Colostrum (bovine)

What colostrum is

The mammary gland produces colostrum in the first days after birth. It is denser than mature milk and supplies the newborn with antibodies, lactoferrin, antimicrobial peptides and growth factors such as IGF-1. For the calf this is vital, because it is born without its own defenses.

As a supplement, colostrum from dairy cows is defatted and gently dried. Most human studies have used 10 to 20 g of powder per day. That is an amount more reminiscent of a protein powder than of a capsule.

How it is supposed to work

The common explanation is: the immunoglobulins act locally in the mouth, throat and gut, bind germs and strengthen the mucous membrane. Growth factors are said to protect the cells of the gut wall. In cell culture, colostrum dampened heat-induced cell death of intestinal cells and stabilized the electrical resistance of the cell layer.

In humans the picture is more interesting than the textbook story. In a study with 53 active men, infection days decreased, but neither salivary IgA nor neutrophil function changed. Instead, the bacterial load in saliva rose more under placebo than under colostrum. A new crossover study with 16 men saw an oxidative burst of neutrophils about 15 % stronger after a single intake before prolonged cycling. So colostrum measurably changes something in innate immunity. Which part of it explains the less frequent infections, nobody knows yet.

Gut barrier under exertion

Hard endurance exercise, especially in the heat, temporarily makes the gut wall more permeable. Here colostrum provides one of the cleanest individual findings: in a double-blind crossover with 12 volunteers, permeability after exercise rose 2.5-fold under placebo; after 14 days of colostrum, this rise was dampened by 80 %.

A meta-analysis of 10 papers confirms the direction for the lactulose-rhamnose test. That is an established marker of permeability, but still just a marker. Whether this leads to fewer gastrointestinal complaints in competition has not been studied. Anyone who understands the term leaky gut as a diagnosis should know that the studies refer to acute exercise stress and not to a disease.

Case reports

Besides the studies, there is a published case report from Jordan: in an adult with recurrent respiratory infections, these stopped under colostrum, and the microbiome in the nasal swab changed. This is a report on a single person, not proof of efficacy. It does, however, fit the observation from the controlled studies that colostrum acts on the mucous membranes rather than on the classic blood values.

What the studies show

Meta-analysis on respiratory symptoms

In 2016, Jones and colleagues analyzed 5 randomized, placebo-controlled studies with 152 adults who train, duration 8 to 12 weeks. Symptom days: rate ratio 0.56, episodes: 0.62, both significant. The duration of episodes could not be meaningfully pooled, and 4 of the 5 studies had a moderate or high risk of bias. The authors consider the result promising and call for a large confirmatory study.

Winter study with 53 men

Double-blind, 20 g of colostrum or an energy-matched placebo over 12 weeks in winter. The proportion of infection days and the number of episodes were significantly lower under colostrum. Salivary IgA, antimicrobial peptides and neutrophil function remained unchanged, which argues against the mechanisms assumed until then.

Gut permeability after exercise

In the crossover with 12 volunteers, all took colostrum and placebo for 14 days each and then completed a standardized exercise bout. Under placebo, the lactulose-rhamnose ratio rose 2.5-fold; under colostrum, the rise was dampened by 80 %. A later meta-analysis of 10 papers also found a significantly lower ratio, but no difference in the gut damage marker I-FABP.

IGF-1 in the blood

Davison and colleagues tested three scenarios: 40 g once, 20 g daily over 4 weeks, and 20 g daily over 12 weeks with 25 people on colostrum and 29 on placebo. In no protocol did plasma IGF-1 rise. An older study with 60 g daily over 4 weeks also found no change, and doping tests remained negative.

Where the data stop

The infection data are positive but narrow: 152 participants in the meta-analysis, mostly with a risk of bias, and a large, adequately powered study is still pending. A second meta-analysis of 10 studies with 239 participants found no or only a small effect on immunoglobulins, lymphocytes and salivary IgA. So the clinical finding is there, the explanatory mechanism is missing.

On performance, the data are thin. Over 24 weeks, colostrum did not improve performance in 28 soccer players, even though IgG rose and inflammatory markers fell. In a rugby study with 29 players, only jump height rose, by 1.0 cm; strength, endurance and body composition stayed the same, and the frequency of illness did not change. A heat study with 7 trained and 8 untrained men saw no benefit. For use in preterm infants, the authors of a meta-analysis advise against it, because the observed advantage is probably due to a lack of blinding.

Status, approval and legal

In Germany, colostrum is a food and is sold as a dietary supplement. In 2011, EFSA assessed health claims on the immune system, muscle building, performance and recovery; the EU authorized none of them, partly because the product was not sufficiently characterized for an assessment. There is no maximum amount. Colostrum is not banned in sport. Since 2013, WADA has nonetheless advised athletes against consuming it because of its IGF-1 content, although several studies found no rise in the blood.

Safety

No safety problems emerged in the studies over 12 and 24 weeks. Colostrum is milk: it is unsuitable for people with a milk protein allergy, and it contains lactose, which can cause complaints with lactose intolerance and high amounts. The IGF-1 from the powder did not raise blood levels in the studies. Anyone being treated for a hormone-dependent disease should nonetheless discuss intake with a physician beforehand. There is no official upper limit from EFSA, BfR or NIH.

Sources

• Jones et al., BMC Sports Sci Med Rehabil 2016
• Jones et al., Brain Behav Immun 2014
• Główka et al., Nutrients 2020
• Hajihashemi et al., Dig Dis Sci 2024
• Marchbank et al., Am J Physiol Gastrointest Liver Physiol 2011
• Davison et al., Eur J Nutr 2020
• Davison, Nutrients 2021
• Mizelman et al., Eur J Appl Physiol 2026
• Jones, Thatcher, Davison, Eur J Nutr 2026
• EFSA NDA Panel, EFSA Journal 2011