The role of vitamin D has long been underestimated and only partially understood. We need to remember this fact. Our lives depend on the sun. Without it, there is no life. The sun provides vitamin D to our bodies and we are learning that vitamin D is involved in most of not all bodily functions. By its very nature of being a vitamin that is passively acquired by humans just by being outdoors, which is a natural state of man, vitamin D is essentially the most important of all nutrients. It is the one that is taken for granted by nature that we will have access to by exposure to the sun. With modern lifestyles, we foil the very purpose of the relationship between the sun and life, and must make constant efforts to replace this all-important vitamin that most of us are not getting in adequate amounts. When we think about it, it seems a no-brainer that the nutrient provided by the sun itself would be the most important but it has taken science a very long time to move towards this realization. Rather than continue to wait for each new revelation about vitamin D one by one, we need to be proactive and make sure that we are getting a sufficient supply, either by regular exposure to the sun or by taking good supplements of D.
My own experience has shown me that vitamin D deficiency is rapidly corrected and that dramatic effects can be seen in a very short time. In my case, doubling my dosage relieved muscle pain and tired legs within two weeks. Forgetting to take my normal dose quickly brings back the sore muscles. My next long trip will involve experimenting with vitamin D to see if it helps with the jet lag that makes travel such an ordeal for me.