Bone breaker. The ruffled surfaces of bone-dissolving osteoclasts (pink) indicate that they are stripping out stressed bone. Credit: Stephen Nesbitt / University College London
Posted on 01/22/2006 8:32:06 PM PST by neverdem
Anyone concerned about their bones is likely to make sure they have plenty of vitamin D, either by getting enough sunshine, eating fish, or taking supplements. Yet scientists know surprisingly little about how the compound works. A new study has finally shed some light on this process, showing how the vitamin takes part in a delicate balancing act between cells that tear down our bones and cells that rebuild them. Vitamin D is a familiar player in bone health. Without sufficient amounts of this hormone, our frames become frail with disorders such as osteoporosis or rickets. But vitamin D has some puzzling effects in the lab. As might be expected, it reduces the number of bone-dissolving cells, or osteoclasts, in mice with a condition resembling osteoporosis. When added to cultured bone marrow, however, vitamin D ramps up the production of these bone destroyers.
So physiologist Kyoji Ikeda and colleagues at the National Center for Geriatrics and Gerontology in Obu, Japan, and Chugai Pharmaceutical Co., in Gotemba, Japan, tried to tease apart the effects. By adding vitamin D to a petri dish full of osteoclast precursors, they discovered that the hormone blocked a signal called RANK ligand that tells these cells to become osteoclasts. That's how vitamin D cuts back on osteoclasts.
Vitamin D performs the opposite trick--boosting osteoclast numbers--via a more circuitous route. When the researchers performed a similar experiment with precursors of bone building cells, the precursors boosted their production of RANK ligand, the group reports in the February Journal of Clinical Investigation. The findings confirm and explain vitamin D's competing effects in the body, say the researchers.
"This [report] actually works out a substantial part of the [vitamin D] mechanism," says endocrinologist T. John Martin of St. Vincent's Institute of Medical Research in Melbourne, Australia. Vitamin D therapy might be particularly useful once the balance has tipped toward bone loss, he says, or if vitamin D analogs can be made to target the precursors of bone-dissolving cells specifically.
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FReepmail me if you want on or off my health and science ping list. My mother fractured her pelvis one week before Christmas. Those who experience the trauma of an osteoporotic hip fracture have a 24% increased risk of dying within one year following the fracture
I'm afraid that as more of all the variants of the human genome are discovered, it's going to become a politically correct mess, just delaying what medical progress and health confering benefits are to be obtained.
No mention of "the hormone."
What hormone?
Vitamin D Is Not A Vitamin But A Steroid Hormone Precursor
(or so I just found by googling)
The average medical school teaches almost nothing about nutrician. Doctors know that their careers may be threatened if they delve into this area.
A hormone is a blood-borne chemical secreted by an endocrine gland and which affects the physiology of organ(s) in other parts of the body.
Biologically-active vitamin D is actually produced via the liver and the kidney. The vitamin D produced by the skin does not have biological activity until it is actrivated by the liver and kidney. So, I wouldn't call it a hormone, but a precursor, in much the same manner that cholesterol is not a hormone but a precursor for steroids made in the ovary, testes, adrenal, etc.
Now I take D every day and my polyps have virtually disappeared.
--Boris
http://search.lef.org/cgi-src-bin/MsmGo.exe?grab_id=0&page_id=2834&query=vitamin%20d&hiword=VITAM%20VITAMER%20VITAMERS%20VITAMI%20VITAMINA%20VITAMINAS%20VITAMINC%20VITAMIND%20VITAMINE%20VITAMINES%20VITAMINIC%20VITAMINK%20VITAMINS%20d%20vitamin%20 "Vitamin D is described a fat-soluble vitamin, but it actually functions as a hormone in the body....."
http://search.lef.org/search/default.aspx?s=1&QUERY=vitamin%20d Bottom of page for beginning of 132 articles on Vit D.
Thanks for the ping. Thanks for the links. Very interesting.
After reading up on Vitamin D a few months ago, I started taking 1000 mg a day from November-April.
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