In December by chance I put a pack of Vitamin D into my shopping basket. I did not think much, thought to take 1000IE but then decided that for the first week I take 3000 to catch up. Muscle pain went and control over eating improved. I did not expect any changes based on past experience with 1000 but this time I could not ignore it (age can play a role) and I stayed on 3000. Tests a month later showed I was just not deficient any-more. I continued on the regime and started having improvements in long running skin issues to the extent my dentist noticed. It may not be a miracle drug but one should not underestimate cumulative impact individual factors, age and lifestyle changes (less sun) that may change levels and demand.