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1. What counts as a probiotic?

Use precise terminology before selecting or developing a product.

PROBIOTICS

Live microorganisms that, when administered in adequate amounts, confer a health benefit on the host.

A probiotic claim should be supported by evidence relevant to the strain and intended use.

PREBIOTICS

Substrates selectively used by host microorganisms that confer a health benefit.

They are not live microorganisms; they serve as resources for selected microbes.

LIVE

Defined microorganism(s)

FOOD

Selective microbial substrate

Important: fermented food or a product labelled “probiotic” does not automatically establish a proven health benefit.

Sources: Hill et al. (2014); Gibson et al. (2017). See References on slide 6.

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2. Possible mechanisms of probiotic action

Mechanisms vary by strain, host, environment and experimental context.

PROBIOTIC

STRAIN

COMPETITION

Compete for binding sites

and nutrients

METABOLITES

Produce organic acids

and other compounds

BARRIER SUPPORT

May influence epithelial

barrier function

IMMUNE SIGNALS

May modulate host

immune responses

PATHOGEN ADHESION

May reduce pathogen

attachment

ENVIRONMENT

Can alter local pH

and microbial conditions

These are plausible mechanisms—not a guarantee that every strain produces every effect.

Conceptual synthesis informed by probiotic consensus and review literature.

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3. A staged development workflow

The source presentation outlines culture optimization, screening and confirmation.

CULTURE OPTIMIZATION

Define growth medium and conditions; document reproducible cultivation.

PRELIMINARY SCREENING

Compare candidate isolates using a prespecified screening method.

CONFIRMATORY TESTING

Repeat promising findings with appropriate controls and quantitative measures.

CHARACTERIZATION

Identify the strain and assess safety, stability and intended function.

EVIDENCE REVIEW

Interpret results against the intended application and the limits of the data.

Document protocols, controls, replicates and exclusion criteria before interpreting results.

Workflow is a teaching framework adapted from the topics shown in the supplied module.

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4. How to evaluate a candidate's activity

Use complementary tests; do not infer clinical benefit from a single laboratory result.

IN VITRO: INITIAL EVIDENCE

Agar-based assay

Useful for preliminary comparison; diffusion can affect results.

Co-culture / broth

Can test interaction under defined conditions.

Confirmatory tests

Include controls, concentration/time series where relevant, replicates and quantitative readouts.

IN VIVO / CLINICAL EVIDENCE

Preclinical models

May address host context; cannot by itself establish human benefit.

Human studies

Ethically designed studies evaluate safety and outcomes in the target population.

Interpret cautiously

A positive in-vitro result is not equivalent to demonstrated efficacy or safety in humans.

Separate three questions: Does the candidate show activity? Is it safe for intended use? Is a health benefit demonstrated?

Framework synthesized from FAO/WHO evaluation guidance and the ISAPP consensus statement.

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5. From candidate strain to responsible claim

A development decision should follow evidence—not assumptions.

IDENTITY & QUALITY

Use well-characterized strains and reliable methods.

SAFETY

Assess risks for the intended population and application.

EFFICACY

Match claims to the evidence and study design.

DATA

REVIEW

CLAIM

A claim should be proportionate to the strength and scope of the evidence.

REFERENCES

• FAO/WHO (2002). Guidelines for the Evaluation of Probiotics in Food. fao.org/4/a0512e/a0512e00.pdf

• Hill et al. (2014). ISAPP consensus on probiotics. Nature Reviews Gastroenterology & Hepatology 11, 506–514. doi:10.1038/nrgastro.2014.66

• Gibson et al. (2017). ISAPP consensus on prebiotics. Nature Reviews Gastroenterology & Hepatology 14, 491–502. doi:10.1038/nrgastro.2017.75

Integrity note: all diagrams in this deck are original PowerPoint shapes. Content is paraphrased and referenced; no original slide images were reused.

Educational overview only; methods and claims must be tailored to the specific strain and intended use.

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