Should every supplement have a CoA?

Every supplement is manufactured against a batch specification, so a CoA exists internally for every batch produced under any reasonable GMP. Whether the consumer ever sees it is another question. Brands with strong quality positioning publish CoAs on the website by batch (e.g. some Bulk products) or send them on request. There is no UK legal requirement to publish a CoA to consumers, so absence of a published CoA is not in itself a regulatory red flag, but a brand that refuses to provide one when asked is a meaningful negative signal.

What does GMP certification actually mean?

Good Manufacturing Practice is a system of quality controls covering staff training, facility hygiene, equipment qualification, raw-material qualification, batch records, in-process testing, finished-product testing, and stability testing. In the UK, food-grade GMP is administered through schemes such as BRCGS Global Standard for Food Safety; pharmaceutical GMP is licensed by the MHRA. NSF, USP, and other certifiers run their own GMP audit programmes for dietary supplements, with periodic site inspections. A GMP certificate from a recognised body is a meaningful quality signal but does not, on its own, certify a specific batch — that is what the CoA does.

Is Informed Sport stricter than NSF?

On the substances screened, the two programmes are broadly comparable — both maintain extensive banned-substance lists aligned with the WADA Prohibited List plus adjacent stimulants and contaminants of concern, both detect at typical thresholds around 10 ng/g for most analytes, and both run pre-notification random batch sampling. NSF Certified for Sport publishes a slightly larger named-substance count (often quoted as 270+ vs Informed Sport's 250+), but the lists overlap heavily and the practical difference is small. Where they actually differ is geographical accessibility — Informed Sport tests at a Cambridge laboratory and is more accessible for UK and EU brands; NSF is US-based.

What heavy metal levels are safe?

The reference standards used in supplement CoAs are USP permitted daily exposures (5 µg/day arsenic inorganic, 5 µg/day cadmium, 3 µg/day mercury inorganic, 5 µg/day lead), California Proposition 65 reproductive-and-cancer 'safe harbour' levels (notably lower for lead at 0.5 µg/day), and EU Regulation 1881/2006 maximum levels by food category. There is no single answer to 'what level is safe' because the answer depends on the source of the standard and the amount of product consumed daily. CoAs should report measured values and the standard they are referenced against; that is the comparison the buyer needs.

Can I trust a brand's own CoA?

An in-house CoA is meaningful when the brand's own laboratory is ISO 17025-accredited, uses pharmacopoeial methods, and consistently reports numerical values rather than pass/fail markers. It is less meaningful when no laboratory accreditation is named, methods are not disclosed, or the same generic CoA is used across multiple batches. Independent third-party certification (Informed Sport, NSF, USP Verified, BSCG, Cologne List) adds a layer of independence — the brand does not choose the sample — and is the strongest assurance available to a retail consumer.

Why don't most UK supermarket supplements publish CoAs?

Three reasons. First, there is no UK legal requirement to publish a CoA to consumers, so it is a discretionary marketing investment. Second, supermarket-channel supplements typically compete on price and shelf placement rather than quality narrative, so the marketing return on publishing CoAs is low. Third, supermarket own-brand supplements are generally manufactured under contract by third-party UK or EU producers; the brand owner may have batch CoAs on file but no consumer-facing portal. Customer service can usually obtain a CoA on request even for supermarket lines, but few buyers ask.

Reading a Supplement Certificate of Analysis (CoA): UK Buyer's Guide

Nutripedia Research Team15 April 2026

A Certificate of Analysis is the single most useful document for verifying what is actually in a supplement bottle. We walk through what a CoA tests for, how to tell an in-house CoA from a third-party one, the red flags of a forged CoA, and where the MHRA fits into UK supplement regulation.

Not medical advice

Nutripedia summarises published peer-reviewed research. This content is for informational purposes only and is not a substitute for professional medical advice. Product mentions are not endorsements.

Before You Read This

Nutripedia is a research librarian, not a doctor. Nothing on this page is medical advice. This article is a regulatory and methodology explainer — it does not recommend any product or supplement and does not interpret symptoms. Consult a UK GP, NHS pharmacist, or registered dietitian before starting any supplement, especially if you are pregnant, breastfeeding, on medication, or managing a chronic condition. Information about MHRA, FSA, NSF, Informed Sport, USP, Cologne List, and BSCG below reflects the regulatory and certification landscape as published by those bodies in 2026 and is summarised for buyer-education purposes only.

Our research is based on 12 peer-reviewed studies. View the full evidence database

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Nutripedia is an educational resource. Content is sourced from peer-reviewed studies and does not constitute medical advice. Product mentions are not endorsements. Consult a healthcare professional before starting any supplement.

Reviewed by

Archie Roberts

Founder, Nutripedia — ALDR Ltd

This page summarises published research from PubMed, NHS, EFSA, and SACN. It does not constitute medical advice; consult a qualified healthcare professional before changing any supplement regimen.

Last reviewed: 15 Apr 2026Methodology