Bovine colostrum is the first milk a cow makes in the day or two after calving, dense in antibodies, lactoferrin, and growth factors, and it is sold as a single fix for immunity, the gut, and muscle. The evidence is thin and comes mostly from small trials. The steadiest signal is a modest one: in people who train hard, colostrum cut upper respiratory infection days by around 44% across five small trials, and in two small studies it blunted the gut leakiness that heavy exercise causes.
The muscle and anti-aging pitch rests on IGF-1, and swallowed IGF-1 is broken down in the gut, so taking colostrum does not raise your circulating growth factors or build muscle. It is generally safe for people without a milk allergy, and it is expensive. Worth trying for one specific goal; the broad promises around it are not backed by trials.
Findings & Outcomes
What It Is
Bovine colostrum is the first milk a cow produces in the day or two after giving birth, before ordinary milk comes in. It is denser than mature milk in the compounds a newborn calf needs at the start: immunoglobulins, mainly IgG, the antimicrobial iron-binding protein lactoferrin, and a set of growth factors including IGF-1. Supplements are made by collecting this early milk, pasteurizing it, and drying it into a powder or capsule.
Those same components are what supplement makers point to when they describe colostrum as supporting immunity and the gut. The compounds are in the product. Whether they act the way the marketing implies once an adult swallows them is the open question, and the answer differs by claim. Bovine colostrum differs from human colostrum, so its antibodies target cattle pathogens, not human ones, which limits how much of an immune claim the composition alone can carry.
What the Evidence Shows
The steadiest finding is in people who train hard. A 2016 systematic review and meta-analysis pooled five randomized trials, 152 participants in all, of colostrum in regular exercisers. It found about 44% fewer days of upper respiratory infection symptoms (rate ratio 0.56, 95% CI 0.43 to 0.72) and about 38% fewer infection episodes (rate ratio 0.62, 95% CI 0.40 to 0.99) over eight to twelve weeks. The trials were small, and the reviewers judged four of the five to carry a moderate or high risk of bias from incomplete reporting. An earlier controlled study in adult men points the same way: 32% of the colostrum group reported upper respiratory symptoms against 48% on whey, though how long symptoms lasted did not differ.
The second area is the gut. Heavy endurance exercise makes the intestinal barrier temporarily leakier, and two small trials in athletes found colostrum reduced that rise, measured by sugar-absorption tests and stool zonulin. These are surrogate markers of barrier function in samples of 12 and 16 people, not symptoms or disease outcomes. A third strand is mucosal immunity: in 35 distance runners, colostrum raised salivary IgA by 79% over 12 weeks. Salivary IgA is a marker, and the study authors flagged that its meaning is uncertain at that sample size, so a marker moving is not the same as fewer infections.
The trials do not support the bigger claims in two areas. Across gastrointestinal diseases more broadly, systematic reviews find the trials conflicting and the conditions too varied to pool, so the athlete gut-barrier finding does not extend to treating a diagnosed gut disorder. On muscle: in active men and women given 20 g a day of colostrum or whey for eight weeks, treadmill time to exhaustion, one-repetition-maximum bench press, and repetitions to exhaustion did not differ between the groups. Colostrum did not outperform training plus protein.
The mechanism behind the anabolic pitch does not hold. Colostrum contains IGF-1, an anabolic hormone, so the pitch is that swallowing it raises IGF-1 and builds muscle. A tracer study followed labeled IGF-1 after it was swallowed and recovered about 96% as a broken-down fragment and only about 4% intact. Some training trials recorded a small rise in blood IGF-1 on colostrum, but the rise was modest and came with no gain in muscle or strength.
Swallowed IGF-1 is digested before it reaches the blood, so the growth factor in the powder never acts as a hormone in your body.
The evidence for each finding, at its own strength, is below.
The Research & Studies
Everything here is based on the research we have collected and checked, sorted into groups and ordered with the strongest evidence first. Click any claim to open the studies behind it.
