Side by side

Compare supplements

Put up to three ingredients next to each other. See where the evidence, dosing, timing, and tradeoffs differ.

Supplement 1Supplement 2Supplement 3

Measure

Add a supplement

Evidence

Strong evidence

Common protocol700–900 mcg RAE/day total intake for most adults——

Protocols mapped

1 goal-specific

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Timing

With a meal containing fat

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Expected effect

Days to months when intake or status is inadequate

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Primary uses

Nutritional adequacyVisionDeficiency correction

Watch for

Headache or nausea with excess preformed vitamin A · Liver toxicity at high chronic doses

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