Diet drinks, chewing gum and table-top sweeteners can increase the risk of metabolic diseases such as Type 2 diabetes, heart disease and stroke because ingesting aspartame, saccharin and sucralose makes our bodies less able to break down sugars with insulin, scientists have shown.
It’s all to do with the gut microbiome – the collection of microorganisms that live in our intestines and help us extract energy from food. While we have long known that our guts are host to a diverse ecosystem made up of bacteria and other organisms, scientists are just beginning to understand the role that this microbiome plays in health and disease.
Now, research published in Nature on 17 September has shown that artificial sweeteners lead to glucose intolerance by altering the composition and function of the gut microbiome.
‘Artificial sweeteners have become so prevalent that the vast majority of our foods contain these substances,’ said Dr Eran Elinav, principal investigator on the EU-funded META-BIOME project at Israel’s Weizmann Institute of Science and one of the authors of the paper. ‘We’ve discovered that artificial sweeteners may induce glucose intolerance in subsets of individuals, and they do this by altering the gut microbiota.’
‘This study suggests that a commonly used food ingredient that we’ve all been taking for many years as a measure to fight obesity and metabolic syndrome may contribute, in some individuals, to the same epidemic which we aim to prevent.’
Dr Eran Elinav, principal investigator, Weizmann Institute of Science, Israel
Researchers studied the gut microbiomes in both mice and humans, and found that some bacteria in the microbiome grew in number and some died back as a result of ingesting artificial sweeteners. These altered microbiomes seem to break down food differently from the normal digestive process, ultimately increasing the body’s ability to gather energy from food in the gut and leading to glucose intolerance.
‘Overall, this study suggests that a commonly used food ingredient that we’ve all been taking for many years as a measure to fight obesity and metabolic syndrome may contribute, in some individuals, to the same epidemic which we aim to prevent,’ said Dr Elinav.
The META-BIOME project, led by Dr Elinav, who received a grant from the European Research Council (ERC), examines the complex interactions between gut bacteria, the cells lining the gut and the body’s innate immune response. The researchers are trying to establish how these interactions combine with genetic and environmental factors to result in a tendency to develop metabolic diseases.
‘We’ve already discovered that a number of important environmental factors related to diet and lifestyle can alter the healthy composition and function of our microbiome,’ said Dr Elinav. ‘We are now continuing our quest to understand how these altered microbiomes drive disease and ways by which we can intervene in this pathological process.’
Mapping the microbiome
As yet scientists lack a definitive picture of the exact composition of a healthy microbiome. However, the working theory is that if the microbiome deviates from its normal state, it can contribute to the development of metabolic syndrome – a group of diseases that includes obesity, lifestyle-related Type 2 diabetes, fatty liver disease, inflammatory bowel disease, hypercholesterolemia – and related complications such as heart disease and stroke.
By understanding more about what a healthy microbiome looks like, how it interacts with the body and what factors cause it to change, scientists hope to reach the stage where such diseases are predictable and preventable.
‘We envision that we’d be able to characterise a person’s genetic code and microbiome together, predicting ahead of time a person’s disease susceptibility,’ said Dr Elinav. ‘Moreover, we speculate that this understanding will enable us to intervene and “correct” microbiome interactions in a way that would enable us to prevent or treat disease in a personalised way.’
He said that individual variations in the gut microbiome could mean that some people are naturally more prone to the damaging effects of artificial sweeteners than others.
Eat to beat disease
One of the ways we can positively affect the make-up of our gut microbiome is through what we eat. Researchers on MyNewGut, an EU-funded international research project, are looking into how changes in diet could help the gut microbiome prevent metabolic syndrome, as well as obesity and diet-related behavioural disorders.
The MyNewGut team is made up of researchers from 15 EU and non-EU countries and includes experts in microbiology, nutrition, physiology, immunology, brain research and computational modelling, as well as partners from the food industry. It aims to not only identify biomarkers – biological early warning signs – on the microbiome that could help anticipate and prevent disease, but also to identify specific dietary interventions that could improve health.
‘One of the main challenges for the project is to go beyond basic research and use the scientific data to inform new dietary recommendations, creating new food products and ingredients that will help reduce the burden of diet-related diseases,’ said project leader Professor Yolanda Sanz, from the Spanish National Research Council.
Although our understanding of the microbiome is at a relatively early stage, Dr Sanz said that researchers on the project, which is due to end in 2018, are working closely with partners from the food industry and professional associations to make their findings available and ready for practical application as soon as possible.
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