How it works
Swallowed IGF-1 is broken down in the gut, about 96%, and does not act as an anabolic hormone
The growth factor IGF-1 in colostrum is mostly broken down when you swallow it rather than absorbed whole, so it does not work as the muscle-building hormone the marketing suggests.
Mero and colleagues (2002) gave athletes 20 g a day of colostrum and, in a companion tracer experiment, followed labeled recombinant IGF-1 after ingestion: gel electrophoresis of serum 60 minutes later showed about 96% of the radioactivity as a 0.6 kDa fragment and only about 4% at the 40 to 90 kDa range of intact IGF-1, indicating near-complete digestion. Serum IGF-1 rose modestly in the colostrum group in that study and in the same group's 1997 trial in male sprinters, but the rises were small and were not accompanied by measured gains in muscle mass or strength attributable to colostrum.
Who this may not transfer to:The training trials included male and female athletes and the 1997 companion trial was in male sprinters; the digestion of oral IGF-1 is a general physiological finding not expected to differ by sex.
Use this to weigh the anabolic marketing: colostrum does contain IGF-1, but it is not delivered intact as a hormone, and any small serum change has not translated into muscle or strength gains in the trials.
The studies · 2
Mero et al., IGF-I, IgA, and IgG responses to bovine colostrum supplementation during training · J Appl Physiol 2002;93(2):732-739
Mero et al., Effects of bovine colostrum supplementation on serum IGF-I, IgG, hormone, and saliva IgA during training · J Appl Physiol 1997;83(4):1144-1151
Colostrum is richer than mature milk in immunoglobulins, lactoferrin, and growth factors
Colostrum contains antibodies, lactoferrin, and growth factors at higher levels than ordinary milk, which is why it is studied, but having them in the powder is not the same as them working once swallowed.
Reviews of bovine colostrum, including Playford and Weiser (2021), document its composition: high concentrations of immunoglobulins (predominantly IgG), lactoferrin, lactoperoxidase, lysozyme, and growth factors such as IGF-1 and transforming growth factors, at levels well above those in mature milk, declining over the first days after calving. These components underlie the immune and gut-barrier hypotheses tested elsewhere on this page; the composition is well characterized, while the clinical effect of ingesting them as an adult is the open question.
Use this as the factual basis for what colostrum is, and keep separate from what it does: the constituents are established, the adult clinical effects are what the graded claims address.
The study · 1
Playford & Weiser, Bovine Colostrum: Its Constituents and Uses · Nutrients 2021;13(1):265
Respiratory Infection
About 44% fewer upper respiratory infection days in people who train, across five small trials
In people who train hard, taking colostrum for a couple of months meant fewer days with cold and sore-throat symptoms, roughly 40% fewer, across five small trials. It is the steadiest finding the supplement has.
The 2016 systematic review and meta-analysis by Jones and colleagues pooled five randomized controlled trials, 152 participants in total, all in adults engaged in regular exercise training, comparing oral bovine colostrum with a concurrent control over eight to twelve weeks. Upper respiratory symptom days fell (rate ratio 0.56, 95% CI 0.43 to 0.72, P < 0.001) and episodes fell (rate ratio 0.62, 95% CI 0.40 to 0.99, P = 0.04). The reviewers judged four of the five included trials to have a moderate or high risk of bias, largely from incomplete reporting, and there were too few data to pool symptom duration.
Who this may not transfer to:The pooled trials included men and women in exercise training; the effect was measured in trained adults and may not transfer to sedentary or general populations.
This is the finding with the most support behind it, and it is still built on five small trials. It applies to people in hard training, taken over a defined block, not to the general population seeking everyday immune support.
The study · 1
Jones et al., Bovine colostrum supplementation and upper respiratory symptoms during exercise training: a systematic review and meta-analysis of randomised controlled trials · BMC Sports Sci Med Rehabil 2016;8:21
Fewer adult men reported cold symptoms on colostrum than on whey, 32% versus 48%
In one study of adult men, fewer of those on colostrum came down with cold symptoms than those on whey, though when they did get sick the illness lasted about the same time.
