How to Read a Supplement Label (and the %DV Trap)

Every number on the panel is per serving, and brands choose the serving. A label boasting 1,000 mg may require four capsules to get there. If you take one capsule a day, divide everything by four. This is the single most common way labels mislead.

Daily Values are intake reference points set by the FDA to prevent deficiency — they say nothing about the doses used in clinical research. Biotin's DV is 30 mcg while hair studies used 2,500–5,000 mcg (and even those lack RCTs in non-deficient people). Vitamin C's DV is 90 mg while immune-support trials commonly used 500–1,000 mg. A product can shout "100% DV!" and still be far below — or above — the dose that was actually studied.

For minerals, the compound weighs more than the mineral itself. 500 mg of magnesium citrate contains roughly 80 mg of elemental magnesium. Good labels state the elemental amount ("Magnesium (as magnesium glycinate) 200 mg"); vague ones don't. The form in the parentheses also decides absorption — zinc bisglycinate absorbs far better than zinc oxide, methylfolate beats folic acid for people with common MTHFR variants, and ubiquinol beats ubiquinone for CoQ10.

Proprietary blends list a total blend weight but hide each ingredient's dose — you cannot verify whether any single ingredient reaches a clinical dose. And the "Other Ingredients" line below the panel is where colorants like titanium dioxide or FD&C dyes, fillers, and coatings appear. Neither zone is on the front of the bottle for a reason.