Page 30 - Summer 2017 Journal

Today even conventionally minded doctors are testing and prescrib- ing vitamin D supplements. Medicare experienced an 83-fold increase in vitamin D blood tests from 2000 to 2010, and commercial health insurers saw a 2.5-fold increase from 2009 to 2014.5 Having a robust vitamin D level has become akin to having a low cholesterol level, thought to be a marker of good health. Astute readers know that this modern-day quest for optimal health and longevity is fraught with risks.
As with any trend in medicine, many are now questioning the ben- efits of vitamin D testing. Medscape, an influential source for continuing medical education, recently advised doctors that vitamin D testing is both expensive and not fully reliable, encouraging supplements of 1,000 IU per day for adults as both safe and sufficient without the requirement for testing.6 Health insurers are asked to cover the fifty dollar cost of the test, which they state for most cases is not medically necessary; some are now denying reimbursement, which is not surprising since the Institute of Medicine stated in their 2010 report on vitamin D, “[T]he measure- ments, or cut-points, of sufficiency and deficiency used by laboratories to report results have not been set based on rigorous scientific studies, and no central authority has determined which cut-points to use.”7
TYPICAL TESTING AND SUPPLEMENTATION PROTOCOLS Vitamin D3 is the natural form synthesized in the skin upon expo- sure to UVB light, or consumed from animal-based foods; vitamin D2 is the artificial or plant-derived form often used in food fortification, supplements and pharmaceutical preparations. (See sidebar on page 32 for differences between vitamin D2 and D3, and problems with vitamin D supplements.) Both of these forms enter the bloodstream carried on a binding protein and then are immediately taken up by the liver for hydroxylation, or alternatively by the adipose tissue for storage. The liver hydroxylation of vitamin D yields 25(OH)D, or calcidiol, the major
circulating form of vitamin D in the blood with a half-life of about three weeks; this is the form measured by the commonly ordered “vitamin D test.” (Test results may be broken down by the amount of 25(OH) vitamin D3 versus 25(OH) vitamin D2, but more often only the sum of the two forms is reported.) Circulating 25(OH)D then undergoes a second hydroxylation either in the kidneys or in target tissues to produce the hormonally active form, 1,25(OH)2D, or calcitriol. Circulating 1,25(OH)2D can also be measured, but is most clinically useful in cases of kidney disease, or in diseases that may lead to excessive levels of vitamin D and/or calcium such as sarcoidosis or certain lymphomas.
If serum 25(OH)D comes back below or near the bottom of the laboratory reference range, doctors will typically prescribe vitamin D2 at a dose of 50,000 IU per week for eight weeks. I’ve observed that after this initial treat- ment many patients will continue supplementa- tion with an over-the-counter product containing 400 to 2,000 IU (occasionally as high as 5,000 IU) of vitamin D3 per day, sometimes per the doctor’s advice but more often the patient’s own choosing. There does not always seem to be a clear rationale behind this practice; it may be what the patient finds at the drugstore either in a vitamin D supplement or in a multivitamin, or what the doctor generally recommends for
ARTICLE SUMMARY
• Vitamin D blood testing and oral supplementation have become an almost routine part of conventional medical care.
• Unfortunately, the results of a vitamin D blood test do not always reflect the true picture of an individual's vitamin D status, and whether or not supplementation is warranted and in what amount.
• There is a growing concern that the trend to aim for higher blood levels of vitamin D is not supported by the scientific evidence, and over time may contribute to calcification of the arteries, kidney stones and other health problems.
• Weston A. Price Foundation members will not be surprised by this. Our Foundation has always taught the critical importance of consuming all of the fat-soluble vitamins, as Dr. Price discovered and more recent research has con- firmed.
• Various agency guidelines differ as to the optimum amount of dietary vitamin D. There are a number of limitations to testing, and interpretations of vitamin D levels are presented. Serum levels of 30ng/mL are adequate for preventing bone loss.
• Vitamins A, D and K2work synergistically. Rich dietary sources of all three vitamins can enhance their health benefits while simultaneously eliminating both the need for testing and concern for potential over-supplementation.
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Wise Traditions
SUMMER 2017