Quick Answer: Bovine colostrum is the first milk cows make after giving birth, dried into a powder or capsule. The best evidence is in adults doing regular hard exercise: a 2016 meta-analysis of 5 small trials found 44% fewer days with cold-like upper respiratory symptoms, though most trials had moderate or high risk of bias. Small trials also suggest it can limit rises in gut permeability during intense exercise or NSAID use. For muscle, it performs about like other milk proteins such as whey. Claims about general immunity, “leaky gut” symptoms, skin, hair or weight loss in healthy people are not established. It is a dairy product, so people with a milk allergy should avoid it, and it should not be given to babies or children without a pediatrician’s advice.
Colostrum Claims vs the Evidence at a Glance
| Claim | What the research shows | Strength of evidence |
|---|---|---|
| Fewer colds and sore throats | 5 RCTs, 152 exercising adults: 44% fewer symptom days, 38% fewer episodes (Jones 2016) | Low to moderate; small, mostly biased trials; athletes only |
| “Boosts immunity” (immune markers) | 10 RCTs, 239 active adults: no or fairly low effect on blood IgA, IgG, lymphocytes, neutrophils or saliva IgA (Główka 2020) | Moderate that markers change little |
| Gut permeability (“leaky gut”) | Meta-analysis of 10 studies: lower lactulose/rhamnose ratio, but very high variation between studies (Hajihashemi 2024) | Low; small trials, lab marker only |
| Childhood infectious diarrhea | 5 RCTs: fewer stools per day and less diarrhea (Li 2019); later review of 8 studies called benefits inconclusive (Oswal 2025) | Low and conflicting |
| Preterm infants | 4 RCTs, 670 infants: authors say it cannot be recommended (Yao 2026) | Not recommended |
| Muscle and strength | Similar to whey in most head-to-head trials; grouped with milk proteins as effective in a 116-trial network meta-analysis (Zhou 2023) | Moderate, as a protein source |
| Skin, hair, weight loss, energy | No meaningful clinical trial evidence found in our review | Not established |
Study details are from the PubMed abstracts listed in Sources. “Strength of evidence” is our editorial summary of study size, design and consistency, not a formal grading.
What Is Colostrum?
Colostrum is the milk mammals produce in the first few days after birth. A 2021 review in Nutrients describes it as containing high levels of immunoglobulins (antibodies), antimicrobial peptides and growth factors that support a newborn’s growth and immune defense; other researchers also highlight lactoferrin. Colostrum supplements are made from bovine (cow) colostrum, usually collected from dairy farms, then pasteurized or processed and spray-dried into powder or capsules.
The idea behind supplementing is that some of these proteins survive digestion and act locally in the gut. That is plausible, and it is why most of the better studies measure gut-related outcomes. It does not mean an adult gets the same benefits a newborn calf does. One caveat worth knowing: the authors of that 2021 review work for a company that supplies bovine colostrum, a conflict of interest they disclosed.
Colostrum for Colds and Immunity
Upper respiratory symptoms in people who exercise
This is the strongest-looking result. A 2016 systematic review and meta-analysis in BMC Sports Science, Medicine and Rehabilitation pooled 5 randomized trials with 152 adults in regular exercise training. Over 8 to 12 weeks, colostrum compared with placebo reduced the rate of upper respiratory symptom days by 44% (rate ratio 0.56) and symptom episodes by 38% (rate ratio 0.62).
The authors were cautious, and so are we. Because of incomplete reporting, 4 of the 5 trials were judged to have a moderate or high risk of bias, the individual estimates were imprecise, and they called for a larger, well-designed trial. The participants were all exercising adults, so the result does not tell us about sedentary people, older adults or children.
Immune markers barely move
If colostrum “boosted” the immune system in a general sense, you would expect blood and saliva antibody levels to rise. A 2020 meta-analysis in Nutrients of 10 randomized trials with 239 athletes and active adults found that colostrum had no or a fairly low impact on serum IgA and IgG, lymphocytes, neutrophils and salivary IgA. The authors noted that earlier research suggested fewer respiratory infections, but that how this might happen is unknown.
Colostrum and Gut Permeability (“Leaky Gut”)
Intestinal permeability is measured in studies by having people drink two sugars, such as lactulose and rhamnose or mannitol, and comparing how much of each shows up in urine. A higher ratio suggests a “leakier” gut lining. Several small trials have tested colostrum this way:
- NSAIDs: In a 2001 crossover trial in 7 healthy men, 5 days of the NSAID indomethacin caused a 3-fold increase in gut permeability when taken with whey protein, but no significant increase when taken with colostrum. In 15 patients already on long-term NSAIDs, colostrum made no difference (Playford 2001).
- Heavy exercise: In a 2011 double-blind crossover trial in 12 volunteers, permeability rose 2.5-fold after standardized exercise on placebo, while 14 days of colostrum cut that rise by 80% (Marchbank 2011).
