維生素D與老年人的神經肌肉功能有關


  Sept. 28, 2005 (那什維爾) - 根據荷蘭的研究者在美國骨骼與礦物質研究學會(ASBMR) 第27屆年會表示,身體血清中的維生素D減少會使得老年人更容易發生跌倒。
  
  荷蘭阿姆斯特丹Vu大學醫學中心的博士班研究生Ilse Wicherts表示,維生素D過低會導致較差的身體機能;這項研究顯示,神經肌肉功能較低的患者,其維生素的濃度明顯低於正常值。
  
  ASMBR年輕研究員獎得獎人Wicherts補充指出,這些老年人本就比較脆弱,行動不便致使他們成為跌倒及骨折的高危險群。
  
  在Wicherts的研究中,試驗者為1238位平均年齡為75歲的女性和男性,血清維生素的濃度偏低,神經肌肉功能也較低;本研究在阿姆斯特丹縱向老化研究計畫中(LASA)進行。
  
  通常會用來評量神經肌肉功能的方式,含五個chair stands來測量肌肉的力量,行走測試來測量平衡,前後直排站立來測試協調;另外,測試者必須單腳站立,另一隻腳要往後方伸直來測量行動力;每一項功能測試皆以秒評分,而且用分數來分類,根據四分法從1到4作分類;肌肉力量和平衡的總功能分數範圍是0到12;研究者會因年紀、性別和身體能量指數不同而使用多程變化回歸分析作調整。
  
  11%的試驗者之血清維生素D少於25nmol/L,37%介於25和50 nmol/L,33%介於50和75 nmol/L,17%高於75nmol/L。
  
  隨著血清的維生素D的增加,chair stands、行走測試和前後直排站立所測出的分數都顯示出明顯的改進。
  
  試驗者的維生素D在25nmol/L時,功能指數為4.9,在25和50 nmol/L時則為6.82,50和75 nmol/L時為8.10,試驗者維生素D在75 nmol/L或更高時,指數為8.72 。
  
  Wicherts表示,血清增加25(OH)D時,功能分數的改變有明顯的增加,所以它是呈現一個線性級數。
  
  Wicherts指出,當研究者調整過年齡、性別、身體質量指數、吸菸、飲酒等因素後,血清的維生素D在高於50 nmol/L時其功能的指數有明顯增加;相較於維生素D高於75 nmol/L及如果低於25 nmol/L時,功能指數會降低18%,相較於25及50 nmol/L之間者,則會降低5%。
  
  Wiecherts向Medscape表示,血清維生素D低落時,體能狀況會降低,而且會隨濃度之降低而更形嚴重。
  
  ASBMR的總裁當選人Elizabeth Shane醫師向Medscape表示,這是一個非常重要的研究,因為維生素D不只對骨質的健康很重要,對神經肌肉的穩定性也很重要;骨折不僅是骨質的問題,也是導致跌倒的主要因素。
  
  Shane醫師表示,對老年人而言,骨折的傾向會因為兩個交叉因素而增加;適度的維生素D可以改善肌肉強度,防止老年人的跌倒狀況。

Vitamin D Linked With Neuromus

By Linda Little
Medscape Medical News

Sept. 28, 2005 (Nashville) — Low serum levels of vitamin D in the body may make elderly persons more susceptible to falls, Netherlands researchers reported here at the American Society of Mineral and Bone Research (ASBMR) 27th annual meeting.

"Low levels of vitamin D were associated with low physical performance," said Ilse Wicherts, a doctorate student at Vu University Medical Center in Amsterdam, the Netherlands. "This study shows that neuromuscular performance in those with lower levels of vitamin D was significantly lower than those with adequate levels.

"These individuals already are fragile," added Ms. Wicherts, the winner of an ASMBR Young Investigator Award. "The lack of mobility places them at high risk of falls and fractures."

In the study 1,238 men and women (mean age, 75 years) by Ms. Wicherts and colleagues, a low serum level of vitamin D was associated with lower neuromuscular performance. The study was undertaken within the framework of the Longitudinal Aging Study Amsterdam (LASA).

Neuromuscular performance was measured by five chair stands for muscle strength, a walking test for balance, and tandem stand testing coordination and mobility where participants must stand with one foot in front of the other. Each performance test was scored in seconds and was classified with scores from 1 to 4 according to quartiles of distribution. The total performance score for muscle strength and balance ranged from 0 to 12. The researchers used a multivariate regression analysis adjusted for age, sex, and body mass index.

Eleven percent of the participants had serum vitamin D levels less than 25 nmol/L, 37% had levels between 25 and 50 nmol/L, 33% had levels between 50 and 75 nmol/L, and 17% had levels of 75 nmol/L or above.

Scores for chair stands, the walking test, and tandem stand each showed significant improvement with increased serum levels of vitamin D.

Participants with vitamin D at 25 nmol/L had a performance score of 4.9 while those with vitamin D levels between 25 and 50 nmol/L had scores of 6.82 and those with levels between 50 and 75 nmol/L had scores of 8.10. Participants with vitamin D levels of 75 nmol/L or higher had performance scores of 8.72.

"There was a linear progression," Ms. Wicherts said. "The change in performance scores with increasing serum 25(OH)D was significant for all steps."

When researchers adjusted for age, sex, body mass index, smoking, and alcohol consumption, the performance score increased significantly with serum vitamin D levels up to 50 nmol/L. Performance was reduced 18% if the vitamin D levels were lower than 25 nmol/L compared with participants with levels of 75 nmol/L or higher and 5% if vitamin D levels were between 25 and 50 nmol/L after adjusting for other risk factors, Ms. Wicherts said.

"Persons with low serum vitamin D levels had a higher risk for low physical performance," Ms. Wiecherts told Medscape. "The strongest effects were found in persons with a major deficiency."

"This is a very important study because it suggests that vitamin D is not only important for bone health, but is important in neuromuscular stability," said Elizabeth Shane, MD, president-elect of ASBMR. "Bone fracture is due to not only bone issues, but issues contributing to falls.

"There is a two-pronged effect here that can increase the propensity for fractures in the elderly," Dr. Shane said. "Adequate Vitamin D can aid in improving muscle strength and preventing falls in this older age group."

ASBMR 27th Annual Meeting: Abstract 1134. Presented September 26, 2005.

Reviewed by Gary D. Vogin, MD

    
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