Brinkworth and Buckley (2003) coded logbooks from double-blind placebo-controlled studies in which men had been randomly allocated to 60 g a day of concentrated bovine colostrum protein (n = 93) or whey protein (n = 81) for eight weeks. After excluding the first week to remove pre-existing infections, a lower proportion of the colostrum group reported upper respiratory symptoms during the following seven weeks (32% versus 48%, P = 0.03, 95% CI -30% to -2%), while the duration of symptoms did not differ (6.8 +/- 4.2 versus 6.0 +/- 4.4 days, P = 0.27).
Who this may not transfer to:The analysis was in men only; whether the same reduction in reported infections occurs in women was not tested here.
A single-sex study using a high 60 g dose and a retrospective coding of symptom logbooks. It points the same way as the pooled meta-analysis but is best read as supporting rather than independent evidence.
The study · 1
Brinkworth & Buckley, Concentrated bovine colostrum protein supplementation reduces the incidence of self-reported symptoms of upper respiratory tract infection in adult males · Eur J Nutr 2003;42(4):228-232
Digestion
Colostrum lowered exercise-induced gut leakiness on lab tests in two small athlete trials
Heavy endurance exercise makes the gut lining temporarily leakier, and in two small studies of athletes colostrum reduced that leakiness on lab tests.
Marchbank and colleagues (2011) ran a double-blind placebo-controlled crossover in 12 volunteers, 14 days of colostrum or placebo before a standardized exercise bout, and found colostrum blunted the exercise-induced rise in the 5-hour urinary lactulose-to-rhamnose ratio, a marker of small-intestinal permeability, with supporting cell-line work on heat-induced epithelial damage. Halasa and colleagues (2017) supplemented 16 athletes during peak training with 500 mg a day of colostrum or placebo (whey) for 20 days; the lactulose-to-mannitol test normalized in the colostrum group and the intervention-related change was significantly lower than placebo, with a smaller but significant effect on stool zonulin.
Who this may not transfer to:Both trials were small and the sex distribution was not clearly reported; results are in trained athletes and may not transfer to non-exercisers.
These are surrogate markers of barrier function in very small athlete samples, not symptoms or disease. The finding is specific to exercise-induced permeability and should not be extended to treating a diagnosed gut disorder.
The studies · 2
Marchbank et al., The nutriceutical bovine colostrum truncates the increase in gut permeability caused by heavy exercise in athletes · Am J Physiol Gastrointest Liver Physiol 2011;300(3):G477-G484
Halasa et al., Oral Supplementation with Bovine Colostrum Decreases Intestinal Permeability and Stool Concentrations of Zonulin in Athletes · Nutrients 2017;9(4):370
Across gut diseases the colostrum trials conflict and are too varied to pool
For actual gut diseases, the trials of colostrum point in different directions and cover very different conditions, so there is no clear across-the-board answer.
The 2024 systematic review by Hajihashemi and colleagues concluded that evidence on bovine colostrum for gastrointestinal diseases is conflicting, summarising clinical trials across varied conditions without a pooled estimate because the diseases and designs differed too much. The earlier 2014 systematic review by Rathe and colleagues on clinical applications of bovine colostrum therapy similarly found the strongest support in specific settings such as infectious diarrhea and chemotherapy-related mucositis, with the overall picture limited by small and heterogeneous trials.
Who this may not transfer to:The reviews pooled trials in mixed populations across several distinct gastrointestinal conditions, which is itself the main reason no single effect can be stated.
Read this as a limitation, not an endorsement: colostrum has been trialed across many gut conditions with inconsistent results, so it is not established as a treatment for any general gut complaint.
