What the science says about colostrum and athletic endurance

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There is a particular kind of frustration that comes with training consistently — eating well, sleeping adequately, doing everything right — and still feeling like recovery is lagging. Legs that don’t fully come back between sessions. A cold that arrives precisely at the worst moment in your training block. Gut discomfort during long efforts. These are common experiences among people who exercise regularly, and they are, in many cases, connected by a single physiological thread: the demands that sustained training places on the body’s inner ecosystem.

Bovine colostrum — the nutrient-dense first milk produced by cows in the 72 hours after calving — has been investigated as a nutritional support for athletes for over two decades. The research, while still evolving, points to several specific mechanisms through which it may help the body handle the demands of regular training more effectively. What follows is an honest look at what the evidence actually shows.

What colostrum contains — and why it matters for active people

Bovine colostrum is compositionally distinct from ordinary milk. It contains approximately five times the protein content, up to 300 times the concentration of immunoglobulins (primarily IgG, IgA, and IgM), and up to 250 times the lactoferrin of mature milk. It also contains a range of growth factors — including insulin-like growth factor 1 (IGF-1), transforming growth factor beta (TGF-β), and epidermal growth factor (EGF) — alongside proline-rich polypeptides (PRPs) that modulate immune function.

This combination is relevant for athletes for three interconnected reasons: the immunoglobulins support mucosal immune defence; the lactoferrin contributes to gut barrier integrity and iron transport; and the growth factors support tissue repair and adaptation. Each of these addresses a specific vulnerability that emerges under sustained training load.

Aerobic capacity: what a 12-week RCT found

The most directly relevant recent trial was published in the European Journal of Sport Science in 2025 (Durkalec-Michalski et al.). This was a randomised, double-blind, placebo-controlled crossover study — the gold standard of supplementation research — involving 28 endurance-trained males (triathletes and swimmers) who supplemented with 25 g of colostrum daily for 12 weeks alongside their usual training.

The primary finding was a significant increase in time to ventilatory threshold (TVT) in the colostrum group compared to placebo. The ventilatory threshold is the exercise intensity at which breathing effort escalates sharply — it is a key determinant of endurance performance, as working below it is sustainable for extended periods, while crossing it accelerates fatigue. The colostrum group also showed meaningful improvements in oxygen uptake at ventilatory threshold (VO₂VT) in both absolute and relative terms, and in power output at ventilatory threshold. Body composition was unchanged — this is not a supplement that inflates lean mass artificially. Read the full study.

The authors concluded that colostrum supplementation may be considered as a support for aerobic fitness in endurance-trained athletes, with the caveat that supplementation strategy should be personalised and integrated into individual training cycles.

The gut-exercise connection: a problem most athletes don’t know they have

Hard exercise is genuinely stressful to the gut. Blood is diverted from the gastrointestinal tract towards working muscles during sustained effort, which temporarily compromises the integrity of the intestinal lining. This leads to a measurable, transient increase in intestinal permeability — what is colloquially described as exercise-induced leaky gut.

A 2022 systematic review published in Nutrients synthesised the available evidence and confirmed that vigorous exercise consistently and significantly increases intestinal permeability — and that bovine colostrum supplementation helps to reverse this, supporting gut barrier function in trained athletes. The mechanism appears to be primarily through the action of lactoferrin and immunoglobulins on tight junction proteins in the intestinal epithelium. Read the full systematic review.

An earlier study published in the American Journal of Physiology (Playford et al.) demonstrated that bovine colostrum specifically truncated the increase in gut permeability caused by heavy exercise in healthy volunteers — an effect not seen with whey protein. Read the full study.

Why does exercise-induced gut permeability matter? Because when the intestinal barrier is compromised, bacterial fragments and luminal toxins can enter systemic circulation, triggering immune activation and inflammation. For athletes training frequently, this is a repeating cycle — and one that may contribute to the chronic low-grade inflammation, suppressed immunity, and impaired recovery that characterise overreaching.

Immune resilience during training blocks

The relationship between intense exercise and immune function follows a well-established pattern: moderate regular exercise supports immune health, while very high training loads temporarily suppress it — particularly mucosal immunity (secretory IgA in saliva and the gut). This is the window in which athletes are most vulnerable to upper respiratory infections.

Colostrum’s immunoglobulin content — particularly secretory IgA — helps maintain mucosal immune competence during periods of elevated training stress. A 2021 review in Nutrients (Davison) summarised the evidence across multiple trials and found consistent signals of maintained or improved immune markers in athletes supplementing with bovine colostrum, including fewer upper respiratory illness episodes in some cohorts. Read the full review.

Admittedly, the immune research is not uniformly positive — effect sizes vary by population, training load, and study design. But the mechanistic rationale is sound, and the safety profile of bovine colostrum is well-established across the available literature.

Where Bio-Avail Colostrum+ fits

Adapt Naturals’ Bio-Avail Colostrum+ is formulated as a triple-action supplement that goes beyond standard colostrum products by combining three complementary ingredients:

• Bovine colostrum — sourced from pasture-raised cows, standardised for immunoglobulin and growth factor content. This is the primary active ingredient with the bulk of the clinical evidence behind it.
• Lactoferrin — a glycoprotein naturally concentrated in colostrum but often present at lower levels in standard colostrum supplements. Lactoferrin has specific evidence for supporting gut epithelial tight junctions and for its antimicrobial and iron-transport properties.
• Beta-glucan — a soluble fibre derived from oats or yeast that acts as a prebiotic and helps prime innate immune responses via interaction with pattern-recognition receptors on immune cells.

The combination is designed to address gut barrier integrity, mucosal immune competence, and systemic immune priming through distinct but complementary mechanisms — rather than relying on a single ingredient at high dose. For people with a meaningful training load, or who find that hard training blocks reliably bring on illness or digestive difficulty, this kind of targeted support is worth considering.

Practical considerations

A few things worth knowing before starting colostrum supplementation:

• Timeframe. The trial showing aerobic capacity benefits used 12 weeks of supplementation. This is not a supplement where you’ll notice something in a week. The research consistently suggests that meaningful physiological adaptation requires several months of consistent use.
• Dairy sensitivity. Bovine colostrum is a dairy product. People with a confirmed dairy allergy (as opposed to lactose intolerance, which is different) should approach with caution and speak to a GP or registered dietitian first.
• IGF-1 and sport regulations. The World Anti-Doping Agency has previously noted colostrum as a substance of concern due to its IGF-1 content, though it is not currently on the prohibited list. Competitive athletes who are subject to anti-doping regulation should check their sport’s specific rules before use.
• Consistency over volume. The evidence points towards moderate daily doses (20–25 g) taken consistently, rather than high doses around training sessions. Anchoring it to a meal, as with any daily supplement, is the most reliable way to build the habit.

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This article is for educational purposes and isn’t medical advice. Supplements aren’t a substitute for a varied diet or medical care. If you’re pregnant, breastfeeding, taking medication, or managing a health condition, speak to your GP or a registered professional before starting anything new.