Serum 25-hydroxyvitamin D, plasma klotho, and lower-extremity physical performance among older adults: Findings from the InCHIANTI Study

Authors

• M Shardell
• RD Semba
• RR Kalyani
• GE Hicks
• S Bandinelli
• L Ferrucci

Abstract

Background: The hormone klotho is encoded by aging-suppressor gene klotho and has multiple roles, including regulating mineral (calcium and phosphate) homeostasis. Vitamin D also regulates mineral homeostasis and upregulates klotho expression. Klotho positively relates to longevity, upper-extremity strength, and less disability in older adults; however, it is unknown whether circulating klotho relates to lower-extremity physical performance or whether the relation of vitamin D with physical performance is mediated by klotho. Methods: Klotho and 25-hydroxyvitamin D [25(OH)D] were measured in 860 participants aged ≥ 55 years in InCHIANTI, a prospective cohort study comprising Italian adults. Lower-extremity physical performance was measured using the Short Physical Performance Battery (SPPB), a summary score of balance, chair stand ability, and walking speed. Weighted estimating equations related plasma klotho and serum 25(OH)D concentrations measured at one visit to SPPB measured longitudinally at multiple visits. Results: Each additional natural log of klotho (pg/mL) was associated with 0.47 higher average SPPB scores (95% confidence interval [CI] 0.08 to 0.86, p-value=0.02) after adjustment for covariates, including 25(OH)D. Each natural log of 25(OH)D (ng/mL) was associated with 0.61 higher average SPPB scores (95% CI 0.35 to 0.88, p-value

Scientific Focus Area: Epidemiology

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