The studies · 2
Hajihashemi et al., Therapeutic effects of bovine colostrum applications on gastrointestinal diseases: a systematic review · Syst Rev 2024;13(1):76
Rathe et al., Clinical applications of bovine colostrum therapy: a systematic review · Nutr Rev 2014;72(4):237-254
Immune Function
Colostrum raised salivary IgA by 79% in runners, a marker not tied to fewer infections
Colostrum raised a mucosal antibody in the saliva of runners in one study, but whether that shift means fewer infections is not established, and other immune markers move inconsistently.
Crooks and colleagues (2006) supplemented 35 distance runners (20 men, 15 women, aged 35 to 58) with bovine colostrum or placebo for 12 weeks; median salivary IgA rose 79% in the colostrum group and the time-dependent change from baseline was significant (P = 0.0291), holding after adjustment for training volume and reported respiratory symptoms. The authors cautioned that the physiological meaning is uncertain given the small sample. A 2020 systematic review of immunological outcomes of colostrum in trained and physically active people found effects across the various markers measured to be inconsistent.
Who this may not transfer to:The salivary IgA trial included both sexes; the marker was measured in trained runners and its link to fewer infections was not demonstrated.
Treat a rise in salivary IgA as a marker change, not a proven reduction in illness; the clinical outcome that matters, fewer infections, is covered by the respiratory claims and rests on separate, limited evidence.
The studies · 2
Crooks et al., The effect of bovine colostrum supplementation on salivary IgA in distance runners · Int J Sport Nutr Exerc Metab 2006;16(1):47-64
Glowka et al., Immunological Outcomes of Bovine Colostrum Supplementation in Trained and Physically Active People: A Systematic Review · Nutrients 2020;12(4):1023
Muscle And Strength
Colostrum did not improve strength or endurance beyond whey plus training
In one small trial, colostrum did not improve strength or endurance compared with whey protein, though there was a small difference in how body composition shifted.
Antonio and colleagues (2001) randomized active men and women to 20 g a day of bovine colostrum powder or whey protein for 8 weeks while training aerobically and with resistance at least three times a week. None of the performance measures, treadmill time to exhaustion, one-repetition-maximum bench press, or submaximal repetitions to exhaustion, differed between groups. The whey group gained body weight (mean +4.7 lb, +2.11 kg) while the colostrum group gained bone-free lean body mass (mean +3.3 lb, +1.49 kg), a difference in composition without a difference in measured performance.
Who this may not transfer to:The trial enrolled both active men and women; it is small and single, so the body-composition signal in particular should not be over-read.
A single small trial with an active comparator. The lean-mass difference has not been reliably reproduced, and performance did not improve, so colostrum is not a supported ergogenic or muscle-building aid.
The study · 1
Antonio et al., The effects of bovine colostrum supplementation on body composition and exercise performance in active men and women · Nutrition 2001;17(3):243-247
What the Marketing Overclaims
The gap between the marketing and the trials is widest on three points:
- The growth-factor story. Colostrum contains IGF-1, and IGF-1 builds tissue, so the pitch is that swallowing colostrum floods you with anabolic hormone. The gut breaks that hormone down: a tracer study recovered only about 4% of ingested IGF-1 intact, and the body-composition trials show no muscle advantage over plain protein. Colostrum sold as a testosterone-adjacent muscle builder rests on absorption that does not happen.
- The cure-all framing. Colostrum is marketed at once for gut healing, immunity, skin, hair, energy, and anti-aging. The research covers two things: fewer sick days in hard trainers, and less exercise-related gut leakiness on lab tests. Skin, hair, general energy, and anti-aging rest on little direct human data.
- The strength of the base. The trials are small, several were run with supplement-industry involvement, and the pooled respiratory finding rests on studies the reviewers rated at moderate to high risk of bias. That does not erase the signal, and it sets the ceiling on how confidently anyone can sell it. Colostrum is also one of the more expensive supplements on the shelf, so you pay a premium for a modest, uncertain benefit.
