Why "proper nutrition" doesn't work the same for everyone

The main conclusion:

our gut bacteria have their own "chemical cookbook", and everyone's is unique - it is particularly disrupted in chronic diseases.

The work is published in the journal Nature Microbiology, reports Friedrich Schiller University of Jena.

The microbiome as a "second chemical factory"

Many beneficial plant compounds from berries, nuts and vegetables are not active as we eat them. They must first be "finalised" by microbes in the gut - a kind of "second digestion".

The researchers

• systematically tracked the fate of 775 plant phytonutrients,

• and compared them to how they're processed by gut bacterial enzymes.

It turned out that:

• on average, up to 70% of all enzymes in the microbiome are potentially involved in processing these substances - a much higher proportion than previously thought;

• and the enzyme mix is highly individualised:

  • differs from person to person,

  • depends on the region,

  • it's linked to dietary habits.

Prof Gianni Panagiotou, Head of the Microbiome Dynamics at Jena and Leibniz-HKI, emphasises:
without the combination of bioinformaticians, chemists, disease modellers and microbiologists, it would be impossible to see the whole picture.

When the "cookbook" fails

Using artificial intelligence, the team compared microbiome enzyme profiles:

• in healthy individuals,

• patients with inflammatory bowel disease,

• colorectal cancer patients,

• people with non-alcoholic fatty liver disease.

Results:

• in patients with chronic disease, the ability of the microbiome to process beneficial plant matter was markedly reduced;

• aI models discriminated between healthy and diseased patients with high accuracy by enzyme recruitment of gut bacteria;

• for example, patients with colorectal cancer lacked a key enzyme for processing a particular plant compound that was widely present in healthy controls.

The authors suggest:
"this is why general dietary recommendations for the chronically ill often fail to have the expected effect - their microbiome simply doesn't know how to properly 'cook' beneficial substances."

Step to personalised nutrition

To break down all these connections, scientists:

• analysed more than 5,500 gut microbiomes of people from around the world,

• used bioinformatics to predict possible reactions,

• then tested them in the lab on promising strains of bacteria.

This data sets the stage for the personalised nutritional science of the future. Instead of a one-size-fits-all "eat more vegetables," it will be possible to:

• analyse the microbiome of a specific individual,

• to select foods that their microbes can actually convert into useful metabolites,

• or supplementing the microbiome with probiotics with the right enzymes.

The study emphasises: it's not just the composition of the microbiome (what bacteria live in the gut) that matters, but also its function - what it actually does to our food on a chemical level.

The scientists offer a key to how to maintain this balance through individualised nutritional strategies.