It's often lumped in the 'new age' category with Gwyneth Paltrow's raw food or Pete Evans' paleo diet, but the natural eating movement is far from new.

In fact, its roots extend back to Nazi Germany — and beyond.

'Leave our food as natural as possible' was a slogan coined in 1942 by Nazi physician Werner Kollath.

"The Nazis were very concerned with regenerating the Aryan body, so they had this big push to get people into healthier lifestyles," says Dr Corinna Treitel, associate professor of history at Washington University.

But, she says, a precedent of prioritising health for political gain was established well before then.

"The Nazis are really just a particularly nasty example," she says.

"This dream of eating naturally has been politically promiscuous in many different cultures. It goes all the way back to the mid-19th century."

Hungry people 'tend to riot'

The Nazis were interested in health for two main reasons, Dr Treitel says.

Firstly, it supported their 'master race' ideology.

"They really cared about propagandising health practices that would support the Aryan body," Dr Treitel says.

"Eating more naturally, eating organic, eating less meat, less refined sugar and other processed foods was part of that health promotion in a racial sense."

Ideas of nationalism were also relevant to eating natural foods, says University of Newcastle eugenics researcher Dr Sacha Davis.

For the Nazis, 'natural' was aligned with ideas of 'blood and soil', or Blut und Boden, a popular Nazi slogan.

"There is this idea that the natural food for the German or the Aryan body is the food that grows from German soil," Dr Davis says.

Natural foods aligned with Nazi nationalist ideas, such as those encapsulated in the slogan Blut und Boden, 'blood and soil'. ( Getty Images: ullstein bild Dtl. )

The second main reason Nazis propagandised natural eating relates to their concern about losing another world war to hunger.

"Hunger had been one of the things that had defeated them in the First World War and they wanted to make very sure that Germans ate well during the next war," Dr Treitel says.

"When people get hungry they tend to riot, and they tend to doubt the legitimacy of their own government."

She says hunger was a huge problem on the German home front from about 1915 onwards.

"By 1917 it had gotten so bad that respectable people were stealing potatoes and bread," she says.

"People who had never been out on the streets to protest before were out on the streets protesting. It was really a very serious crisis for the German government."

Sorry, this audio has expired Dr Corrina Treitel explains how much of today's push towards natural food is because of the events in Europe during World War 2.

This, Dr Davis says, shows natural eating was also about economics.

Self-sufficiency — the ability to survive without relying on foreign imports — was a priority for the Nazis, he says.

"Hitler had this belief, that many right-wing Germans had, that Wilhelm's Germany in the First World War fell because the home front broke — and the home front broke because there wasn't sufficient food."

It was thought that self-sufficiency — and the dietary changes it encompassed — would provide a shield to this danger.

Germany didn't produce enough meat to meet its needs and so it imported meat — pork and beef — from abroad, Dr Davis says.

Self-sufficiency would mean eating less of it.

Local fish replaced meat, wheat and white bread was replaced with German-grown rye, and quark replaced butter.

The aim of replacing imports with domestic products was "really driving" the natural eating agenda, Dr Davis says.

'Leave our food as natural as possible,' says the heading in this 1942 hand-drawn illustration by Nazi physician Werner Kollath. ( Supplied )

Not using artificial additives or eating overly processed foods was considered not only healthier, but more economically efficient.

"If you consume wholegrain bread instead of white bread you're making better use of the grain, you're using more of the grain and so as a result the food goes further and that economic factor is always in the background," Dr Davis says.

Nazis picking up on older concerns

The Nazis were not unique in their concern for producing healthier people.

Rather, consideration about the impacts of health on society arose with industrialisation, which brought with it health challenges, Dr Davis says.

"[The Nazis] picked up on concerns that were much older in society, going back to before the first world war, that urban society was polluted and unhealthy," he says.

"It was leading to people living in cramped and horrible conditions.

"They were eating bad foods, they were consuming alcohol and tobacco, and this was actually resulting in physical damage to their bodies."

He says this led to fears of "racial degeneration" — the idea that generations to come were being impacted by people's poor health.

"There is a broader public health movement and concern with public health — so it's less about the health of the individual and more about the health of the individual as a member of society, producing future generations of the society," he says.

"That's something that emerges in the early 1900s."

In this period, he says, promotion of healthy eating isn't restricted to Germany and isn't always "a strongly racial idea".

"Sometimes it's much more about public health," he says, something many doctors in different countries were concerned about.

There was "very big" concern in in Germany and central Europe, but also in the UK, Sweden and America, Dr Davis says.

"[It was] tied to the ideas of eugenics more generally, that you can make healthier people."

Old natural eating ideas still relevant

The Nazis fell from power in 1945, but Dr Treitel says natural food has remained an important part of German culture.

"Organic farming is still very, very popular in Germany," she says.

"The current German Government even has an unofficial policy now of sustainable agriculture which is really built on some of these ideas that the Nazis also promoted."

There could be an enduring economic imperative for natural eating — albeit a different one from the fascist era.

"You can actually feed many more people ... I'm not the first person to say this, you can talk to economists who will say essentially the same thing," Dr Treitel says.

"Eating naturally is much more efficient on your resources than eating our typical industrialised diet of lots of meat, lots of refined sugar, lots of imported foods and so on.

"You can feed many more people from one plot of land if you feed them a vegetarian diet rather than trying to feed them from the meat that you raise from animals who eat that same food."