How It Works
The usual account of colostrum is that it gives an adult the same compounds a calf gets: antibodies to fight infection, lactoferrin to bind iron away from bacteria, and growth factors to build tissue. Those compounds are in the product. The gap is between having them in the powder and having them act in an adult who swallows them, because most are proteins and the adult gut digests proteins. The effects that hold up are the ones that can happen in the gut itself, before digestion is complete. The claims that depend on these compounds reaching the bloodstream intact are the ones the trials do not support.
Anatomy of the Practice
1In the gut, first pass
Colostrum reaches the stomach and small intestine, where its proteins meet digestive enzymes. Immunoglobulins and growth factors are proteins, so most are broken into fragments and amino acids like any other protein. Some immunoglobulin and lactoferrin activity survives locally in the gut, which is the most plausible route for any effect.
2At the gut lining
Lactoferrin and growth factors acting on the gut wall itself are the mechanism behind the permeability findings. In small athlete trials, colostrum reduced the leakiness heavy exercise induces in the intestinal barrier. This is a local effect at the tissue colostrum reaches first, acting in the gut and not as a hormone in the blood.
3Beyond the gut
The pitch that colostrum raises circulating growth factors or delivers antibodies into the bloodstream is where the trials stop supporting it. Tracer work shows most ingested IGF-1 is digested, and any rise in blood IGF-1 in the training studies was modest and never tied to muscle growth. The reach of colostrum is mostly the gut and its immune tissue.
Go Deeper
- Protein and muscle: what actually builds muscle, and why total protein plus training outrank any colostrum-specific growth claim.
- Whey versus whole food protein: the comparator used in most colostrum trials, and the better frame for the muscle question.
- Whole foods: the cheaper foundation for most of what people hope colostrum does for immunity and the gut.
- Probiotics: the other heavily marketed gut supplement, and a useful check on how much of a gut claim the trials support.
- IBS: where gut-barrier ideas meet a defined condition, and what the evidence says about treating it.
The Chinese Medicine View
Chinese medicine has no concept of bovine colostrum or of immunoglobulins, and it would be an invention to claim otherwise. Colostrum is a modern product. What the tradition has is a long reading of milk and of rich, nourishing animal foods, and that lens can be laid over the supplement as one way of thinking, held apart from the trial data above.
Cow milk is classed in the tradition as sweet and neutral to slightly cooling, a substance that tonifies Qi and Blood, nourishes Yin, and moistens dryness. Foods of this kind are read as enriching, useful for someone depleted, dry, or worn thin, and burdening for someone who already tends toward dampness or phlegm, where a rich, moistening food is understood to feed the accumulation instead of nourishing the person. A concentrated first milk would be read as more of this quality, not less. The tradition does not treat a rich tonic as right for everyone; it matches the food to the person's constitution.
The two views touch without merging at what Chinese medicine calls the Spleen and Stomach. Chinese medicine holds that heavy, rich, dairy foods can burden a weak digestion and generate dampness, showing as bloating, loose stools, or a coated tongue, and it would caution a damp or phlegm-prone person against a steady intake of a rich milk product. That reading, where a nourishing food helps the depleted and burdens the congested, sits beside a modern finding that the clearest effect is local to the gut and depends on who takes it and why. It is offered as a way of thinking, not a claim about the compounds.
Cautions For This Practice
Extra restraintEverything to be aware of is here, in one place. This practice suits most healthy people; a few situations call for real care.
Dairy allergy
Bovine colostrum is a milk product and carries milk proteins, including casein and whey proteins. If you have a cow milk allergy it is not safe to take, and a severe milk allergy can produce a serious reaction. This is the clearest reason to avoid it, and it is separate from lactose intolerance.
Lactose intolerance
Colostrum contains some lactose, less than mature milk but enough to cause bloating, gas, or loose stools in people who do not tolerate lactose well. If you are lactose intolerant, start low or choose a different option, and stop if it causes gut symptoms.
