Reading the Certificate of Analysis (COA): How to Spot Quality Supplements

Not all supplements are created equal—but how can you tell which ones are worth it? A Certificate of Analysis (COA) is one of the most important tools for verifying quality, purity, and transparency. Here’s how to read one and what to look for.

🔍 What is a COA?

A Certificate of Analysis is a document provided by an independent lab verifying what's inside a supplement. It shows:

• The actual ingredient amounts

• The presence (or absence) of contaminants

• The accuracy of the label

• Lab credentials and testing methods

👉 Brands that publish COAs are serious about transparency and product integrity.

Key Sections of a COA

1. Product Identification

• Lists the supplement name, lot number, and manufacturer

• Confirms the lab tested the exact batch you’re buying

  
  

2. Ingredient Breakdown

• Includes active ingredients, their concentrations, and how they compare to the label

• Look for values close to or within ±10% of the label claim

  
  

3. Microbial Testing

• Checks for harmful bacteria like E. coli, Salmonella, or yeast/mold

• Should read “Not Detected” or show safe levels

  
  

4. Heavy Metals & Contaminants

• Tests for arsenic, lead, mercury, and cadmium

• Values should fall below limits set by organizations like the US Pharmacopeia (USP) or NSF International

  
  

5. Lab Credentials

• Make sure the lab is ISO 17025 accredited, which means it's certified for accuracy

• Labs like Eurofins, NSF, and UL are commonly used

  
  

Red Flags to Watch For

• No lab name or accreditation info

• COA not batch-specific

• Values wildly different from label claims

• Contaminant levels close to or over the limit

• Missing heavy metal or microbial testing

  
  

Why It Matters

Reading a COA empowers consumers to demand better supplements and reject mystery blends. It’s a cornerstone of transparent wellness and smart affiliate recommendations.

Whether you’re comparing magnesium powders or coaching-friendly greens blends, a COA helps you cut through marketing fluff and choose clean, credible products.

Sources

• How to Read a Supplement COA – Labdoor

• ISO 17025 Overview – ANSI

• USP Limits for Heavy Metals in Supplements

• NSF International – Supplement Testing Programs