Phase angle and cellular health: inflammation and oxidative damage

Phase angle is a composite measure that combines two raw bioelectrical impedance analysis measures: resistance and reactance. Phase angle has been considered an indicator of cellular health, integrity, and hydration. As inflammation and oxidative stress can damage cellular structures, phase angle has potential utility in early detecting inflammatory and oxidative status. Herein, we aimed to critically review the current understanding on the determinants of phase angle and its relationship with markers of inflammation and oxidative stress. We also discussed the potential role of phase angle in detecting chronic inflammation and related adverse outcomes. Several factors have been identified as predictors of phase angle, including age, sex, extracellular to intracellular water ratio, and fat-free mass. In addition to these factors, body mass index (BMI) also seems to influence phase angle. Available data also show that lower phase angle values are correlated (negligible to high correlation coefficients) with higher c-reactive protein, tumour necrosis factor-α, interleukin-6, and interleukin-10 in studies involving the general and aging populations, as well as patients with chronic conditions. Although fewer studies have evaluated the relationship between phase angle and markers of oxidative stress, available data also suggest that phase angle has potential to be used as an indicator (for screening) of oxidative damage. Future studies including diverse populations and bioelectrical impedance devices are required to confirm the validity and accuracy of phase angle as a marker of inflammation and oxidative stress for clinical use.