Also known as: Bovine colostrum, First milk, IgG, Immunoglobulins, Lacteal secretion
FoundationalStrong evidence
The first milk produced after calving, rich in immunoglobulins and growth factors. Reasonable evidence for gut barrier and respiratory outcomes in athletes, though most retail products are dosed far below the research.
Typical dose
20.0–60.0 g per day
Daily, with cool or room-temperature liquid
What it is
Colostrum is the milk produced in the first day or two after a mammal gives birth. It differs substantially from ordinary milk, being far richer in immunoglobulins, growth factors and other bioactive proteins that prime a newborn's immune system and gut.
Supplements use bovine colostrum, collected as surplus after the calf has fed. Quality products are standardised to immunoglobulin G content, commonly 15 to 40 per cent.
Processing matters. Immunoglobulins are proteins and are destroyed by heat, so low-temperature processing is essential. A colostrum that has been aggressively heat-treated is expensive milk powder.
How it works
Colostrum acts largely within the gut rather than systemically. Immunoglobulins bind pathogens in the intestinal lumen, and growth factors support the integrity of the intestinal lining.
That local action is the key to understanding it. The proteins are not absorbed intact in meaningful quantity in adults, and they do not need to be for the gut barrier effect.
This matters for athletes because prolonged exercise, particularly in heat, transiently increases intestinal permeability. Supporting the barrier during that stress is the most mechanistically coherent use, rather than any systemic immune claim.
What the evidence shows
Intestinal permeability is the best-supported outcome. Several trials have reported reduced exercise-induced increases in gut permeability with colostrum supplementation, which is a measurable and consistent finding.
Research on upper respiratory symptoms in athletes during heavy training has generally been favourable, with reported reductions in symptom days, though trial quality varies.
Evidence for performance, body composition or systemic growth factor effects is weak. The growth factor content is often used in marketing, but those proteins are digested rather than absorbed intact, and claims built on them do not hold up.
Dosing
This is where most products fall down. The trials showing effects used 20 to 60 g daily. A great many retail colostrum capsules supply 1 to 2 g, which is a tiny fraction of that.
If you are buying colostrum for the researched effects, you need a powder at a serious serving size, not a couple of capsules. Check grams per serving before anything else.
Take with water rather than a hot drink, since heat degrades the immunoglobulins. Effects on permeability have been reported over 14 days or more of consistent use. Standardised IgG content is the quality marker worth comparing.
Acts locally in the gut; effects accrue over 2 weeks or more
Timing
Daily, with cool or room-temperature liquid
Competition status
Permitted — not on the WADA Prohibited List, though some governing bodies have historically advised caution over growth factor content
Category
Foundational
Safety and side effects
Colostrum is a dairy product and is well tolerated by most people. Bloating and digestive discomfort are the usual complaints, particularly at the large doses the research used.
Milk allergen declaration is mandatory and anyone with a milk allergy must avoid it entirely. It also contains lactose, so those who struggle with dairy sugar may react at higher doses.
Sourcing is worth attention: animal welfare standards vary, and the calf's own requirement should come first. Ask suppliers about their collection practices.
Who should avoid it
Milk allergen declaration applies; avoid entirely with a milk allergy. Contains lactose. Not suitable for vegans. Speak to your doctor before use if your immune system is being managed or if you take regular medication. Ask suppliers about welfare standards and collection practices.
This entry is provided for information only. Food supplements should not be used as a substitute for a varied and balanced diet and a healthy lifestyle. Consult a qualified healthcare professional before use if you are pregnant, breastfeeding, taking medication or under medical supervision.
