastrointestinal
problems. 5
It perhaps even seems logical that
different parts of the body should have
their own rhythm — because the body
cannot do everything all at the same
time. For instance, we can’t eat, exercise
and defecate all at the same time — or
if we can, we probably shouldn’t. This is
because the body focuses resources on
the task in hand; if we are feeling anxious
we are unlikely to be wondering what to
have for lunch. This is because whilst we
are in fight or flight mode, the digestive
system temporarily shuts up shop — it
would be hard to eat whilst running from a
sabretooth tiger.
Hormones are important for this. Before
we wake up, our so-called ‘stress’ hormone
cortisol rises and peaks, enabling us to
start the day by drawing on stored energy
so that we don’t have to function on empty.
This is triggered by daylight; and at the end
of the day, reduced light triggers secretion
of a hormone called melatonin, which
makes us sleepy.
Response to light
According to a recent study of cells
taken from the eyes of deceased human
donors, three types of cells (which
are not involved in sight) responded
when exposed to light; 6 firing after just
a 30-second pulse of light. When the
light was turned off, some of the cells
took several seconds to stop firing. The
discovery is thought to explain why some
blind people have a body clock that follows
a day-night cycle even though they cannot
see. It also demonstrates how light is a
stimulant to the human body at a cellular
level.
The importance of sleep
Good quality sleep — something many of
us are short on — is vital to the circadian
rhythm. During sleep, the body undergoes
a range of housekeeping chores, healing
and repairing. For example, one study
published this year 7 reports that a type of
collagen that is important to connective
tissue is broken down and replenished
during sleep. So when we don’t get
enough sleep, the body doesn’t get to
carry out all its tasks efficiently.
Also, at the very least, it is known
that tiredness makes us crave highcalorie
foods, which are then processed
differently. More nutrients eaten when
tired end up being stored as fat, so even
if we eat the same foods as when rested,
we are more likely to gain weight. This is
why some experts recommend that we try
to sleep and eat according to those ancient
rhythms; getting as much daylight as
possible during the day, quality darkness at
night, and avoiding eating when our bodies
are preparing for sleep.
Late night eating has also been
associated with poorer health long-term. In
one small study of 112 women, presented at
the American Heart Association’s (AHA)
Scientific Sessions in November 2019, it
was reported that women who ate a higher
proportion of their daily calorie intake later
in the evening were more likely to be at
greater risk for cardiovascular disease. The
AHA said that each one per cent increase
in calories consumed in the evening
increased the likelihood of higher blood
pressure and body mass index, and poorer
long-term control of blood sugar.
In an AHA statement, lead study author
Nour Makarem, PhD, said: “So far, lifestyle
approaches to prevent heart disease have
focused on what we eat and how much
we eat. These preliminary results indicate
that intentional eating that is mindful of
the timing and proportion of calories in
evening meals may represent a simple,
modifiable behaviour that can help lower
heart disease risk.”
Diet, dopamine and disruption
Whilst artificial light and a wealth of
distractions act to disrupt our circadian
rhythm, what we eat can also play a
“...intentional eating that is mindful of the timing and proportion
of calories in evening meals may represent a simple, modifiable
behaviour that can help lower heart disease risk”
SPRING 2020 | OPTIMUM NUTRITION
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