How We Grade Supplement Brands A Through F

Not all supplement brands are created equal. A bottle of magnesium from an NSF-certified manufacturer with third-party testing and GMP compliance is a fundamentally different product than one from an unverified brand with no testing documentation.

LongevityGraph grades every supplement brand on a deterministic A-F scale. No AI opinions, no subjective reviews — just data.

The Scoring Framework

Our brand quality score evaluates 35+ boolean and tiered attributes across four categories, weighted by their impact on product quality:

Certifications (50% weight)

This is the dominant factor, and for good reason. Third-party certification is the single best indicator of supplement quality.

• NSF International / NSF Certified for Sport — Tests for label accuracy, contaminant levels, and banned substances. The gold standard.
• USP Verified — United States Pharmacopeia verification for potency and purity.
• ConsumerLab Approved — Independent testing against label claims.
• Informed Choice / Informed Sport — Tests for substances banned in competitive sports.

A brand with NSF certification gets a significant scoring boost. Multiple certifications compound.

Manufacturing (25% weight)

• GMP Certified — Good Manufacturing Practice compliance (FDA-required but often poorly enforced)
• FDA Registered Facility — The facility is registered with the FDA
• In-house Laboratory — The brand operates its own testing lab
• cGMP Compliant — Current GMP, the stricter standard

Testing & Transparency (15% weight)

• Third-party Testing — Uses external labs for verification
• COA Available — Certificate of Analysis publicly accessible
• Batch Testing — Each production batch is independently tested
• Heavy Metal Testing — Specifically tests for lead, mercury, arsenic, cadmium

Regulatory History (10% weight, penalty-based)

• FDA Warning Letters — Major penalty
• FDA Recalls — Major penalty
• Lawsuits — Moderate penalty
• Advertising Issues — Minor penalty

Grade Boundaries

Examples

Grade A brands include Thorne, Pure Encapsulations, and Life Extension. They typically carry NSF or USP certification, operate in-house labs, publish certificates of analysis, and have clean regulatory records.

Grade B brands like NOW Foods and Nordic Naturals have good manufacturing practices and some certifications but may not carry the top-tier NSF/USP marks across all products.

Grade D-F brands are typically store brands, Amazon marketplace sellers, or manufacturers with no verifiable testing documentation. This doesn’t mean their products are harmful — it means there’s no independent verification that what’s on the label is actually in the bottle.

Why This Matters

Studies consistently show that supplement label accuracy varies dramatically by brand. Independent testing by ConsumerLab and others has found:

• 20-30% of supplements don’t contain the amount of active ingredient listed on the label
• Some products contain contaminants (heavy metals, microplastics) not disclosed on the label
• “Proprietary blends” often contain trivial amounts of expensive ingredients

A quality grade helps you make informed decisions before you buy.

Check Your Brands

Use our free supplement evaluator to check the grade of any supplement brand. Or search the DSLD database to compare products across 214,000+ indexed supplements.