- Athletes in training: In 16 athletes during peak training, 20 days of 500 mg colostrum lowered permeability test values and stool zonulin compared with a whey placebo (Hałasa 2017).
A 2024 meta-analysis in Digestive Diseases and Sciences pooled 10 studies and found a significant reduction in the lactulose/rhamnose ratio, but heterogeneity was extremely high (I² = 99%), and there was no difference in plasma I-FABP, a marker of gut cell damage. The authors said more trials with consistent quality, dose and duration are needed. Importantly, none of these studies show that colostrum relieves bloating, fatigue or other symptoms often blamed on “leaky gut.” See our leaky gut guide for the broader picture.
Colostrum for Diarrhea in Children
A 2019 meta-analysis in Scientific Reports included 5 randomized trials and found that bovine colostrum products reduced stool frequency in childhood infectious diarrhea by about 1.42 stools per day and lowered the odds of diarrhea by 71% (odds ratio 0.29). But a 2025 systematic review in the Journal of Pediatric Gastroenterology and Nutrition that looked at 8 studies concluded that “no conclusion can be drawn” about colostrum’s clinical benefits for children’s gut health, because the studies differed too much in dose, product and outcomes.
For preterm babies, a 2026 meta-analysis of 4 trials with 670 infants found a lower rate of feeding intolerance, but attributed it likely to lack of blinding, found no benefit for necrotizing enterocolitis or time to full feeds, and concluded colostrum cannot be recommended for preterm infants. Supplements sold to adults are not a substitute for breast milk or infant formula. For diarrhea in a child, oral rehydration and a call to the pediatrician come first.
Colostrum vs Whey Protein for Muscle
Colostrum is mostly protein, so it is natural to compare it with whey. The head-to-head trials show more similarity than difference:
- Active adults, 8 weeks, 20 g a day: the colostrum group gained 1.49 kg of lean mass, while the whey group gained 2.11 kg of body weight; there were no differences in strength or endurance tests (Antonio 2001).
- Older adults, 8 weeks, 60 g a day with resistance training: colostrum increased leg-press strength more than whey (24 kg vs 8 kg) and reduced a bone-breakdown marker, but bench press, muscle thickness and lean mass improved similarly in both groups (Duff 2014).
- Trained lifters, 12 weeks, 60 g a day: strength, endurance and sprint capacity rose equally in all groups (Kerksick 2007).
A 2023 network meta-analysis of 116 trials with 4,711 participants grouped bovine colostrum with milk, whey, casein and yogurt as “milk proteins” that were effective for gains in muscle mass and strength. In plain terms, colostrum works as a protein source, but there is no strong evidence it beats ordinary whey. For protein choices, see whey vs casein.
Side Effects, Allergies and Who Should Avoid It
In the trials above, colostrum was generally reported as well tolerated, but most lasted only weeks and enrolled healthy adults. Practical cautions:
- Milk allergy: colostrum is a cow’s milk product. Milk is one of the nine major food allergens identified by U.S. law, per FDA. Avoid colostrum if you have a milk allergy.
- Lactose intolerance: colostrum contains milk sugar. Check the label, and start low if you are sensitive.
- Pregnancy and breastfeeding: there are no good safety data; ask your clinician first.
- Babies and children: do not give colostrum supplements without a pediatrician’s advice (see above).
- Competitive athletes: colostrum naturally contains growth factors. Choose a product with a sport-specific third-party certification if you are drug-tested.
FDA does not approve dietary supplements for safety and effectiveness before they are sold; manufacturers are responsible for evaluating the safety and labeling of their products. The NIH Office of Dietary Supplements notes that independent organizations such as ConsumerLab.com, NSF International and U.S. Pharmacopeia offer quality testing; their seals indicate a product was properly manufactured, contains the listed ingredients and lacks harmful levels of contaminants, but do not guarantee it is safe or effective.
How Much Colostrum Did Studies Use?
There is no established dose. Amounts in the trials cited on this page ranged from 500 mg a day (Hałasa 2017) to 20 g a day (Antonio 2001) and 60 g a day (Duff 2014; Kerksick 2007), usually for 2 to 12 weeks. Products also differ in how they are processed and in their stated immunoglobulin content, so results from one study may not apply to the product you buy. Follow the label, and do not assume more is better.
Who Should Choose What
- Endurance or team-sport athlete prone to colds in heavy training: colostrum has the most supportive (if imperfect) data for you. Treat it as an experiment, not a sure thing, and talk with a sports dietitian.
- Want more protein for muscle: whey or other milk proteins are better studied, and colostrum offers no clear advantage.
- Gut symptoms such as bloating or irregularity: colostrum is unproven for symptoms. Fiber, probiotics with strain-specific evidence and a medical evaluation are better starting points; compare L-glutamine vs probiotics and probiotics vs prebiotics.
- Hoping for better skin, hair or weight loss: we found no meaningful clinical evidence for these claims.
- Milk allergy, pregnant, or buying for a child: skip it unless your clinician advises otherwise.