Sourcing and quality vary
Colostrum is a collected animal product, so quality depends on the herd, the collection, and the processing. Products vary in how much active immunoglobulin they contain and in whether they are tested for contaminants. Favor a supplier that pasteurizes, discloses IgG content, and provides third-party testing, and be wary of unusually cheap products making large claims.
It is an animal product
Colostrum is taken from dairy cows, so it does not suit a vegan diet, and some readers will have concerns about collecting the early milk a calf would otherwise receive. Weigh that before choosing it over a plant-based alternative.
Not a substitute for vaccination or medical care
Colostrum is a supplement, not a treatment. It does not replace vaccines, and it is not a therapy for a diagnosed infection or gut disease. The trials were in healthy, mostly athletic adults, so if you are pregnant, immunocompromised, or unwell, raise it with your clinician before starting.
Athletes should check anti-doping status
Colostrum contains growth factors, including IGF-1, and some anti-doping authorities advise against it because of that content and the difficulty of ruling out banned substances in a natural product. If you compete under an anti-doping code, check the current guidance for your sport before using it.
Start slow, be smart, read the research, and consult a professional if you have any concerns. This is here to inform your choice, not make it for you.
Common Questions
Does bovine colostrum actually boost your immune system?
The one immune finding with trial support behind it is narrow: in people who train hard, colostrum reduced upper respiratory infection days by about 44% and episodes by about 38% across five small trials over eight to twelve weeks. Those trials were small and mostly rated at risk of bias, so the signal is promising and not yet settled. The broader claim that colostrum boosts general immunity in the average person is not backed by direct trials, and the rise in salivary IgA seen in some studies has not been tied to fewer infections outside the exercise setting.
Will colostrum build muscle or raise my IGF-1?
Swallowed IGF-1 is broken down in the gut, so it does not act as the anabolic hormone the marketing implies. A tracer study recovered only about 4% of ingested IGF-1 intact. The body-composition trials are small, use an active whey-protein comparator, and show no advantage in strength or endurance over plain protein. For muscle, total protein and resistance training are what the evidence points to.
Is colostrum good for gut health or leaky gut?
There is a specific, limited finding: in athletes, colostrum reduced the rise in gut permeability that heavy endurance exercise causes, measured by sugar-absorption tests and stool zonulin. These are surrogate markers in small trials, not symptom or disease outcomes. Across gastrointestinal conditions more broadly, the trials conflict and are too varied to pool, so colostrum is not established as a treatment for a diagnosed gut disease. For everyday gut complaints the case is thin.
How much do you take, and is it safe?
The upper respiratory trials mostly used around 10 to 20 g a day of colostrum powder during a hard training block; some gut-permeability work used far less, from about 500 mg. It is generally well tolerated in healthy adults, with mild digestive upset the most common complaint. The main limits are that it is a dairy product: it is unsafe with a cow milk allergy, can cause symptoms in lactose intolerance, and is not a vegan option. Quality varies, so favor a pasteurized product that discloses IgG content and is third-party tested.
Is it worth the money?
For most people, the case is narrow. If your goal is fewer sick days through a heavy training block, that is the one reason with trial support behind it, and the trial doses are the guide. For general wellness, sleep, enough total protein, and training you recover from do more for the same money, and colostrum is one of the pricier supplements on the shelf. It is a reasonable thing to try for a specific purpose, and an expensive way to chase the broad promises the marketing makes.
Explore Related
Other pages this one connects to, by the evidence they share, the outcomes they touch, and the ground they cover.
All 12 sources on this page independently checked and cross-referenced.
Thomas Dehli, Founder & Editor, Sacred Lotus
Sacred Lotus has published Chinese medicine reference material since 2001. Integrative pages are held to the same standard as the herb and formula library: cite the source, grade the claim at its real strength, and say where the research has not looked. This page is educational and it is not medical advice. Last reviewed and updated August 9, 2026.
Evidence strength
How confidently the research supports a claim. Strength describes the evidence, not our endorsement.