Vitamin D's importance as a nutrient for the prevention of osteoporosis is well established, especially for the elderly population where a high incidence of vitamin D deficiency is well-documented. However the specific targets of the vitamin in bone have remained largely unknown.
The study, published in the February issue of The Journal of Clinical Investigation (Vol. 116, Issue 2), used mice to show that orally administered vitamin D inhibited the production of a protein called c-Fos.
The c-Fos protein was shown to be a key actor in the development of osteoclasts, multinucleated cells that degrade and reabsorb bone. Vitamin D was then shown to inhibit the c-Fos facilitation of osteoclast formation.
"This finding suggests that the vitamin D receptor inhibits the translation of c-Fos protein, although the underlying molecular mechanism remains elusive," said lead author Hisashi Takasu from the National Centre for Geriatrics and Gerontology, Obu, Japan.
The researchers did not stop at simply identifying the target of vitamin D, but also synthesized vitamin D analogs.
"By screening newly synthesized vitamin D compounds, we identified two analogs, DD280 and DD281, that reduced the level of c-Fos protein more potently than [vitamin D],"said Takasu.
This result prompted the researchers to suggest that the DD281 may warrant a clinical trial.
The research was greeted with great interest by British charity, The National Osteoporosis Society (NOS). Trevor Reid, NOS communications and fundraising manager, told NutraIngredients.com: "This is very interesting research despite being at a very early stage. The NOS is watching with interest the developments in this area and will follow its progress."
"We hope to see further studies and research carried out in human subjects before its potential for use on people with osteoporosis is fully understood," said Reid.
Osteoporosis is estimated to affect about 75 million people in Europe, the USA and Japan. According to the International Osteoporosis Foundation, the total direct cost of osteoporotic fractures is € 31.7 billion in Europe, and $17.5 billion in the US (2002 figure). The total annual cost of osteoporosis in the UK alone is over £1.7 billion (€ 2.5 billion), equivalent to £5 million (€ 7.3 million) each day.
Regular supplementation with vitamin D has been proposed as a simple and inexpensive way of reducing the burden of osteoporosis.
This research follows hot on the heels of other studies about the benefits of vitamin D supplementation, ensuring the vitamin stays in the public spotlight. Recent positive reports linking the vitamin to reduced risks of certain cancers led to a measurable surge in vitamin D sales in the UK, with some retailers reporting 400 per cent increases.