Why Test Based Nutrition

Zinzino Gut Health Test

What we measure
This test focuses on three scientifically essential compounds:

• Indole-3-propionic acid (IPA) – IPA level – a beneficial metabolite produced exclusively by gut bacteria from dietary tryptophan. Higher levels are linked to stronger gut barrier integrity and protection against oxidative stress. IPA is increasingly recognised as a key indicator of gut microbiota function and overall resilience.

• Tryptophan (TRP) – an essential amino acid obtained from the diet that serves as the precursor (starting material) for both IPA and kynurenine. Tryptophan availability and how it is metabolised can influence gut health, immune function and metabolic balance.

• Kynurenine (KYN) – a metabolite produced from tryptophan through the kynurenine pathway, often activated by increased immune stress. Higher kynurenine levels and an elevated KYN:TRP ratio are linked to increased immune activation and a shift away from beneficial microbial metabolite production.

We also calculate these key ratios:

• IPA:TRP ratio – Gut microbiome efficiency – reflects the proportion of dietary tryptophan converted by gut bacteria into IPA, influenced by gut microbiota composition and diet.

• KYN:TRP ratio – Immune stress indicator – an established marker of immune activation and load.

• IPA:KYN ratio – Microbiome immune support – a relative balance score showing the relationship between protective and stress-driven pathways in tryptophan metabolism.

Your report also includes a Gut Health Index, integrating all measured markers and ratios into a clear, easy-to-understand overview of your gut-immune-metabolic balance.

Why tryptophan metabolism matters

Tryptophan metabolism is increasingly recognised as a critical hub connecting gut, immune, brain, and metabolic health. Gut bacteria transform tryptophan into a range of indole metabolites, including IPA – a health-supporting metabolite that supports gut barrier integrity, modulates immune responses, and helps protect against oxidative stress.
Emerging research shows that higher IPA levels are linked to metabolic flexibility, glucose regulation, and immune function. Conversely, when tryptophan metabolism is dysregulated, more of it is diverted into the kynurenine pathway – a route often triggered by your body’s stress responses.
This metabolic crossroad between the body and gut bacteria is no longer a scientific curiosity – it is now seen as a cornerstone of intestinal and systemic homeostasis. By decoding your tryptophan metabolism profile, this test reveals the functional output of your gut bacteria and how it relates to immune and metabolic pathways – empowering you to make targeted, evidence-based changes to support long-term health from the inside out.

Why Test Based Nutrition

By Dr Colin Roberston