Vitamin D3

Vitamin D3 is supplied by BioLifeLab, sealed in a tamper-evident vial and stated at 99% purity on the label. It is supplied in a single 20,000 IU ampoule, so the size can be matched to how much material a study will consume before the vial is opened again. Store sealed vials between 2 and 8 °C in a cool, dry place away from direct sunlight; stability drops sharply once a peptide is reconstituted, so prepare only what a protocol needs.