Supplement · graded by use, two uses
Lactoferrin
Respiratory and systemic symptom scores in healthy adults.
Grade C: human trials exist, but they are small, mixed or not yet repeated. This is not a finding that it does not work. How to read a grade →
Lactoferrin is a protein found in milk. In two studies by its maker, healthy adults taking it reported milder cold symptoms. In one, illness ended about a day sooner. But it did not lower how many people got sick. So it did not prevent colds, and the symptom result comes only from its maker.
The C belongs to one of the two uses graded on this record. The other one carries its own letter.
As studied, and the trials
Oda et al. (Nutrients, 2023; PMID PubMed ID: the permanent number the US National Library of Medicine gives a published paper. Each one links to that paper's record on PubMed. 37764743): symptom scores lower on 200 mg/day over 12 weeks in 145 analyzed adults, with more dropouts on lactoferrin than placebo An inactive substitute made to look like the real treatment, so participants cannot tell which one they received.. Oda et al. (2021; PMID 32151562): the same sponsor, site and lead author, 310 adults; illness duration about a day shorter, no difference in how many got sick. Two trials from one maker, not independent replication The same finding reproduced by a separate research group. A result seen once can be chance or bias; a replicated one is harder to explain away., on self-reported scores: C.
As studied, and the trials
Tested and no benefit in adults: the maker's 310-person trial found no difference in infection prevalence (Oda et al., 2021; PMID 32151562), an independent 90-day trial in health workers found no reduction in SARS-CoV-2 infection (Navarro et al., 2023; PMID 36474100), and the pooled adult odds ratio is 1.00 (Berthon et al., 2022; PMID 35481594). The reduction in infants and children in the same pooling is a different population and is not graded here.
Read the grade that matches your goal. How EBL grades by use →
- Dose studied
- 200 mg/day
- Form graded
- Bovine lactoferrin
- Evidence behind the C
- PMID 37764743 →PMID 32151562 →
A letter describes the human evidence, not the product, the manufacturer, or the ingredient's worth.
See the full evidence record →Funding: Both trials this Grade C for Respiratory and systemic symptom scores in healthy adults rests on were funded by the maker of the product they tested. The funder's role in design and analysis is not stated here, because the full trial reports could not be read. The letter is what the trials support under the grading rules; the funding is stated here so it can be weighed alongside it. Investigators: Both trials this Grade C for Respiratory and systemic symptom scores in healthy adults rests on were run by investigators employed by, founded by, or belonging to the organization that developed, sells or teaches the intervention (the maker of the lactoferrin tested, with five of nine authors on its staff; the maker of the lactoferrin tested, with five authors on its staff). The funder may read non-commercial; the people who ran the trials are part of the organization whose intervention they tested, which is stated here so it can be weighed alongside the letter.
Respiratory and systemic symptom scores in healthy adults. Respiratory infection prevention: tested, no benefit (D).
Why this gradeGrade C, small or unreplicated trials. The reasoning, and what the grade does not cover.
Grade C, the record's best use: respiratory and systemic symptom scores in healthy adults, on two trials from the product's maker. Oda et al. (Nutrients, 2023; PMID 37764743) found symptom scores lower on 200 mg/day over 12 weeks, in a full analysis set with more dropouts on lactoferrin than placebo; Oda et al. (2021; PMID 32151562), the same sponsor and lead author, found illness about a day shorter and no difference in how many people got sick. Maker-run self-report findings without independent replication are C, and the funding is stated beside the letter. PREVENTING INFECTION IN ADULTS IS D ON ROUTE 2: the maker's own larger trial found no difference in prevalence, an independent trial in health workers found no reduction in SARS-CoV-2 infection (Navarro et al., 2023; PMID 36474100), and the pooled adult odds ratio is 1.00 (Berthon et al., 2022; PMID 35481594).
WHAT THIS GRADE DOES NOT COVERinfants and children, where the pooled analysis found fewer infections; preterm infants and late-onset sepsis (Razak et al., 2021; PMID 31529448), a separate population; iron status; and the dendritic-cell activation markers, which are mechanism rather than outcome.
A grade describes the human evidence for a named use. It is not advice, and it is not a judgment on any individual prescription. How the letters are decided →
Who responds: this record's trial reading reports no subgroup that identifies who responds.
As studied: dose, form, population and duration for every use
A grade describes the intervention that was tested. Where the product on the shelf differs from it, this says so.
