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年長者每週使用維他命D3可改善維他命D不足 但對神經肌肉功能沒有影響
作者：Laurie Barclay, MD  
出處：WebMD醫學新聞

　　February 18, 2010 — 根據2月3日線上版美國臨床營養期刊(American Journal of Clinical Nutrition)的一篇隨機控制雙盲試驗結果，年長之維他命D不足患者每週使用8400 IU的維他命D3可以增加血清25-hydroxyvitamin D [25(OH)D]濃度。
　　
　　荷蘭阿姆斯特丹Vrije大學醫學中心的Paul Lips等人寫道，年長者經常會發生維他命D不足，而與骨骼和肌肉衰弱以及跌倒有關。我們檢視了每週使用8400 IU的維他命D3對於姿勢穩定度、肌肉強度與安全性的效果。
　　
　　25(OH)D濃度大於等於6 ng/mL而小於等於20 ng/mL的70歲以上者，被隨機分派接受每週8400 IU的維他命D3或安慰劑，研究的主要終點，是使用AccuSwayPLUS平台(麻州Watertown Advanced Medical Technology公司)測量眼睛張開時的正中側面身體搖擺(即測量身體穩定度)。次級終點是此一世代的體能表現量表以及血清25(OH)D濃度，另外，評估安全性與耐受度，使用共變異數模式分析比較治療效果。
　　
　　【隨機研究設計的強度】
　　奧地利維也納醫學大學病理生理學榮譽教授Meinrad Peterlik博士受邀進行獨立評論時向Medscape Nutrition表示，有越來越多研究報告指出，血清25-hydroxyvitamin D[25-(OH)D]濃度低與許多骨骼外疾病和病理狀況有顯著關聯。
　　
　　不過，多數的觀察型研究很少控制可能的干擾因素，而可以提供維他命D狀態不佳和疾病發生率之因果關係的介入型試驗又很少，因此，Lips等人研究的主要強度在於，它是對於一群維他命D供給情況次佳的年長者，以隨機控制多中心試驗評估維他命D3補充品對於定義明確之神經肌肉功能參數、身體搖擺的影響效果。
　　
　　接受安慰劑的病患有112人，不過只有服用8400 IU維他命D3的114人其血清25(OH)D濃度從13.9 ng/mL顯著增加到26.2 ng/mL(P < .001)。16週時的正中側面身體搖擺以及簡短體能表現量表，在治療組之間並無顯著差異。
　　
　　根據開始時搖擺程度分組(≧0.46 vs < 0.46 cm)的事後分析，對於開始時搖擺程度增加的病患，與安慰劑組相比，使用8400 IU的維他命D3治療與顯著降低搖擺有關(P = .047)，但是開始時搖擺程度正常的病患則沒有差異。
　　
　　研究作者寫道，年長、維他命D不足者每週使用8400 IU的維他命D3可增加25(OH)D的濃度，在這類病患中，相較於使用安慰劑者，使用8400 IU的維他命D3治療並不會顯著降低正中側面搖擺，不過，在事後分析中，使用8400 IU的維他命D3治療減少了開始時搖擺程度增加之病患的搖擺情況，每週使用8400 IU維他命D3的耐受良好。
　　
　　維他命D3組的副甲狀腺荷爾蒙值顯著降低，安慰劑組則無，兩組有類似的不良反應事件與發生率，包括高鈣血症、高尿鈣症與肌酸酐值增加。
　　
　　【研究限制】
　　Peterlik博士向Medscape Nutrition表示，雖然結果明確，它們的詮釋因為一些事實而有所阻礙，多數是作者自己的適當表述，不過，他們未能討論整個研究組鈣攝取之適當情況的影響，而這可能對研究結果有所影響。很可能是因為高鈣攝取，而維他命D補充品只有最小的效果，這不令人驚訝，其中一位共同作者最近的一篇研究(Pfeifer等人，Osteoporosis Int. 20:315-322, 2009)顯示，併用維他命D與鈣質補充品對於年長者的肌肉功能參數有正面影響。
　　
　　研究作者所提及的研究限制包括，樣本數少、年長研究對象的健康狀況並不尋常，此外，開始時有正中側面搖擺數據之研究對象的實際人數與沒有跌倒的研究對象人數一致，表示以搖擺測量他們的平衡是適當的，對於這些病患，以治療改善搖擺和體能表現的空間有限。
　　
　　Peterlik博士結論表示，顯然地，身體搖擺情況增加的年長者可以從每天1200 IU的維他命D3併用每天大於1000 mg的鈣而獲得幫助，需要以骨折率作為終點之後續研究，來證明觀察到的身體搖擺減少對於年長者的跌倒和骨質疏鬆骨折發生率有實際影響。
　　
　　Merck藥廠支持本研究，雇用其中5名研究作者，提供研究資金給其他4名研究作者。 Peterlik 博士宣告沒有相關財務關係。
　　
　　Am J Clin Nutr. 線上發表於2010年2月3日。


Weekly Vitamin D3 Improves Vitamin D Insufficiency but Not Neuromuscular Function in Older Adults

By Laurie Barclay, MD
Medscape Medical News

February 18, 2010 — Weekly treatment with 8400 IU of vitamin D3 raises serum 25-hydroxyvitamin D [25(OH)D] concentrations in elderly, vitamin D–insufficient individuals, according to the results of a randomized controlled, double-blind trial reported online February 3 in the American Journal of Clinical Nutrition.

