Phase angle reference values in healthy Chinese adults: A descriptive cross‐sectional study

BACKGROUND: Phase angle serves as a robust indicator of cellular integrity and overall health status. However, reference values for phase angle among healthy Chinese adults remain poorly defined. METHODS: We performed a multicenter descriptive cross-sectional study in healthy Chinese adults from 2021 to 2024. Our primary outcome was phase angle, calculated from the relationship between resistance and reactance measured directly by bioelectrical impedance analysis. Standardized anthropometric and bioelectrical impedance analysis assessments were conducted. We examined associations of phase angle with age, sex, and body mass index using multivariable linear regression and generated sex-, age-, and body mass index-stratified percentiles. RESULTS: We analyzed 40,074 healthy adults (46.9% men; mean ± SD age 42.8 ± 12.9 years; mean ± SD body mass index 24.2 ± 3.5 kg/m²) who attended routine health examinations at three hospitals in Northern, Eastern, and Southwestern China. The mean ± SD phase angle was 5.52 ± 0.79°, with significantly higher values in men compared with women (5.95° vs 5.14°, P < 0.001). Phase angle positively correlated with body mass index (r = 0.35) and negatively with age (r = -0.20) (both P < 0.001). Peak phase angle values were observed in individuals aged 30-39 years and declined thereafter. Device type showed no significant effect on phase angle measurements. CONCLUSION: We established the first large-scale, sex-, age-, and bioelectrical impedance analysis-specific phase angle reference ranges for healthy Chinese adults. These normative values provide an essential foundation for clinical application of phase angle in health assessment, early disease screening, and individualized nutrition and medical interventions.