High-dose vitamin D supplementation reduces disease activity in clinically isolated syndrome typical of MS, results of a ...

The maximum dosage to take per day should be 4,000 units, says Dr. Peterson. But chat with your doctor at your annual physical after looking at your current vitamin D levels before adding this ...

This means that your body uses vitamin D3 more efficiently, so you might need a higher dose of vitamin D2 to achieve the same effects as you might with a supplement that includes just D3.