How We Grade Supplement Brands A Through F
Our brand quality scoring system evaluates 35+ attributes across certifications, manufacturing practices, testing transparency, and FDA compliance. Here's the methodology.
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 is built from 35+ boolean and tiered attributes across four scoring categories — weighted by their impact on product quality — minus penalties for red flags. The maximum is 100 points.
Certifications (50 points)
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 or USP certification gets a significant scoring boost. Multiple certifications compound.
Testing (25 points)
- Third-party Testing — Uses external labs for verification
- COA Available — Certificate of Analysis publicly accessible
- Heavy Metal Testing — Specifically tests for lead, mercury, arsenic, cadmium
- Potency & Microbial Testing — Confirms label-claimed actives and screens for contamination
Manufacturing (15 points)
- GMP / FDA-Registered Facility — Good Manufacturing Practice compliance at a registered facility
- NSF GMP Registration — Independently audited GMP
- ISO 17025 Lab — Accredited in-house testing laboratory
- Made in USA / EU — Manufactured under stricter regulatory regimes
Product Quality (15 points)
- Bioavailable Forms — Uses the better-absorbed form of each ingredient
- No Artificial Fillers — Clean excipient profile
- Transparent Sourcing — Discloses ingredient origin
- Published Research — Brand-backed clinical studies
Penalties
Points are deducted for red flags, and an active Class I FDA recall is an automatic F regardless of score:
- Active Class I FDA Recall — Automatic F
- Proprietary Blends — Penalty (undisclosed amounts)
- Recent Quality Controversy — Penalty
Grade Boundaries
| Grade | Score Range | What It Means |
|---|---|---|
| A | 70-100 | Top-tier brand with strong certifications and transparent practices |
| B | 50-69 | Good quality with some certifications; may lack full testing transparency |
| C | 30-49 | Adequate basic manufacturing but limited or no third-party certification |
| D | 15-29 | Below average quality; minimal verifiable quality assurance |
| F | 0-14 | No certifications, no testing documentation, or regulatory red flags |
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 214,300 indexed supplements.
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