Immune & Respiratory

Immune Support

Reviewed by the Nimbera editorial team · Last updated May 2026

General support for the immune system through nutrition and supplementation to help the body resist infection and recover more quickly.

When to see a doctor

Seek medical care if you experience recurrent infections, fever above 39°C (103°F), symptoms lasting more than 10 days, or any signs of a serious illness.

Natural remedies · 6

Tap any remedy for the full how-to and citation.

How we rate evidence▾

Strong - Multiple randomised controlled trials or systematic reviews with consistent positive outcomes.

Moderate - At least one RCT or several high-quality observational studies with plausible mechanisms.

Limited - Small trials, animal studies, or traditional use with limited human clinical evidence.

Sources link directly to PubMed, Cochrane Reviews, or NCCIH.

Vitamin C (100-200 mg/day)

Carr & Maggini (2017, Nutrients, PMID 29099763) reviewed evidence that vitamin C supports neutrophil chemotaxis, phagocytosis, and microbial killing. A meta-analysis of 53 trials cited in the same review found prophylactic doses reduced cold duration by 8% in adults and 14% in children, and halved cold incidence in people under extreme physical stress.

$5-$15 for a 3-month supply at 200 mg/day.

Vitamin D3 (cholecalciferol)

Martineau et al. (2017, BMJ, PMID 28202713) conducted a meta-analysis of individual participant data from 25 RCTs (n=10,933). Daily or weekly vitamin D supplementation reduced the odds of acute respiratory infection (aOR 0.81, 95% CI 0.72-0.91). Individuals with severe baseline deficiency showed the greatest benefit (aOR 0.30, 95% CI 0.17-0.53).

$8-$20 for a 3-month supply at 1,000-2,000 IU/day.

Elderberry Extract (Sambucus nigra)

Zakay-Rones et al. (2004, J Int Med Res, PMID 15080016) conducted a double-blind, placebo-controlled RCT (n=60, ages 18-54) during the 1999-2000 influenza season. Participants receiving 15 ml elderberry syrup four times daily for 5 days recovered on average 4 days earlier than placebo, with significantly less rescue medication use.

$15-$35 per bottle (1-2 weeks of treatment-dose use).

Zinc (supplemental, immune-support dose)

Wessels, Maywald & Rink (2017, Nutrients, PMID 29186856) reviewed how zinc ions regulate intracellular signalling in both innate and adaptive immune cells via Toll-like receptor and T-cell receptor pathways. Gombart, Pierre & Maggini (2020, Nutrients, PMID 31963293) identified zinc among the micronutrients with the strongest evidence for immune support, noting that adequate intake is essential at every stage of the immune response.

$6-$18 for a 3-month supply at 15 mg/day.

Astragalus

Yang L et al. 2025 Phytomedicine (PMID 40208321) - systematic review of 31 RCTs found astragalus membranaceus supplementation significantly increased CD3+ T-cell count (MD +8.79, p < 0.001) and CD4+/CD8+ ratio compared to control, indicating enhanced cellular immune function in clinical populations.

Beta-Glucan

Akramiene D et al. 2007 Medicina (PMID 17895634) - review of clinical evidence found beta-1,3/1,6-glucans derived from baker's yeast and mushrooms activate innate immunity through dectin-1 and CR3 receptors on macrophages and natural killer cells, enhancing phagocytosis and cytokine production without overstimulating adaptive immunity.

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Remedy information is compiled from primary clinical sources including PubMed, the Cochrane Library, and the National Center for Complementary and Integrative Health (NCCIH). Evidence ratings reflect published human trial data at time of writing. This content is for informational purposes only and is not a substitute for professional medical advice. Read our full disclaimer.