Does Lactoferrin Boost Immunity? Both COVID Trials Were Null

By Erin Rose · Updated July 19, 2026 · Methodology

Educational overview — not medical advice. This site does not claim lactoferrin prevents or treats COVID-19 or any infection; the trials below are presented as a direct rebuttal to that marketing claim, not as an open question. This statement has not been evaluated by the FDA. This product is not intended to diagnose, treat, cure, or prevent any disease.

Start with the clinical question, not the mechanism

Lactoferrin's proposed immune mechanisms — iron sequestration that starves iron-dependent bacteria, and some immunomodulatory cell-signaling effects — are well established in vitro and in animal work. That mechanistic and observational plausibility is real, but it's outside the scope of this page and this evidence base, which is built entirely on verified human trials. Mechanism is not proof of a human clinical outcome, and nothing on this page should be read as implying it is. The question this page answers is narrower and more useful: when lactoferrin has actually been tested in a human randomized trial for an infection-related clinical outcome, what happened?

The two COVID-19 trials: both clean nulls

Navarro, Paredes, Tucto, Medina, Angles-Yanqui & Nario 2023, published in Biometals, was a double-blind randomized controlled trial in 209 healthcare workers at two Lima, Peru tertiary hospitals (104 given bovine lactoferrin, 105 placebo), 600mg/day for 90 days. Its primary endpoint — SARS-CoV-2 infection prevention — was not met: 10.6% of the lactoferrin group was infected versus 8.6% of the placebo group (IRR 1.23, 95% CI 0.51-3.06, p=0.64) — a clean null, numerically trending the wrong way, though not statistically significant. The trial was stopped early once COVID vaccines became available in Peru, which reduced its statistical power — a real limitation, but not a reason to read this as anything other than an honest null; it certainly isn't evidence of benefit.

Matino, Tavella, Rizzi, Avanzi, Azzolina & Battaglia 2023, published in Nutrients as the LAC Randomized Clinical Trial, was a double-blind RCT in 218 hospitalized adults with moderate-to-severe COVID-19 (113 lactoferrin, 105 placebo), 800mg/day oral bovine lactoferrin. It had two primary endpoints, and neither was met: death or ICU admission (RR 1.06, 95% CI 0.63-1.79) and discharge or clinical recovery within 14 days (RR 0.85, 95% CI 0.70-1.04). The authors' own conclusion is unambiguous: the findings "do not support its use in hospitalized patients with moderate-to-severe COVID-19." This is a clean, well-powered negative trial — there's no caveat that softens the headline here. Any "lactoferrin treats or prevents COVID-19" claim is directly contradicted by these two, the best dedicated RCTs on the question.

The 2026 inflammation trial: interesting, but a different kind of endpoint

The most current and highest-quality general-immune trial in this evidence base is Berthon, Williams, Williams, Budden, Hiles & Bartlett 2026, published in The British Journal of Nutrition: a randomized controlled trial in 103 healthy adults 50 and older (97 completed), 4 weeks, comparing 600mg/day (high dose) against 200mg/day (low dose) and placebo. The primary outcome wasn't a single named endpoint in the abstract; it was reported as a panel of immune and inflammatory markers. Key findings: the high-dose group had reduced plasma IL-6 and CRP compared to the low-dose group, and increased total and CD4+ T cells compared to placebo; the low-dose group had reduced neutrophil frequency and activated CD8+ T cells compared to placebo. In an ex-vivo rhinovirus (RV-16) challenge, the high-dose group blunted the virus-induced IL-6 response (p=0.001) and boosted IFN-α2 compared to the low-dose group (p=0.04). This is a genuinely interesting, current signal — but it's a short (4-week), surrogate-marker and ex-vivo-challenge study, not a clinical "fewer colds" outcome. Don't let this trial get overstated into a clinical-benefit claim; it measured what happens to blood markers and cells in a lab, not what happens to a person's actual infection risk.

The respiratory-infection meta-analysis: real, but mostly not about adults like you

Ali, Hasan, Kow & Merchant 2021, published in Clinical Nutrition ESPEN, reviewed 9 RCTs and pooled 6 quantitatively (n=1,194), finding a significant reduction in respiratory tract infection risk (pooled OR 0.57, 95% CI 0.44-0.74, roughly a 43% relative risk reduction) — the primary endpoint, met. This is a real, replicated pooled effect. But the population is dominated by infant-formula-fortification trials, not adults taking a lactoferrin capsule for immune support, which limits how directly it applies to the typical retail buyer. Two of the nine reviewed studies were rated high risk of bias, and one author disclosed a scientific-advisory-board role for a lactoferrin supplement product (no direct financial tie stated). The authors themselves called for "a large well-designed RCT," and specifically flagged the COVID-19 question as unresolved at the time of writing — a question the two dedicated COVID trials above then answered with a null.

Verified lactoferrin products

If you're interested in the general-immune signal rather than a COVID-specific claim, here's how the lactoferrin products we track and verify compare.

Frequently asked questions

Related

• Lactoferrin: what it is & who it's for
• Lactoferrin for iron-deficiency anemia — the site's other retraction-honest deep dive
• Lactoferrin dosage guide — why the COVID trials' higher doses still found nothing
• Best lactoferrin
• Zinc for immune system & colds — the site's other immune-support category with its own evidence grading
• Does elderberry work for colds & flu? — another honest, mixed-evidence immune category

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