Ingredient Library

This library is a label-reading resource. It explains what to compare on a supplement label without recommending a product or making treatment claims.

How to read a supplement label

• Start with the serving size and servings per container.
• Compare the amount of each dietary ingredient per serving, not only the front-label claim.
• Review the ingredient form, source, plant part, or standardization only when the label states it.
• Read other ingredients and all cautions.

Omega-3 fatty acids

Compare the source and the stated EPA and DHA amounts per serving. “Fish oil” or “omega oil” weight is not necessarily the same as the EPA and DHA total. See the NIH Office of Dietary Supplements omega-3 fact sheet.

Vitamin C

Compare the amount per serving and the labeled form. Check the % Daily Value in the Supplement Facts panel. See the NIH Office of Dietary Supplements vitamin C fact sheet.

Zinc

Compare the zinc amount per serving and do not rely only on the compound name or front label. See the NIH Office of Dietary Supplements zinc fact sheet.

Turmeric and ashwagandha

For botanicals, review the plant part, amount per serving, extract details, and standardization only if they are explicitly stated on the label. The National Center for Complementary and Integrative Health Herbs at a Glance provides independent background information.

Official labeling references

For details on Supplement Facts and dietary supplement labels, see the U.S. Food and Drug Administration Dietary Supplement Labeling Guide.

This page is educational and is not medical advice. Always review the product label and consult a qualified healthcare professional when appropriate. Last reviewed: July 30, 2026.