Processed food in diet may confuse immune system

Immune systems can no longer tell the difference between healthy cells and an attacking virus or bacterium.

A classic Aussie hamburger.

Diets high in processed food could be causing an increase in the number of people developing auto­immune diseases around the world, scientists say.

According to experts at the Francis Crick Institute in London, people are suffering because their immune systems can no longer tell the difference between healthy cells and an attacking virus or bacterium.

James Lee and Carola Vinuesa are leading two separate research groups at the institute to help identify why autoimmune diseases, in which the body attacks its own tissue and organs, are on the rise. The diseases cover a range of conditions, including type 1 diabetes, rheumatoid arthritis, inflammatory bowel disease and multiple sclerosis.

The increase in cases in the West began about 40 years ago and is now being seen in countries in the Middle East and east Asia. The relatively recent adoption of processed fast food in these countries could be to blame, the scientists say. “Human genetics hasn’t altered over the past few decades. So something must be changing in the outside world in a way that is increasing our predisposition to autoimmune disease,” Dr Lee told The Observer.

Autoimmune disease cases are estimated to be rising internationally by between 3 and 9 per cent a year.

Professor Vinuesa, who was previously based at the Australian National University, said the introduction of a western-style diet around the world was contributing to the increase.

“Fast-food diets lack certain important ingredients, such as fibre, and evidence suggests this alteration affects a person’s microbiome — the collection of micro-organisms that we have in our gut and which play a key role in controlling various bodily functions,” Professor Vinuesa said.

“These changes in our micro­biomes are then triggering autoimmune diseases, of which more than 100 types have now been discovered.”

Although lifestyle is a key factor in the development of auto­immune disease, “genetic susceptibilities” make some people more vulnerable.

Professor Vinuesa added: “There is not a lot we can do to halt the global spread of fast food franchises. So instead, we are trying to understand the fundamental genetic mechanisms that underpin autoimmune diseases and make some people susceptible but others not. We want to tackle the issue at that level.”

To do this, the scientists are using new techniques that enable them to pinpoint very small DNA differences among large numbers of individuals to identify common genetic patterns among those suffering from an autoimmune disease. They hope this method will help to develop targeted treatment as there are so many types of autoimmune disease with different genetic pathways.

“We have lots of potentially useful new therapies that are being developed all the time, but we don’t know which patients to give them to because we now realise we don’t know exactly which version of the disease they have,” Professor Vinuesa said. “That is now a key goal for autoimmune research. We have to learn how to group and stratify patients so we can give them the right therapy.”

The Times