| There is growing support for having a regular | | | | significantly decreased calcium absorption. They |
| vitamin D blood test and maintaining blood levels | | | | updated their guidelines in January, 2008 as |
| at 30 ng/ml or more. The Vitamin D Council | | | | follows: |
| recommends that vitamin D levels of 50-80 ng/ml | | | | - 0-14.9 ng/ml = Severely deficient |
| be maintained year-round, in both children and | | | | - 15.0-31.9 ng/ml = Mildly deficient |
| adults. | | | | - 32.0-100.0 ng/ml = Optimal |
| Vitamin D is an essential element for building | | | | - >100.0 ng/ml = Toxicity possible |
| strong bones and maintaining a strong immune | | | | DR. MICHAEL HOLICK (> 30 ng/ml) |
| system. The symptoms of vitamin D deficiency | | | | Dr. Michael Holick, author of "The UV Advantage" |
| are so subtle that we may not notice that our | | | | recommends that we maintain bloods levels |
| intake is inadequate until our bones are brittle and | | | | above 30 ng/ml. He found that north of the 42 |
| health problems appear. The best way to | | | | latitude (north of Boston) that 1,000 IU of vitamin |
| determine if your vitamin D levels are sufficient is | | | | D a day was unable to raise blood levels above |
| to take the vitamin D blood test 25(OH)D to | | | | 30 ng/ml and he recommended that people take |
| measure 25-hydroxyvitamin D. | | | | 2,000 IU of vitamin D in the winter when the sun |
| There are three things that should be noted about | | | | does not provide enough ultraviolet radiation to |
| this blood test: | | | | support Vitamin D production through the skin. |
| - The 25(OH)D test should not be confused with | | | | Dr. Holick notes that 100% of the vitamin D |
| a test for 1,25-dihydroxyvitamin D. (Levels of | | | | produced from sunlight is bound to the vitamin D |
| 1,25(OH)2D do not typically decrease until vitamin | | | | binding protein while only 60% of the vitamin D |
| D deficiency is severe.) | | | | that is ingested from food or supplements is |
| - Serum concentrations of 25(OH)D are reported | | | | bound to the vitamin D binding protein. Thus, the |
| in both nanograms per milliliter (ng/ml) and | | | | vitamin D that is made in the skin has a longer |
| nanomoles per liter (nmol/l). (1 ng/mL = 2.5 nmol | | | | half-life in the circulation than vitamin D that is |
| l) | | | | ingested. |
| - The test measures the vitamin D circulating in | | | | VITAMIN D COUNCIL (50-80 ng/ml) |
| the blood and not that which is stored in other | | | | The Vitamin D Council recommends that vitamin |
| parts of the body. In 2007, a group of vitamin D | | | | D levels of 50-80 ng/ml be maintained year-round, |
| and nutrition researchers published an editorial | | | | in both children and adults. The Council bases its |
| arguing that we should strive for vitamin D blood | | | | recommendation on research conducted by Bruce |
| test results of 30 ng/mL or more....and that 400 | | | | Hollis which found that the body does not reliably |
| IU/day of vitamin D did little to help us reach this | | | | begin storing vitamin D3 in fat and muscle tissue |
| level. They also stated that approximately 1,700 | | | | until 25(OH)D levels get above 50 ng/ml. The |
| IU of vitamin D are needed daily to raise blood | | | | average person starts to store cholecalciferol at |
| levels from 20 to 32 ng/mL. (Vieth R, | | | | 40 ng/ml but at 50 ng/ml virtually everyone |
| Bischoff-Ferrari H, Boucher BJ, Dawson-Hughes B, | | | | begins to store it for future use. Hollis argues that |
| Garland CF, Heaney RP, et al. The urgent need to | | | | at levels below 50 ng/ml, the body uses up |
| recommend an intake of vitamin D that is | | | | vitamin D as fast as we can make or ingest it. |
| effective. Am J Clin Nutr 2007;85:649-50.) | | | | The Council suggests that 2,000-5,000 IU of |
| The debate over the optimal blood levels is as | | | | vitamin D are needed in the Fall and winter with |
| vigorous as the debate over the vitamin D | | | | the higher level needed in the northern regions |
| dosage required from supplements. As this debate | | | | where the "vitamin D winter" is the longest. |
| is likely to continue for some time, it is useful to | | | | LABORATORY ASSAYS ARE NOW |
| get an overview of all the recommendations...so | | | | STANDARDIZED |
| that we can choose a target for our vitamin D | | | | Until recently, there has been considerable |
| blood test and a vitamin D strategy that will | | | | variability in the assays used by laboratories. This |
| optimize our well-being. | | | | means that compared to the actual concentration |
| MOST EXPERTS RECOMMEND VITAMIN D | | | | of 25(OH)D in a sample of blood serum, a falsely |
| BLOOD LEVELS THAT ARE GREATER THAN 30 | | | | low or falsely high value could be obtained. A |
| ng/ml | | | | standard reference material for 25(OH)D became |
| In 1997, the US Institute of Medicine- Food and | | | | available in July 2009 and will now permit |
| Nutrition Board identified >15 ng/mL (> 37.5 | | | | standardization of values across laboratories. |
| nmol/l) as adequate for bone and overall health in | | | | The U.S. National Health and Nutrition Examination |
| healthy individuals. This is now considered to be | | | | Survey (NHANES III) found that when |
| inadequate by most health care providers. There | | | | researchers gave a vitamin D blood test to over |
| is growing support for levels >30 ng/ml with | | | | 13,000 people in the United States, that 73% had |
| the Vitamin D Council recommending that people | | | | blood levels lower than 30 ng/ml. The Vitamin D |
| try to maintain a 50 ng/ml vitamin D blood level. | | | | Society in Canada reports that 97 percent of |
| This, of course, has implications for how much | | | | Canadians may be vitamin D deficient at some |
| vitamin D we need to get through | | | | point in the year. |
| supplements...especially for people living in northern | | | | Many health experts believe that administering an |
| regions. | | | | annual vitamin D blood test will soon become a |
| Here are some of their arguments and | | | | regular medical practice. But there is no need to |
| recommendations regarding vitamin D blood tests. | | | | wait for these tests to become a common |
| LEGACY HEALTH SYSTEM-PORTLAND OREGON | | | | practice. Patients can work proactively with their |
| (>32 ng/ml) | | | | health care providers to ensure that a 25(OH)D |
| The Legacy Health System (a hospital system | | | | test is not only included in their check-ups...but that |
| based in Portland, Oregon) recently warned that | | | | they have a vitamin D strategy to maintain the |
| 25(OH)D levels less than 32 ng/ml resulted in | | | | optimal blood level of this essential vitamin. |