Multivitamin: What It Is, Uses, Evidence & Safety

At a glance

Purpose, evidence and practical considerations.

What it’s for

Filling dietary nutrient gaps

What the evidence says

Benefit depends on diet, deficiencies and the actual formula. A multivitamin is not established as a universal way to prevent cardiovascular disease or cancer.

Confidence: moderate

Safety & interactions

Risk depends on the formula. Vitamin A, iron, vitamin B6, niacin, folic acid and other ingredients can be harmful at excessive doses or in susceptible people, and products can duplicate nutrients from other supplements.

Iron-containing products in people advised to avoid iron
High-dose vitamin A in pregnancy
Nausea
Constipation or diarrhea
Excess intake of individual nutrients
Vitamin K with warfarin
Iron or calcium with some medicines
Overlapping fortified foods and supplements

How it works & important distinctions

A multivitamin supplies multiple micronutrients and can help fill specific intake gaps. Effects depend on the formula and the user's diet; adding nutrients above adequacy does not automatically improve health.

Regulatory status: dietary supplement; no standard US definition fixes the included nutrients or doses

Different forms

The evidence on this page does not automatically apply to:

prenatal vitamins
single-nutrient supplements
proprietary greens powders
therapeutic deficiency treatment

In these protocols

How people use it, with their schedules, context and original sources.

Dr. Mark HymanDr. Mark Hyman's Core Supplement Stack

2-6 capsules · Daily with meals
Foundation supplement - safety net for nutritional gaps

Gabrielle LyonDaily supplements

Date of record:: 26 Jan 2026

Details & sources

She listed a multivitamin among supplements she uses, without a brand, dose or fixed frequency.

Rhonda PatrickDaily supplements

Common dose and timing

Amount and timing patterns reported in public protocols; these are observations, not instructions. Private and hidden usage is excluded.

Typical amount

2-6 capsules1 public entry

Frequency

Daily2 public entries · 100%
Full reported context
daily

Timing

Daily with meals1 public entry · 33%
morning1 public entry · 33%
with first meal1 public entry · 33%

Popular brands

Brand variants reported in public protocols. Private entries are excluded, and inclusion is not an endorsement.

Pure Encapsulations1 public entry

Other items in these protocols

These share a protocol with this intervention. This does not establish that they work together or are suitable alternatives.