Abstract: The present invention provides novel compositions comprising a nutritional supplement containing vitamin D-3 (cholecalciferol) and other supporting nutrients (i.e., fat-soluble vitamins A and E) to be administered orally via capsules to human subjects for the prophylaxis and mitigation of hair thinning and hair loss in both men and women. Colloidal silicon dioxide functions to form a nanoparticulate suspension and acts as a viscosifier to thicken the oil(s) used in the capsule filling operation. The colloidal silica contains silicon which acts as a nutrient to help strengthen existing hair, and also functions as a microencapsulation agent, which can incorporate vitamins A and E into its porous structure by sonication.