How to Read a Colostrum Label
- Check the amount per serving in milligrams or grams, and compare it with the study doses above.
- Look for a stated immunoglobulin (IgG) percentage and whether the company says how it was tested.
- Read the allergen statement. It should declare milk.
- Look for a named third-party seal (USP, NSF or similar) rather than vague “lab tested” wording.
- Be skeptical of disease claims. Supplements cannot legally claim to treat or cure a disease.
When to Talk to Your Doctor or Pharmacist
Talk with a clinician before using colostrum if you are pregnant or breastfeeding, have a milk allergy, have a chronic gut condition such as inflammatory bowel disease, have a weakened immune system, or take prescription medicines. Get medical care for diarrhea that is bloody, lasts more than a couple of days, or comes with signs of dehydration, especially in a child.
Frequently Asked Questions
What is bovine colostrum?
Colostrum is the first milk a cow produces in the days after giving birth. It is richer than regular milk in immunoglobulins (antibodies), antimicrobial proteins such as lactoferrin, and growth factors. Supplements are usually dried, powdered bovine colostrum.
Does colostrum boost the immune system?
Evidence is mixed. A 2016 meta-analysis of 5 trials (152 exercising adults) found 44% fewer days with upper respiratory symptoms, but most trials had moderate or high risk of bias. A 2020 meta-analysis of 10 trials found little or no effect on blood or saliva immune markers.
Does colostrum help leaky gut?
Small trials suggest it may limit rises in gut permeability during heavy exercise or NSAID use, and a 2024 meta-analysis of 10 studies found a reduction in a permeability test ratio. The studies were small, results varied widely, and they measured a lab test rather than symptoms.
Is colostrum better than whey protein?
For muscle, not clearly. In trials comparing them during resistance training, colostrum and whey produced similar gains in most measures. A 2023 network meta-analysis grouped colostrum with other milk proteins as effective for muscle mass and strength.
What are the side effects of colostrum?
Trials have generally reported it as well tolerated. Because it is a milk product, it is not suitable for people with a cow's milk allergy and may cause symptoms in people who are lactose intolerant. Supplements are not FDA-approved before sale.
Can children or babies take colostrum supplements?
Do not give colostrum supplements to infants or children without a pediatrician's advice. A 2025 systematic review called the evidence in children inconclusive, and a 2026 meta-analysis said bovine colostrum cannot be recommended for preterm infants.
How much colostrum should I take?
There is no established dose. Trials have used amounts ranging from 500 mg a day to 60 g a day. Follow the product label and ask a clinician before starting.
Sources
- Jones AW et al. Bovine colostrum supplementation and upper respiratory symptoms during exercise training: systematic review and meta-analysis. BMC Sports Sci Med Rehabil. 2016
- Główka N et al. Immunological outcomes of bovine colostrum supplementation in trained and physically active people: meta-analysis. Nutrients. 2020
- Hajihashemi P et al. Bovine colostrum in increased intestinal permeability: meta-analysis of randomized clinical trials. Dig Dis Sci. 2024
- Playford RJ et al. Bovine colostrum reduces the acute NSAID-induced increase in intestinal permeability. Clin Sci. 2001
- Marchbank T et al. Bovine colostrum truncates the increase in gut permeability caused by heavy exercise in athletes. Am J Physiol Gastrointest Liver Physiol. 2011
- Hałasa M et al. Oral supplementation with bovine colostrum decreases intestinal permeability and stool zonulin in athletes. Nutrients. 2017
- Li J et al. Bovine colostrum and product intervention associated with relief of childhood infectious diarrhea. Sci Rep. 2019
- Oswal D et al. Effect of bovine colostrum supplementation on gut health of children: a systematic review. J Pediatr Gastroenterol Nutr. 2025
- Yao J et al. Bovine colostrum in feeding intolerance in preterm neonates: systematic review and meta-analysis. Front Nutr. 2026
- Antonio J et al. Effects of bovine colostrum supplementation on body composition and exercise performance in active men and women. Nutrition. 2001
- Duff WR et al. The effect of bovine colostrum supplementation in older adults during resistance training. Int J Sport Nutr Exerc Metab. 2014
- Kerksick CM et al. Impact of differing protein sources and a creatine containing formula after 12 weeks of resistance training. Nutrition. 2007
- Zhou HH et al. Timing and types of protein supplementation in adults undergoing resistance training: network meta-analysis. Int J Sport Nutr Exerc Metab. 2023
- Playford RJ, Weiser MJ. Bovine colostrum: its constituents and uses. Nutrients. 2021
- FDA: Dietary supplements
- FDA: Food allergies (nine major food allergens)
- NIH Office of Dietary Supplements: Dietary supplements, what you need to know
Medical disclaimer: This article is for educational purposes and does not replace medical advice. Consult a licensed healthcare provider before starting any supplement, medication, or treatment — particularly if you are pregnant, breastfeeding, taking other medications, or have a diagnosed medical condition.