What does ultra-processed food do to our gut flora?

How does the content of ultra-processed food affect our intestinal flora?

Wilhelm Glomm hopes to get answers by studying the digestive system and the intestines. He is a researcher at SINTEF's Department of Biotechnology and Nanomedicine.

“What happens in the gut is really important. In this complex system you'll find more than two-thirds of the body’s immune system, and what we eat has a major impact on our gut microbiota," he says.

This includes all the microorganisms found in the gut, such as bacteria, viruses, and fungi. The gut microbiota changes over time and with age and reflects the state of the body, the researcher explains.

No clear definition of ultra-processed food

According to the Norwegian Food Safety Authority, there is no universal and unifying definition of ultra-processed food. 

But this refers to industrially processed food that often contain additives. It may be difficult to recognise the raw ingredients the food is made from.

Glomm and his research team have analysed stool samples from a selection of volunteer women, men, and one infant. 

Analyses of the composition of the gut bacteria showed which metabolites they are made up of.

Metabolites are small molecules. They are produced when gut bacteria digest and convert food, drugs, and other substances. These metabolites are then released into the body and can influence our health.

"We then examined the relationship between gut bacteria and differences in age, gender, and diet,” says Glomm.

This made it possible to see the relationship between what people eat and what metabolites the gut flora produces.

Some gut bacteria can make it easier to regulate weight

The researchers found a big difference in bacterial diversity between adults and infants. They also found that diet affects the composition of the bacteria in the gut. 

This in itself was not surprising.

But the research team also found a clear connection between certain gut bacteria and the metabolites they produce, and these can be linked to the participants' diets.

“We saw that some gut bacteria caused the metabolites to produce tryptamine. This is a good metabolite that helps the body regulate weight and is also anti-inflammatory,” says Glomm.

The data showed large differences in how much tryptamine is produced in the intestines of the different individuals.

Tryptamine can again be traced back to ruminococcus, a type of bacteria that converts the amino acid tryptophan – which we find a lot of in meat, eggs, fish, and dairy products – into tryptamine.

People who ate these protein sources were found to have enough of this good tryptamine. Those with a vegetarian diet had less. 

Diet can therefore affect the bacteria in our intestines. And this can affect our intestinal health.

Emulsifiers – a scapegoat?

Emulsifiers are additives that make it easier to mix oil and water in ultra-processed foods. Emulsifiers in particular have been linked to a number of health challenges, such as obesity and inflammation of the intestines.

“Adding an emulsifier ensures a fine distribution of the oil droplets in the mixture. An example is béarnaise sauce, where the egg yolk acts as an emulsifier to finely distribute the oil and the rest of the ingredients,” explains Glomm.

The researchers therefore looked at a selection of widely used emulsifiers in different concentrations, both with and without oil. The goal was to see how intestinal cells react to the different concentrations.

“We found that a solution of emulsifier in water caused severe damage to the intestinal cells and dissolved the cell layer, and in some cases even killed the intestinal cells. Where oil was present, we didn’t see any damage," he says.

Studied the effect of emulsifiers

The researchers then studied the effect of emulsifiers on a mixture of good and bad gut bacteria. 

They added a selection of emulsifiers, both with water and with oil present, and looked at how the composition of intestinal bacteria changed over time.

“We found that the experiments were very similar to experiments with intestinal cells. The impact was minimal if oil was present,” says Glomm.

However, more research is needed on whether emulsifiers are unhealthy or not. Glomm argues the results show that we should be aware of the possible harmful effects of the emulsifiers, but that more studies need to be done with an even larger sample.

“However, this study has also provided important information that we can use to find connections between food and various health challenges, such as intestinal inflammation, obesity, and diabetes,” he says.

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