Vitamin D Deficiency Speeds Up Aging Of Bones

Editor's Choice Academic Journal Main Category: Bones / Orthopedics Also Included In: Nutrition / Diet; Seniors / Aging; Endocrinology Article Date: 15 Jul 2013 - 0:00 PDT

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The bones of people with vitamin D deficiency tend to age faster compared to those with healthy levels of "the sunshine vitamin", American and German scientists found. The researchers also showed that low levels of vitamin D undermine bone quality.

The study has been published in the journal Science Translational Medicine, and is titled "Vitamin D Deficiency Induces Early Signs of Aging in Human Bone, Increasing the Risk of Fracture."

Leader of the US team, Robert Ritchie, who works at Berkeley Lab's Materials Sciences Division and the University of California Berkeley's Materials Science and Engineering Department, said

"The assumption has been that the main problem with vitamin D deficiency is reduced mineralization for the creation of new bone mass, but we've shown that low levels of vitamin D also induces premature aging of existing bone."

Leader of the German team, Björn Busse, of the Department of Osteology and Biomechanics at the University Medical Center in Hamburg, said "Unraveling the complexity of human bone structure may provide some insight into more effective ways to prevent or treat fractures in patients with vitamin D deficiency."

Vitamin D plays a major role in the absorption of calcium. Human skin manufactures vitamin D when it is exposed to sunlight, that is why it is known as "the sunshine vitamin".

Vitamin D deficiency, rickets, osteomalacia and osteoporosis

If vitamin D levels drop too much, the human body replenishes calcium blood levels by removing some from bone. This undermines the mineralization process required for the formation of new bone. Children who are deficient in vitamin D are much more likely to develop rickets.

Adults with vitamin D deficiency are more likely to develop osteomalacia, the adult version of rickets. Osteomalacia refers to the softening of bones, which are much more likely to bow and fracture. Osteomalacia is different from osteoporosis. Osteomalacia is a defect in the bone-building process, while osteoporosis refers to the weakening of already-constructed bone. The main symptoms of osteomalacia are bone pain and muscle weakness.

Treatment for osteomalacia includes calcium and vitamin D supplements. However, in the best of cases only modest improvements in bone mineral density are achieved. This suggests there are other factors that reduce fracture risk.

Ritchie said "We hypothesized that restoring the normal level of vitamin D not only corrects the imbalance of mineralized and non-mineralized bone quantities, but also initiates simultaneous multiscale alterations in bone structure that affects both the intrinsic and extrinsic fracture mechanisms."

The researchers tested this hypothesis by gathering samples of liliac crest bone cores from 30 volunteers, half of them were vitamin-D deficient and had early signs and symptoms of osteomalacia.

The authors defined normal vitamin D levels as having a serum concentration of at least 20 micrograms per liter. The mean serum concentration in the vitamin D deficient group was 10 micrograms per liter.

The scientists analyzed the bone samples using FTIR (Fourier Transform Infrared) spectroscopy and X-ray computed microtomography.

Ritchie said "We were interested in spatially resolved data that would help us to follow the formation of cracks under mechanical loading. The ALS beamlines enabled us to measure the structure/composition and mechanical properties of the bone samples at different size-scales, ranging from nanometers to micrometers. We measured the resistance to crack growth and by following crack growth in real-time were able to observe how cracks and structure interact. This enabled us to relate mechanical properties to specific structural changes."

The team found that the participants who were vitamin-D deficient:

Had less overall mineralization due to a decline of mineralized bone Under the new non-mineralized surfaces, the bone displayed the structural characteristics of more brittle and older bone. It was more heavily mineralized underneath.

Busse said:

"These islands of mineralized bone were surrounded by a collagenous boundary that prevented them from being properly remodeled. Cut off from a supply of osteoclasts, the cells that normally remodel the bone, these isolated sections of mineralized bone begin to age, even as overall bone mineralization decreases from a lack of calcium."

Ritchie said " In situ fracture mechanics measurements and CT-scanning of the crack path indicated that vitamin D deficiency increases both the initiation and propagation of cracks by 22- to 31-percent."

The authors say that at risk patients should have their vitamin D levels monitored and maintained at healthy levels in order to protect the structural integrity of bones and "avoid mineralization defects and aging issues that can lead to a risk of fractures."

The U.S. Preventive Services Task Force announced earlier this year in Annals of Internal Medicine that vitamin D and calcium supplements do not prevent fractures.

Many vitamin D supplements less potent than manufacturers claim - a study conducted by a team at Kaiser Permanente and published in JAMA Internal Medicine (February 2013 issue) discovered that over-the-counter vitamin D supplements can have between 9% and 146% of what their labels claim.

Lead author, Erin S. LeBlanc, MD, MPH, said "We were surprised by the variation in potency among these vitamin D pills. The biggest worry is for someone who has low levels of vitamin D in their blood. If they are consistently taking a supplement with little vitamin D in it, they could face health risks."

Vitamin D deficiency a growing problem in the USA and UK

UK doctors report seeing a growing number of patients with serious vitamin D deficiencies - Dr Benjamin Jacobs of the Royal National Orthopaedic Hospital (RNOH) in Middlesex, England, said in an interview with the BBC "research indicates that in many parts of the country the majority of children have a low level of vitamin D".

Vitamin D deficiency common in all age groups in the USA - the Endocrine Society published their Clinical Practice Guidelines on vitamin D in the Journal of Clinical Endocrinology & Metabolism (July, 2011 issue). The authors explained that vitamin D deficiency is not only a problem in the USA, but throughout the whole world.

Michael F. Holick, PhD, MD, of the Boston University School of Medicine and chair of the task force that authored the clinical guidelines, said "Vitamin D deficiency is very common in all age groups and it is important that physicians and health care providers have the best evidence-based recommendations for evaluating, treating and preventing vitamin D deficiency in patients at highest risk. The Society's new Clinical Practice Guideline was developed by experts in the field who carefully reviewed the current literature and features the latest and most comprehensive recommendations available on the prevention and treatment of vitamin D deficiency."

Written by Christian Nordqvist Copyright: Medical News TodayNot to be reproduced without permission of Medical News Today

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"Vitamin D Deficiency Induces Early Signs of Aging in Human Bone, Increasing the Risk of Fracture" Björn Busse, Robert O. Ritchie et alSci Transl Med 10 July 2013 5:193ra88. [DOI:10.1126/scitranslmed.3006286]

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Title : Vitamin D Deficiency Speeds Up Aging Of Bones
Published on : Monday, July 15, 2013
Category : Vitamin D
Post URL : http://internal-med.blogspot.com/2013/07/vitamin-d-deficiency-speeds-up-aging-of.html