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STACK·IT·UP

Best picks

Best supplements for immune support

Fewer sick days, year-round — starting with the deficiencies everyone has.

Immune support isn't built the day you feel a tickle. It's built quietly over months, mostly by fixing the two deficiencies nearly everyone has: vitamin D and zinc.

Then a probiotic to support the 70% of your immune system that lives in your gut.

The picks

Top 4 for immune support

  1. #1
    Vitamin D3 + K2

    Single highest-impact pick. Most adults run low, especially in winter. 2,000–5,000 IU daily with K2.

    Dose
    2000–4000 IU
    When
    morning
    Full breakdown →
  2. #2
    Zinc

    Critical for immune cell development. 15–25 mg daily; take with food to avoid nausea.

    Dose
    15 mg
    When
    morning
    Full breakdown →
  3. #3
    Vitamin C

    Modest effect on cold duration. 1–2 g at the first sign of illness, not a daily megadose.

    Dose
    500 mg
    When
    morning
    Full breakdown →
  4. #4
    Probiotic (Multi-strain)

    Multi-strain probiotic supports gut barrier and the immune tissue that lives there.

    Dose
    10–30 B CFU
    When
    morning
    Full breakdown →

Before you buy

  • Megadosing vitamin C past 2 g/day just gives you GI upset — more isn't better.
  • If you take zinc long-term, add 1–2 mg copper to prevent deficiency.

Common questions

  • Does elderberry actually help?

    Modest evidence for shortening cold/flu duration if started within 48 hours. Not a daily staple.

  • How fast does vitamin D raise blood levels?

    6–8 weeks. The real endpoint is fewer sick days across a full season.

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