Immune Support Protocol

ASolid confidence

Trusted recommendation.

Low commitment6 steps · 4 supplements · 2 habits

Latest evidence update: 2026-12-01

Open as constellation

What this protocol does

Evidence-based supplements and habits to maintain robust immune function year-round.

What to expect

Synthesized from research on this protocol's components. Individual response varies.

Weeks 4–8

Look for: With consistent vitamin C at 500-2000 mg/day, endothelial function (a vascular health marker measured by flow-mediated dilation) significantly improves, and modest blood pressure reduction becomes detectable.

Not yet expected: Reliable cold or flu prevention from vitamin D — evidence on vitamin D alone or combined with calcium for immune function outcomes is inconsistent across studies.

Backed by 3 studies

Effect of vitamin C and vitamin E supplementation on endothelial function: a systematic review and meta-analysis of randomised controlled trials.
Nutraceuticals with a clinically detectable blood pressure-lowering effect: a review of available randomized clinical trials and their meta-analyses.
Vitamin D and Calcium: A Systematic Review of Health Outcomes (Update).

Weeks 8–12

Daily vitamin D3 at 4000-5000 IU reliably raises 25-hydroxyvitamin D blood levels, building the foundation for any downstream benefits.

Expected outcomes

Research outcomes from 5 supplements and habits (23 data points)

Outcome estimates are derived from published research and represent population-level associations, not guaranteed individual results. Consult a healthcare professional before making decisions based on these estimates. Combined effects account for shared biological mechanisms between interventions.

Protocol steps

Vitamin D3supplementSHigh confidence Context-aware

With meal · 4000-5000 IU

Activates T cells — most common immune-related deficiency

Cutaneous vitamin D synthesis is minimal above 35° latitude from October through April (northern hemisphere) or May through October (southern hemisphere). Outside this window, prioritize 15-30 min of midday sun exposure; supplementation is optional.

Vitamin CsupplementASolid confidence

Divided doses · 500mg 2x daily

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Order these supplements

Get everything you need for this protocol delivered to your door.

Vitamin D3

4000-5000 IU

Vitamin C

500mg 2x daily

Zinc

15-30mg

NAC (N-Acetyl Cysteine)

600mg

Questions about Immune Support Protocol

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Research behind the components

Aggregated from the supplements and habits in this protocol; not a composite protocol grade · 1216 studies referenced

Referenced studies (1216)

ProtocolEngine provides general health information based on published research. This is not medical advice. Consult a healthcare professional before starting any supplement or health protocol.