How this letter has changed · latest: October 2026 · Corrected
The record rested on one maker-run trial and called it the only adult trial. The same maker's larger trial (Oda et al., J Microbiol Immunol Infect, 2021; PMID 32151562; 310 adults) shortened illness by about a day and found no difference in how many people got sick; an independent 90-day trial in health workers (Navarro et al., Biometals, 2023; PMID 36474100) found no reduction in SARS-CoV-2 infection; and the pooled adult odds ratio for respiratory infection is 1.00 (Berthon et al., Adv Nutr, 2022; PMID 35481594). Graded by use: symptom scores C on the maker's trials, with the funding stated; infection prevention in adults D on Route 2. The 2023 trial's full analysis set and dropout imbalance are now stated. Headline unchanged at C. Applied the written grade definition under the editor's standing instruction of October 2026 (Arnold Sandlow, D.C.).PMID 32151562 PMID 35481594 PMID 36474100
Funding stated beside the letter. The single adult trial, Oda 2023 (PMID 37764743), states that research funds and test foods were provided by the company that makes the lactoferrin tested, and five of its nine authors are its employees. Letter unchanged.PMID 37764743
Every change to a letter on this site is dated and published. The full evidence log →
Commercial disclosure
EBL earns no commission on any supplement it grades. A purchase made through the dispensary link below pays EBL nothing, the practitioner discount goes to you in full. The dispensary is Fullscript, a practitioner dispensary, and many of the professional-grade brands in it are sold mainly through practitioners rather than in health food stores. Grades are assigned by published rubric before any commercial relationship exists and are never influenced by one. Full disclosure.
200 mg/day (bovine lactoferrin; Oda 2023 adult RCT Randomized controlled trial: people are assigned to the treatment or a comparison by chance, so the groups differ only in what they received. It is the design that can show cause and effect.)
Standardized extracts/forms were used in the cited trials; product quality varies.
In the cited 12-week trial, two tablets a day were held in the mouth for a few tens of seconds and then swallowed (PMID 37764743). The report does not state a time of day.
Checked against the full published report. What the cited trials did, not a schedule. Every supplement, by trial timing →
Cow's milk protein allergy. Lactoferrin is a milk glycoprotein, and the label is not always explicit about it.
Iron: lactoferrin binds iron and changes how it is handled, so timing relative to an iron supplement or an iron-binding drug matters. No prominent drug interaction otherwise.
Iron absorption from lactoferrin has been measured with stable isotopes. The record says lactoferrin binds iron and changes how it is handled, so timing relative to an iron supplement matters. That has been measured directly rather than inferred. A crossover A trial design in which each participant receives both the treatment and the comparison, one after the other, and serves as their own control. stable-isotope study in 25 Kenyan infants compared iron absorption from labeled ferrous sulfate alone, from labeled ferrous sulfate given together with bovine apo-lactoferrin, and from intrinsically labeled holo-lactoferrin: absorption was greater from apo-lactoferrin, and holo-lactoferrin and ferrous sulfate were similar. An earlier randomized study measured absorption from recombinant human lactoferrin in young women. Two limits worth carrying: the isotope work is in infants on a maize porridge, and earlier infant studies had reported that lactoferrin either did not change or inhibited iron absorption, so the direction is not settled across populations. The timing caution stands, and it now rests on measurement. Mikulic et al. (J Nutr, 2020;150(12):3200-3207; PMID 32886113): randomized crossover stable-iron-isotope study in Kenyan infants of apo-lactoferrin, holo-lactoferrin and ferrous sulfate. Lonnerdal et al. (Am J Clin Nutr, 2006; PMID 16469988): randomized study of iron absorption from recombinant human lactoferrin in young US women.
Serum iron and ferritin for iron-metabolism applications at baseline and 8 weeks. For immune applications, track IgA levels and frequency of upper respiratory infections over a 3-month period. For gut health, track inflammatory markers (CRP, calprotectin) at baseline and 12 weeks.
Primary evidenceFive papers, each linked to its PubMed record.
Oda et al. (Nutrients, 2023; PMID 37764743): 157 healthy adults, bovine lactoferrin 200 mg/day for 12 weeks; respiratory and systemic symptom scores and plasmacytoid dendritic-cell activity improved against placebo in the full analysis set of 145, with more dropouts on lactoferrin (10) than placebo (2). Funded by the maker, which supplied the product; five of nine authors are its employees. Oda et al. (J Microbiol Immunol Infect, 2021; PMID 32151562): the same sponsor's larger trial, 310 adults randomized to placebo, 200 or 600 mg for 12 weeks in summer; illness duration shorter (2.0 against 3.0 days) and no difference in the prevalence of infection or in immune markers; five authors are the maker's employees. Independent: Navarro et al. (Biometals, 2023; PMID 36474100), 209 Peruvian health workers, 600 mg/day for 90 days, SARS-CoV-2 infection 10.6 against 8.6 percent, no difference, stopped early when vaccines arrived. Berthon et al. (Adv Nutr, 2022; PMID 35481594): systematic review A review that searches for every study on a question using a method set in advance, then assesses them together. and meta-analysis A study that pools the numbers from several trials into one combined estimate., 25 studies; respiratory infection incidence lower in infants and children (OR 0.78) and not in adults (OR 1.00, 95% CI 0.76 to 1.32); IL-6 lower in adults, CRP unchanged. Razak et al. (Am J Perinatol, 2021; PMID 31529448): preterm-infant late-onset sepsis meta-analysis, separate population, context only. Grade C on symptom scores from the maker's trials; D on Route 2 for preventing infection in adults.
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