20 | New Scientist | 26 October 2019300 500Women Men0 100
Choline
(milligrams)Here is how much choline you would get
from eating 100 grams of various foods
compared with the recommended
minimum intake in the USBeef liverHuman milk
Beef steak
Salmon
Pork chops
Chicken
Almonds
Broccoli
Baked beans
Milk
White riceHard-boiled
eggSOURCE: doi.org/dcstWHETHER we follow it or not,
most of us know the standard
advice for eating healthily. Not
too much red meat, fill up on
whole grains for fibre, eat oily
fish for the omega-3 oils, and
have plenty of fruit and veg for
the vitamins and minerals.
But there is another essential
nutrient that most of us have
never heard of – and that standard
advice may be stopping us getting
enough of it. The substance iscalled choline and Emma
Derbyshire at Nutrition Insight,
a consultancy in Surrey, UK,
recently argued in the journal
BMJ Nutrition, Prevention &
Health that a lack of it might be
an emerging public health crisis.
It is still unclear exactly how
much choline we need. But
because eggs and red meat are
some of the best sources of
choline, the trend for eating fewer
animal products could mean we
are missing out on a vital nutrient
without knowing it. Even those
of us who eat meat might not be
getting enough.
In the past, most vitamins
were discovered because people
who were malnourished got a
characteristic disease that was
cured when they ate certain
foods. Sailors deprived of fresh
fruit got scurvy because they
lacked vitamin C, for example.
Choline’s history is less
straightforward. It was first
isolated from bile in 1862 and was
later found to play many roles in
the human body. It makes up cell
membranes, and is important in
the liver’s fat metabolism. It also
helps make a nerve signalling
molecule called acetylcholine,found in the brain and muscles.
It was thought, though, that
the human body could make its
own choline. It produces plenty
of other biochemicals, and
there was no known choline
deficiency disease.
That was questioned in the
1980s, partly because of studies
showing that some animals get
sick on a diet lacking in choline.
Steven Zeisel at the University
of North Carolina then devised
a definitive test by getting
volunteers to stay in hospital
for several weeks eating only
the food provided.
His team created a baseline diet
with very little choline – mainly
salads, a soy-based protein
shake and bread rolls. Some
people got rolls with added
choline, some didn’t.
Within a few weeks, the
volunteers who got rolls without
choline had more liver enzymes
in their blood and their livers
accumulated fat. When they were
switched onto the choline-laced
bread, they recovered. “I hadThere have also been a few
small trials to see if giving
pregnant women higher doses
of choline helps their fetuses’
brain development. Results are
mixed, but one of the longest trials
showed that when the women
took twice the recommended dose
of choline while pregnant, their
children did better at a simple
memory task when 7 years old.
“There’s something very special
about this nutrient,” says Marie
Caudill at Cornell University in
New York, who helped run the trial.
Choline might not just affect
the brain while it is developing.
Studies in mice suggest that
higher choline intake in
adulthood staves off the effects
of dementia, although trials in
people haven’t yet been done.The neglected nutrient
The importance of choline is becoming clear – and if you are cutting
down on meat you may not be getting enough, says Clare WilsonEating a plant-based
diet? You may be low
on cholinediscovered the first new
nutrient since the basic
vitamins,” says Zeisel.
Because of this and other
lines of research, choline was
reassessed. It turned out that
human breast milk is rich in
choline, and that pregnant women
pump it across their placenta.
Levels can be 10 times higher in
fetuses than in mothers’ blood.
That had to be for a reason.
It is now accepted that adult
livers can make some choline, but
most of us don’t produce enough
to meet the body’s requirements.
In 1998, the US Institute of
Medicine advised that men should
consume 550 milligrams a day and
women 425 mg (more if they are
pregnant or breastfeeding).
Most people don’t hit that level.
Surveys suggest that average daily
intake ranges from 260 to 470 mg.
Large numbers of people aren’t
being hospitalised with liver
failure, though, so perhaps the
original targets were too high.
They were based on Ziesel’s study
that compared just two diets,
one with 500 mg of choline
a day and one with 50 mg. It is
possible that some intermediate
level is enough.
Still, some people may need
more choline than others. About
one in three people in the US have
a mild case of fatty liver. This is
usually blamed on unhealthy
eating. But Zeisel says lack of
choline may be responsible in
some cases. He has shown that
people with fatty liver are more
likely to have certain gene variants
that mean they make less choline.
However, the biggest concern
over choline intake is connected
to fetal brains. Animal research
suggests that choline is needed
to build brains: when pregnant
mice are deprived of choline,
their babies do worse at mental
tasks like negotiating mazes.NutritionNews Insight
“ It is now accepted that
adult livers can make some
choline, but most of us
don’t produce enough”