The lining of the intestine and gut microbiome make the gut highly selective in absorbing specific nutrients. When this gut lining is compromised, unwanted substances can cross the barrier and activate an immune response. The test works on the principle that small molecules are readily absorbed by the gut and excreted in the urine, whilst larger molecules are not. Under normal circumstances the ratio of large molecules to small molecules is low. Where ‘leaky gut’ is present, the larger molecules are found to penetrate the gut lining and are detected in the urine.
This urine test assesses levels of a synthetic sugar and mannitol that can be used to monitor improvements or deterioration in intestinal permeability.
Lactulose is a 'large' molecule, and only small levels should be absorbed by the gut and excreted into the urine.
Mannitol is a 'small' molecule which is readily absorbed by the gut and subsequently excreted into the urine.
Where 'leaky gut’ is present, the large synthetic sugar molecules can penetrate the gut lining and are recovered in the urine, resulting in a high recovery ratio.
You’ll receive your urine test kit in the mail, along with logistics for your sample collection.
Mail your sample back to the lab according to the instructions provided with your kit. Please be aware of our festive season lab closures (Dec 19th 2025 - January 5th 2026) when returning your samples and ensure samples are posted no later than 12th December 2025, or after 2nd January, to allow for processing.