Vitamin D: The Introduction 1-2

Introduction to Vitamin D - Part I-2

In some ways, it almost now seems a misnomer to describe vitamin D as a vitamin, its structure and function seem to have more in common with a steroid hormone. A steroid hormone which we can not manufacture, but which is so essential to good health that it is not merely obtained, in varying amounts through diet, but is also, the only essential molecule, produced in the skin through exposure to direct sunlight.

It will likely take quite some time to sort out the various effects and actions of vitamin D, and as with other scientific advances each new piece of knowledge will likely raise ten new questions. And it is important not to get carried away with new discoveries which have a way of often proving to be less important than first thought. However, these are undoubtedly important new findings and one of the first questions they bring to mind is what is the optimum level of vitamin D one should have for good health.

This question is currently an area of active debate, many physicians and scientists feel that the current guidelines, which were set to ensure healthy bones and good calcium metabolism, are not high enough to ensure proper immune function and to receive other health benefits from vitamin D. A related question involves the issue of the potential for toxicity from vitamin D. On the basis of very scant evidence, the value of which has been repeatedly challenged, a recommendation of no more than 2000 IU of vitamin D daily has been established. Without attempting to address this question in full in this post, one quite obvious argument against this position is that someone receiving 20-30 minutes of direct sunlight when sunbathing will produce some 10,000- 20,000 IU of vitamin D. This begs the question, unless one theorizes some yet undiscovered difference between dietary vitamin D and that produced in the skin from sunlight, why aren't lifeguards, for instance, showing hepatic calcifications and other signs of vitamin D toxicity when they are daily receiving a dose some 5-10x greater than the maximum safe dose. Instead, such individuals, are often the picture of health.

Even using the current guidelines for what constitutes vitamin D deficiency, one finds this to be an underdiagnosed and wide-spread problem, especially in the elderly. If as many physicians and scientists now feel, the guidelines for adequate vitamin D levels are too low than a very significant percentage of the population is vitamin D deficient and would benefit from either more sunlight or greater dietary intake of vitamin D. And there is reason, considering the changes brought about by modern life, for this to be a concern. People work outdoors far less than they used to in previous generations. Even in commuting back and forth to work they are usually in cars, buses or trains away from the sun, while recent concerns about skin cancer further incentivise people to avoid all direct exposure to sunlight. Finally, the diets of many people have changed radically with much more processed and less nutritious foods being consumed while more healthy foods including ones rich in vitamin D such as fish are often ignored.

Paul D Maher