14 | New Scientist | 24 August 2019
Nutrition
RADIOACTIVE iron buried in
Antarctic snow must have come
from a cloud of interstellar dust
that Earth has passed through. The
finding suggests that such snow
could tell us more about the clouds
of dust our planet has encountered.
Dominik Koll at the Australian
National University in Canberra and
his team collected 500 kilograms
of Antarctic snow, melted it and
studied its composition. They
found it contained iron-60, a rare
radioactive form of the element.
Koll and his team ruled out
terrestrial sources of iron-60, such
as nuclear power plants. The only
other source would be the explosion
of a star. A supernova could have
littered space with particles
containing iron-60, which then
fell on Earth as it passed through
a cloud of stardust. “I was very
excited when I saw the first counts
of iron-60,” says Koll.
The snow Koll studied was less
than 20 years old. Studying snow
formed at different times could
tell us more about the dust Earth
has travelled through in the past.
At the moment, the solar system
is passing through part of the Milky
Way called the local interstellar
cloud. It has been doing so for
about 45,000 years. We know
this cloud is 30 light years across
but we don’t know much about its
shape or the way its density varies.
Some parts of the cloud might
be more dense than others if they
had material injected into them,
for example by exploding stars.
Looking at dust in older snow
might help us learn more about this.
“I like this idea of using layers of
Antarctic ice to get a tree-ring like
history of deposits of interstellar
grains,” says Angela Speck at the
University of Missouri. ❚
CUTTING carbohydrates has
been shown to reduce migraines,
perhaps by changing the type of
fuel that enters the brain.
The ketogenic diet is a very
low carb diet that makes the
body burn fat for energy instead
of carbs. Aside from aiding
weight loss, it also seems to ease
conditions like epilepsy and
schizophrenia in some people.
Cherubino Di Lorenzo at the
Don Carlo Gnocchi Foundation
in Italy and his colleagues
wondered if the diet might
also help to prevent migraines.
Previous studies have hinted that
it does, but haven’t been able to
figure out whether this is due to
general weight loss or something
specific about reducing carbs.
To find out, the researchers
compared the effects of two very
low calorie diets – one ketogenic
and one not – in 35 overweight
or obese men and women who
experience migraines. Each
person was randomly assigned
a diet that they followed for four
weeks, before swapping to the
other for the same duration.
The two diets used prepared
meals, such as smoothies and
soups, that looked identical. The
meals had the same amounts of
calories and fat but different ratios
of carbohydrates and protein.
Weight loss was similar for the
two regimes, but the ketogenic
diet appeared to be far better at
reducing migraines. About 74 per
cent of people had less than half
the number of migraine-affected
days as normal while on the
low-carb ketogenic diet. This
compares with just 9 per cent
on the high-carb, non-ketogenic
diet (Nutrients, doi.org/c9hw).
In comparison, the best
migraine prevention drugs,
known as CGRP monoclonal
antibodies, cut migraine-affected
days by half or more for between
30 and 48 per cent of users.
The results are compelling, but
larger and longer studies are
needed before the ketogenic diet
can be recommended for migraine
prevention, says Christina Sun-
Edelstein at the University of
Melbourne in Australia. “There
are many migraine treatments
that seem to work well initially
but then are ultimately
disappointing,” she says.
Di Lorenzo thinks that forcing
the body to burn fat rather than
carbohydrates prevents migraines
because the brain adapts by using
compounds called ketone bodies.
These are produced when fatty
acids are broken down for fuel
instead of glucose. In animal
studies, ketone bodies dampen
brain inflammation and stop
the spread of electrical activity
associated with migraines, he says.
The diet might also work
because lower carbohydrate intake
reduces the production of insulin,
a hormone thought to play a role
in migraines, says Di Lorenzo.
The diet sounds gruelling,
but people with migraines are
often desperate for relief, says
Sun-Edelstein. Very low calorie
diets can usually be tolerated for
only about 12 weeks, so there is a
risk migraines could come back
afterwards, says Di Lorenzo.
He and his colleagues are now
planning to test whether the diet
cuts migraine incidence in people
of ideal weight. ❚
Space
A low-carb diet halved
the number of days
people had migraines
Alice Klein
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News
Ketogenic diet for migraines
The body seems to adapt to a low-carb regime in a way that curbs the condition
Interstellar dust
found locked
in Antarctic snow
Abigail Beall
30 light years
Width of the cloud of interstellar
dust that Earth is traversing