内蔵肥満、サルコペニア、ビタミンD欠乏の関連

内蔵肥満、サルコペニア、ビタミンD欠乏の関連を調査した韓国の横断研究を紹介します。

Seo JA, Cho H, Eun CR, Yoo HJ, Kim SG, Choi KM, Baik SH, Choi DS, Park MH, Han C, Kim NH. Association Between Visceral Obesity and Sarcopenia and Vitamin D Deficiency in Older Koreans: The Ansan Geriatric Study. J Am Geriatr Soc. 2012 Feb 8. doi: 10.1111/j.1532-5415.2012.03887.x. [Epub ahead of print]

484人の65歳以上の韓国の高齢者が対象です。内蔵肥満はCTでの内臓脂肪面積が100cm2以上、サルコペニアはDEXAで骨格筋指数（四肢骨格筋量÷身長÷身長）が若年の1標準偏差以下で診断しています。

結果ですが、ビタミンD血中濃度は、収縮期血圧、内臓脂肪面積、体脂肪率と負の関連を認めました。一方、四肢骨格筋量と正の関連を認めました。多変量解析では男性のみ、内臓脂肪面積、四肢骨格筋量ともビタミンD血中濃度と独立して関連していました。

結論として内臓脂肪が多く骨格筋量が少ない場合に、ビタミンD血中濃度の低値を韓国男性で認めました。ちなみにビタミンDの中央値は男性で15.9ng/ml、女性で11.8ng/mlで、ビタミンD欠乏の定義を20ng/ml未満とすると、男性の69%、女性の86.9%が該当しました。

サルコペニアとビタミンD欠乏の関連はいくつも指摘されていますが、内臓脂肪とビタミンDの関連はあまり知りませんでした。先日、ビタミンDとカルシウムを強化したオレンジジュースを毎日飲むことで内臓脂肪が減少するという報告がありましたが、本当かな…とまだ疑わしく思っています。

Abstract
OBJECTIVES: To investigate whether vitamin D levels are independently associated with visceral obesity, sarcopenia, or sarcopenic obesity.
DESIGN: Cross-sectional.
SETTING: Population-based sample of elderly adults living in Ansan, Korea.
PARTICIPANTS: Two hundred sixteen men and 268 women aged 65 and older.
MEASUREMENTS: Serum 25-hydroxyvitamin D (25(OH)D) levels, visceral fat area (VFA) according to abdominal computed tomography scanning, and body composition (body fat percentage, appendicular skeletal muscle mass (ASM)) using dual-energy X-ray absorptiometry. Visceral obesity was defined as VFA of 100 cm(2) or greater and sarcopenia as ASM/height(2) more than 1 standard deviation (SD) below the sex-specific mean of a young reference group.
RESULTS: The adjusted 25(OH)D level for men was negatively associated with systolic blood pressure, VFA, and body fat percentage but positively associated with ASM. In women, waist circumference, triglyceride levels, and VFA were negatively correlated with 25(OH)D levels. In the joint regression model, VFA and ASM were independently associated with 25(OH)D levels (β = -0.078, P = .01 and β = 0.087, P = .02, respectively) per 1SD difference in VFA and ASM in men but not women. When participants were categorized according to four visceral obesity and sarcopenia categories, adjusted mean 25(OH)D level was lower in men with visceral obesity than in men without but was not affected by the presence or absence of sarcopenia.
CONCLUSION: Greater visceral fat and lower muscle mass were associated with lower 25(OH)D levels in elderly Korean men, suggesting that screening for vitamin D deficiency may be appropriate in older Koreans with visceral obesity or sarcopenia. Sarcopenic obesity as defined according to prespecified criteria did not have an additive association with 25(OH)D levels.