ビタミンDとサルコペニア進行の関連論文

今日は、ビタミンDとサルコペニア進行の関連を見た論文を紹介します。

David Scott, Leigh Blizzard, James Fell, Changhai Ding, Tania Winzenberg and Graeme Jones: A prospective study of the associations between 25-hydroxyvitamin D, sarcopenia progression and physical activity in older adults. Clinical Endocrinology (2010) 73, 581–587

ビタミンDとサルコペニアの関連を見た論文はいくつもありますが、この論文の特徴はビタミンDがサルコペニア進行の独立因子であることを初めて検証した前向きコホート研究ということです。

ビタミンDが低い方は正常の方と比較して、平均2.6年のフォローアップ期間後に、四肢の筋肉量、下肢筋力、下肢の筋肉の質（下肢筋力÷下肢筋肉量）、身体活動量（歩数）が有意に低くなりました。これは日照時間と身体脂肪量で調整した後の結果です。

ビタミンDが正常より低い場合には骨粗鬆症だけでなくサルコペニアが進行しやすい可能性がありますので、ビタミンDをサプリメントで補給する適応はあると思います。正常範囲内にあればもちろん補給する必要はありません。ただ、保険診療では血中ビタミンDを測定できないことが問題です。

Abstract
Objective  Low 25-hydroxyvitamin D (25OHD) levels may be associated with both sarcopenia (the age-related decline in muscle mass and function) and low physical activity (PA). Our objective was to describe prospective associations between 25OHD, muscle parameters, and PA in community-dwelling older adults. Design  Prospective, population-based study with a mean follow-up of 2·6 ± 0·4 years. Patients  Six hundred and eighty-six community-dwelling older adults (49% women; mean ± SD 62 ± 7 years old). Measurements  Appendicular lean mass percentage (%ALM) and body fat assessed by Dual-energy X-ray Absorptiometry, leg strength by dynamometer, leg muscle quality (LMQ), PA assessed by pedometer, self-reported sun exposure by questionnaire, and serum 25OHD measured by radioimmunoassay. Results  Participants with 25OHD ≤50 nm had lower mean %ALM, leg strength, LMQ and PA (all P < 0·05). As a continuous function, baseline 25OHD was a positive independent predictor of change in leg strength (β = 5·74 kg, 95% CI 0·65, 10·82) and LMQ (β = 0·49 kg/kg, 95% CI 0·17, 0·82). Also, change in 25OHD was positively predicted by baseline %ALM (β = 2·03 pm/p.a., 95% CI 0·44, 3·62) leg strength (β = 0·30 pm/p.a., 95% CI 0·06, 0·53), LMQ (β = 4·48 pm/p.a., 95% CI 0·36, 8·61) and PA (β = 2·63 pm/p.a., 95% CI 0·35, 4·92) after adjustment for sun exposure and body fat. Conclusions  25OHD may be important for the maintenance of muscle function, and higher skeletal muscle mass and function as well as general PA levels may also be beneficial for 25OHD status, in community-dwelling older adults.