Background: Myo-inositol is a natural molecule with important therapeutic applications and
an impaired oral absorption may result in a reduced clinical effect. Aim of this study was to determine if
the combined oral administration of α-lactalbumin and myo-inositol in healthy subjects, could increase
the plasma level of myo-inositol administered alone. In vitro studies on human differentiated intestinal
Caco-2 cells were also conducted to identify the mechanisms involved in myo-inositol absorption.
Objective: The in vivo study was conducted on healthy volunteers in two phases. Subjects received a
single oral myo-inositol dose. After 7 days washout, the same subjects were administered a single dose
of myo-inositol and α-lactalbumin. Cmax, Tmax and AUC for myo-inositol in plasma were calculated
from samples collected at different times. Transepithelial myo-inositol passage, with or without addition
of digested α-lactalbumin, was measured in vitro in differentiated Caco-2 cells and compared to transepithelial
electrical resistance and phenol red passage.
Results: The bioavailability of myo-inositol was modified by the concomitant administration of α-
lactalbumin. Although peak concentration of myo-inositol at 180 min (Tmax) was similar for both
treatments, administration of α-lactalbumin with myo-inositol in a single dose, significantly increased
the plasma concentrations of myo-inositol compared to when administered alone. In vitro, myo-inositol
absorption in Caco-2 cells was improved in the presence of digested α-lactalbumin, and this change was
associated with an increase in tight junction permeability.
Conclusion: Better myo-inositol absorption when orally administered with α-lactalbumin can be beneficial
in non-responder patients. Preliminary in vitro findings suggest that peptides deriving from α-
lactalbumin digestion may modulate tight junction permeability allowing increased absorption of myoinositol.