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 (20 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

Some links on this page may earn us a commission at no extra cost to you. This never influences our evidence grades or recommendations. Full disclosure

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

Build your Immune Support protocol

A two-minute quiz builds a daily plan of habits, diet and supplements around your goals and what you already take. Free, no account needed.

Start the quiz

Questions about Immune Support Protocol

How does this protocol unfold week by week?

Which step in this protocol has the strongest evidence?

What does each step in this protocol contribute?

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.