Interaction Between Vitamin D and Interleukin 6 on Slow Gait Speed: 6-Year Follow-up Data of Older Adults From InCHIANTI

J Gerontol A Biol Sci Med Sci. 2020 May 22;75(6):1161-1166. doi: 10.1093/gerona/glz165.


Background: Whereas the independent effects of biomarkers, including 25-hydroxy vitamin D (25(OH)D), insulin-like growth factor 1, C-reactive protein, and interleukin 6 (IL-6), on gait speed in older adults have been evaluated, their joint effects on gait speed are not well understood.

Methods: Study subjects aged at least 65 at baseline (N = 970) were enrolled in the population-based Invecchiare in Chianti (InCHIANTI) study from 1998 to 2000 and were followed up at 3 and 6 years. All above biomarkers and gait speed data were measured at each of the three time points. Using a generalized estimating equation approach, we determined if slow gait speed (<0.8 m/s) was associated with the biomarkers. Further investigation was conducted for interactions between high IL-6 (≥.87 pg/mL) and other biomarkers focusing on low 25(OH)D (<20 ng/mL).

Results: After controlling for other biomarkers and potential confounders, IL-6 emerged as the only biomarker independently associated with gait speed. The association between high IL-6 and slow gait speed was enhanced by low 25(OH)D, with significant interaction between high IL-6 and low 25(OH)D (p = .038). The odds ratio of slow gait speed for low 25(OH)D and high IL-6 was 1.63 (95% confidence interval [CI]: 1.15, 2.32) compared with the reference groups with both biomarker levels at the other ends.

Conclusion: The association of low vitamin D with slow gait speed statistically interacts with high IL-6. Coexisting vitamin D insufficiency and inflammation may provide a better biomarker for identifying those at risk of developing impairments in gait speed than either factor alone.

Keywords: Gait Speed; IL-6; Interaction; Vitamin D.

Publication types

  • Observational Study
  • Research Support, N.I.H., Intramural

MeSH terms

  • Aged
  • Aged, 80 and over
  • Biomarkers / blood
  • C-Reactive Protein / analysis
  • Female
  • Gait / physiology*
  • Humans
  • Insulin-Like Growth Factor I / analysis
  • Interleukin-6 / blood*
  • Male
  • Prospective Studies
  • Vitamin D / blood*
  • Vitamin D Deficiency / physiopathology
  • Walking Speed / physiology*


  • Biomarkers
  • IGF1 protein, human
  • Interleukin-6
  • Vitamin D
  • Insulin-Like Growth Factor I
  • C-Reactive Protein