Warning! I had taken 50,000 I.U. of D2 and Calcium 1,800 mg daily because of hypothyroidism until I die. I appreciate D3 because it's cheaper than D2 and no need prescription. Iwas happy. But I became seriously ill after taking D3 instead of D2 for six months. Blood test showed that I had too much Calcium and it affected Kidney. Now, by the result of a few blood tests, I'm taking 4,000 I.U. D3 (not 50,000 I.U.) daily and recovered. Be careful! D3 might have stronger effect than D2. Even my doctor didn't know about that six months ago. When you try this one, you need to check your Calcium level at least after three months