 Introduction
WHAT IS VITAMIN D?
Vitamin D is a hormone, not a vitamin. It is synthesized in the skin and then converted to its stored active form by the liver.
SUNLIGHT PROVIDES ENERGY FOR CHANGE IN MOLECULAR STRUCTURE AND OPENS THE RING STRUCTURE OF THE IMMEDIATE PRECURSOR TO CHOLESTEROL.
A single gel cap of Maximum D3® contains approximately the same amount - of the same human hormone - a light skinned person would make if exposed to summer sun for a few hours.
Excellent introductions to the chemistry and actions of vitamin D and other hormones can be found at:
Vitamin
D
(Thank you Colorado State )
http://vitamind.ucr.edu/about.html
(
UC Riverside)
WHAT DOES VITAMIN D DO?
Vitamin D's actions are best understood in its role in calcium metabolism. Without it a person is not able to absorb the calcium in his or her diet or maintain the proper balance of calcium and phosphorus to support bone mineralization - build and maintain bones. Lack of vitamin D can also cause over stimulation of the parathyroid gland and muscle weakness.
Recent studies have found that vitamin D receptors are present in most if not all cells in the body. Experiments suggest that vitamin D has physiologic effects much broader than just a role in mineral homeostasis and bone function. This is an active area of research, but not well understood. This is an important point because there has been interest in vitamin D and several cancers, menopause, and effects on other organs. These are areas of ongoing research.
ARE THERE NATURAL SOURCES FOR VITAMIN D?
Yes, but dietary sources are rarely adequate. The principal natural source of vitamin D is sunlight. Exposure of the entire body to sunlight to the point of mild redness will raise the blood level of vitamin D about as much as 20,000 IU of D3. It has been estimated that full summer sun exposure of the neck, back and arms for 15 minutes twice a week will provide adequate vitamin D levels in young adults. Sun effect depends on season and distance from the equator, age and pigmentation of the skin.
Some fish oils are fair sources of vitamin D. A tablespoon of cod liver oil a day should do the trick, but this amount presents the problem of too much vitamin A.
MORE IS NOT BETTER!
As has already been stated, vitamin D is a hormone and has receptor sites throughout the body. TOO MUCH CAN BE HARMFUL. The approximate desirable blood levels and doses needed for bone health are still under discussion and for other tissues not yet established or well understood. (Most positions are divided between minimal needed for overt bone disease and upper normal observations in sun exposed populations.) MAXIMUM D3 was designed to meet the demonstrated needs in normal persons and still provide a substantial safety margin if other sources of vitamin D are consumed.
|
