The term Microlactin appears to refer to an extract derived from Milk protein from hyperimmunized cows, particularly the bioactive peptides. Microlactin is also sometimes referred to as Hyperimmune milk, and appears to be obtained via delivering an immune stimulant (Polyvalent immunization of bacteria derived from the human gut) to pregant cows 4 weeks before parturition and continuing every 2 weeks through lactation, and was discovered in 1955 when application of a human pathogenic bacteria produced a high degree of antigen-specific antibodies milk secretions.
Microlactin (Hyperimmune milk) is milk derived from cows that, prior to lactation, are delivered an immunostimulant and subsequently produce more bioactive peptides in the milk they produce
Microlactin contains both high weight and low weight bioactive peptides, with the high weight peptides being antigen-specific peptides while the lower weight peptides confer general anti-inflammatory properties. For the high weight bioactive peptides, the immunoglobulin IgG appears to be predominant in most milk whereas the IgG type I antibody appears to be 20-40% higher in Hyperimmune milk relative to normal skim milk although another study quantified the dose at 5.45mg/g (5.11-5.79mg/g) in Hyperimmune milk while failing to detect any in control (skim) milk (did not disclose limit of quantification).
It should be noted that the high molecular weight antibodies are detectable in normal cow milk as well as hyperimmune milk, although at lower quantities (with this study noting that the greatest difference was in the antibody for Pseudomonas aeruginosa with Hyperimmune having 282% more antibody activity in vitro).
Microlactin appears to be standard milk protein concentration but with a higher concentrations of Immunoglobulin G (IgG) relative to standard milk protein concentrates; for all intents and purposes, bioactivity that differs between Microlactin and regular milk is probably due to the IgG content
When looking at the IgG bioactive peptide, it has been noted to resist acid hydrolysis in the stomach during digestion in infants and in human adults following oral administration when paired with antacids (sometimes called buffered immunoglobulins).
In persons with high cholesterol (n=11 and no placebo group), Hyperimmune milk at 45g (Skim milk, rather than isolated protein) has been noted to reduce circulating cholesterol. This trial used a crossover design using either 8 weeks of Hyperimmune milk followed by regular skim milk or vice versa, and in both conditions serum cholesterol was reduced during the Hyperimmune period but not skim milk period; cessation of milk products saw normalization of serum cholesterol. A later study doubling the dose quantified the reduction of LDL-C (5.2%) and Total cholesterol (7.4%) in a similar cohort of hypercholesterolemic persons against a placebo of regular skim milk; this study failed to find an influence on triglycerides or HDL-C, and noted that both systolic (2.3%) and diastolic (3.9%) blood pressure were reduced relative to placebo.
One intervention has been conducted (independently) in persons with minor pain associated with osteoarthritis of the knee given a test beverage containing 9g of Microlactin (with some sugar and compared to a sugar placebo) and assessed by the Western Ontario MacMaster Universities Osteoarthritis Index (WOMAC) derived from the Knee Injury and Osteoarthritis Outcome Score (KOOS) noted that weeks 3-6 of supplementation were associated with an improvement in the WOMAC osteoarthritic index relative to baseline while placebo was not.
Another study using reconstituted hyperimmune milk protein at 2000mg twice daily (4000mg daily) in persons with knee osteoarthritis with Glucosamine sulfate at 1,500mg as active control noted that over 6 weeks usage of Microlactin improved symptoms scores as assessed by WOMAC (on all measured subsets of pain, stiffness, activity, and total) while Glucosamine outperformed placebo on stiffness and total. Microlactin slightly outperformed Glucosamine on all parameters but none appeared to be statistically significant.