Recent studies have shown that vitamin D3 is a more potent form of vitamin D. Vitamin D2 has a shorter shelf life, and its metabolites bind with protein poorly, making it less effective. One unit of cod liver oil (containing vitamin D3) has been shown to be as effective as four units of Viosterol (a medicinal preparation of vitamin D2).
Excerpt taken from Mercola.com
Use caution when purchasing any supplement as you may be wasting your valuable money. Please do not hesitate to contact our holistic doctor Patrick “Skip” Hart for help with your supplement selection.