Colostrum is the nutrient-dense milk secreted by mammals (typically cows) in the first few days after birth. It is rich in antibodies, growth factors, and other bioactive compounds, and has been studied as a dietary supplement for immune function, athletic performance, and gut health. However, the evidence supporting many popular claims remains preliminary, and the supplement market is largely unregulated. This guide reviews the mechanisms, current research, safety profile, and practical considerations for using a colostrum supplement.

What Colostrum Is and How It Works

Colostrum is a milk precursor that differs markedly from mature milk in composition. It is higher in protein, immunoglobulins (especially IgG and IgA), lactoferrin, peptides, and growth factors including insulin-like growth factor-1 (IGF-1) and transforming growth factor-beta (TGF-β). These compounds are thought to pass through the digestive tract and exert local and systemic effects, though the extent of absorption and intact bioavailability remains contested.

The proposed mechanism involves reinforcement of the intestinal epithelial barrier, reduced intestinal permeability (often called