New Scientist Australian Edition - 24.08.2019

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

YULIA GUSTERINA/ALAMY STOCK PHOTO

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