"Vitamin D insufficiency, which is prevalent in older individuals, is associated with bone and muscle weakness and falls," write Paul Lips, from Vrije Universiteit Medisch Centrum, Amsterdam, Netherlands, and colleagues. "We examined the effects of a weekly dose of 8400 IU vitamin D3 on postural stability, muscle strength, and safety."

Participants 70 years or older with 25(OH)D concentrations of 20 ng/mL or less but at least 6 ng/mL were randomly assigned to receive a weekly dose of 8400 IU of vitamin D3 or placebo. The main endpoint of the study was mediolateral body sway with eyes open, measured with use of the AccuSwayPLUS platform (Advanced Medical Technology Inc, Watertown, Massachusetts). The short physical performance battery and serum 25(OH)D concentrations were secondary outcomes. Safety and tolerability were evaluated, and treatments were compared by use of an analysis of covariance model.

Strength of Randomized Study Design

"An increasing number of studies report on significant associations between low serum levels of 25-hydroxyvitamin D (25-(OH)D) and a multitude of extra-skeletal diseases and pathological conditions," Meinrad Peterlik, PhD, MD, professor emeritus of pathophysiology at Medical University Vienna in Vienna, Austria, told Medscape Nutrition when asked for independent comment.

"However, these mostly observational studies are rarely controlled for potential confounders, and interventional trials that would prove a causative relation between a compromised vitamin D status and disease incidence are rare. The main strength of the study by Lips et al. thus lies in the fact that it was designed as a randomized controlled multicenter trial to evaluate the effect of vitamin D3 supplementation on a well defined neuromuscular functional parameter, i.e., body sway, in a group of elderly people with sub-optimal vitamin D supply."

In patients treated with 8400 IU of vitamin D3 (n = 114) but not in patients receiving placebo (n = 112), serum 25(OH)D concentrations increased significantly from 13.9 to 26.2 ng/mL (P < .001). Mediolateral sway and short physical performance battery at 16 weeks were not significantly different between treatment groups.

Treatment with 8400 IU of vitamin D3 was associated with significantly decreased sway vs treatment with placebo (P = .047) in patients with elevated baseline sway but not in patients with normal baseline sway, based on a post hoc analysis of patients subgrouped by baseline sway (? 0.46 vs < 0.46 cm).

"Weekly treatment with 8400 IU vitamin D3 raised 25(OH)D concentrations in elderly, vitamin D–insufficient individuals," the study authors write. "Treatment with 8400 IU vitamin D3 did not reduce mediolateral sway significantly compared with treatment with placebo in this population, although in post hoc analysis, treatment with 8400 IU vitamin D3 reduced sway in the subgroup of patients who had elevated sway at baseline. Weekly treatment with 8400 IU vitamin D3 was well tolerated."

Parathyroid hormone levels decreased significantly in the vitamin D3 group but not in the placebo group. Both groups had similar adverse events and incidences of hypercalcemia, hypercalciuria, and elevated creatinine levels.

Limitations of the Study

"Although the results are straightforward, their interpretation is hampered by a number of facts, most of which are appropriately addressed by the authors themselves," Dr. Peterlik told Medscape Nutrition. "However, they fail to discuss what impact the optimization of calcium intake in the entire study group could have had on the outcome of the study. It could well be that at high calcium intake levels vitamin D supplementation is only minimally effective. This would not be surprising since a recent study by one of the coauthors (Pfeifer et al., Osteoporosis Int. 20:315-322, 2009) shows a positive effect of combined vitamin D and calcium supplementation on parameters of muscle function in elderly people."

Limitations acknowledged by the study authors include small size and unusually healthy condition of the elderly participants. In addition, a substantial number of participants had mediolateral sway values at baseline that were consistent with participants who did not fall, suggesting that their balance as measured by sway was adequate. There may have been little room for improvement of sway and physical performance with treatment in these patients.

"It is clear that elderly individuals with an increased body sway will benefit from a daily dose of 1200 IU vitamin D3 in combination with intake of >?1000?mg calcium per day," Dr. Peterlik concluded. "Additional studies with fracture rates as endpoint are necessary to prove that the observed reduction of body sway actually has a substantial impact on the incidence of falls and osteoporotic fractures in elderly people."

Merck & Co Inc supported this study, employs 5 of the study authors, and provided research grants to 4 other study authors. Dr. Peterlik has disclosed no relevant financial relationships.

Am J Clin Nutr. Published online February 3, 2010.