Ask VitaminDB

Cited answers about supplement value, cost per dose, dosing and forms — drawn only from our catalog and NIH-sourced facts. Every answer links the VitaminDB pages it draws from. Not medical advice.

Catalog data as of 2026-09-13

How to avoid overpaying

Compare cost per active unit — elemental mg, EPA+DHA, or IU — not per capsule or per bottle. Two labels can price the same “per pill” yet differ several-fold per active dose.
The cheapest form may be poorly absorbed — magnesium oxide is the classic example: cheap per milligram, but your body takes up relatively little. Weigh absorption, not sticker price alone.
A larger count isn’t automatically cheaper per dose — divide price by servings before you decide. Our rankings do this for you.

Or browse all nutrients, goals, or the price-spread study.

References & sources

We link primary sources and paraphrase their findings — never copy their text, tables, or images. Cost-per-dose figures are our own first-party catalog data.