How to Read a Supplement Label: 8 Things to Check

Quick Answer

The eight things that matter most on a supplement label: (1) form of the active ingredient, (2) dose per serving, (3) number of servings, (4) third-party certifications, (5) excipients and fillers, (6) whether the dose matches clinical trials, (7) proprietary blend warnings, and (8) expiration and lot number.

Key Takeaways

• "1000 mg of turmeric" may contain only 20 mg of curcumin — always look for the active compound percentage
• Proprietary blends hide individual ingredient doses — a red flag
• Third-party certifications (USP, NSF, Informed Sport) verify label accuracy and purity
• Serving size vs container size: a "60-capsule bottle" taken twice daily is only 30 days
• Expiration date matters most for probiotics and omega-3s

1. Active Ingredient Form

The form determines absorption. Examples where form critically matters:

Always read the ingredient name in parentheses — that is the actual compound.

2. Clinical Dose

Compare the label dose to what was used in published trials. A common trick: labels list ingredients at sub-therapeutic doses to keep costs low while making label claims.

Example: Ashwagandha clinical trials use 300–600 mg KSM-66 extract. A product listing "100 mg ashwagandha root" is providing less than one-third of the evidence-based dose.

3. Proprietary Blends

If you see "Proprietary Stress Support Blend — 500 mg" containing five ingredients, you have no idea how much of each is present. The blend total (500 mg) may be 490 mg of cheap filler and 10 mg of the expensive active ingredient. Avoid proprietary blends for evidence-based supplementation.

4. Third-Party Testing

Look for these on the label:

• USP Verified — tests identity, potency, purity, dissolubility
• NSF Certified for Sport — includes banned substance testing
• Informed Sport — independent anti-doping certification
• ConsumerLab — independent periodic testing of brands

Without certification, you are trusting the manufacturer. FDA does not approve supplements before sale.

5. Excipients to Avoid

6. Serving Size vs Servings Per Container

"30 servings" at 2 capsules per serving = 60 capsules. If the product shows "2 capsules = 1 serving" and you need 3 capsules for the clinical dose, the bottle lasts 20 days, not 30.

7. Expiration and Storage

• Probiotics: Refrigerated varieties expire faster; check viability at expiration, not at manufacture
• Omega-3: Look for freshness indicators (TOTOX value) or choose brands that publish oxidation testing
• Fat-soluble vitamins (A, D, E, K): Degrade slowly; expiration is less critical
• B vitamins: Light-sensitive — prefer dark bottles