Table 1.

Summary of the main results of the relationship between phase angle, inflammatory and oxidative stress markers

Authors/ year Country	Population	Study design	Device type, model (manufacturer, country)	BIA protocol	Marker	PhA / R / Xc	Association coefficient	p-value	Main conclusion	Adjustments
Inflammation
Johansen et al., 2003 [74] US	- N = 54 (18 ♀) - Patients undergoing HD treatment - Age: 51.5 ± 17 y	Longitudinal	SF-BIA, model NR (RJL Systems®, USA)	NR	IL 1-β	5.3 ± 1.5° / NR / NR	NR	0.004	Negative association with IL1-β	Age, sex, race, diabetes status, and dialysis vintage
Demirci et al., 2010 [75] Turkey	- N = 95 (53 ♀) - Patients undergoing PD treatment - Age: 50 ± 13 y - BMI: 26.0 ± 3.9 kg/m2 - Diabetes: 10.5%	Case-control	MF-BIA, QuadScan 4000 (Bodystat®, Isle of Man)	- Empty peritoneal cavity - ≥ 15 min in supine position prior to test.	CRP, albumin	Men: 5.8 ± 1.4° / NR / NR; women: 5.7 ± 1.0° / NR / NR	CRP: r = − 0.330 Albumin: r = 0.440	All p < 0.01	Negative association with CRP and positive association with albumin	NR
Stobäus., 2012 [39] Germany	- N = 777 (410 ♀) - Hospitalized patients - Age: 53.6 ± 16.7 - OW/OB: 37.8% - Malnutrition by SGA: 54.8% - Malignant tumours: 34%	Cross-sectional	MF-BIA, Nutrigard M (Data Input®, Germany)	- As described in Kyle et al. [97]	CRP	4.91 ± 1.17° / NR / NR	Unadjusted analysis: R = − 0.248 Adjusted analysis: β = −0.003	All p < 0.0001	Negative association with CRP	Regression analysis was adjusted for age, sex, BMI, nutritional status, disease, and inflammation
Beberashvili et al., 2014 [76] Israel	- N = 91 (34 ♀) - Patients undergoing HD treatment (all clinically stable) - Age: 64.0 ± 11.5 y	Cohort study	MF-BIA, Nutrigard M (Data Input®, Germany)	- As described in Kyle et al. [97]	IL-6	4.7 ± 1.3° / NR / NR	Correlations between changes in IL-6 and changes in PhA: r = − 0.32	0.005	PhA changes over time were associated with lower IL-6 levels	Partial correlation adjusted for age, sex, diabetes, dialysis vintage, and cardiovascular disease history
Beberashvili et al., 2014 [79] Israel	- N = 250 (82 ♀) - Patients undergoing HD treatment - Age: 68.7 ± 13.6 y	Cohort study (baseline assessment)	MF-BIA, Nutrigard M (Data Input®, Germany)	- As described in Kyle et al. [97]	Albumin, IL-6, MIS	4.7 ± 1.3° / NR / NR	NR	All p < 0.001	Patients in the lowest PhA tertile (≤ 4.0°) had the highest IL-6 concentrations and MIS values but the lowest albumin concentrations	NR
Tsigos et al., 2015 [80] Italy	- Outpatients (routine check-up) - Group A: N = 10,416 (1,606 ♀); (−)OW/OB/MUS; Age: 35.7 ± 11.0; BMI: 24.3 ± 2.5 kg/m2 - Group B: N = 58,710 (53,129 ♀); (−)OW/OB (+)MUS; Age: 41.2 ± 12.5; BMI: 23.3 ± 2.6 kg/m2 - Group C: N = 30,445 (15,312 ♀); (+)OW/OB (−)MUS; Age: 43.1 ± 12.7; BMI: 31.6 ± 5.0 kg/m2	Case-control	MF-BIA, BIA-ACC® (Biotekna srl., Italy)	- Supine position - Standard placement of electrodes	CRP	Group A: 4.89 ± 1.82° / NR / NR, group B: 3.26 ± 1.38° / NR / NR, group C: 3.69 ± 1.51° / NR / NR	R2 = 0.759 (negative slope)	NR	Negatively correlation with CRP	NR
Barrea el al., 2016 [81] Italy	- N = 180 (52 ♀) - Patients with psoriasis - Age: median (range), 50 (21 − 65) y - BMI: 30.2 ± 6.1 kg/m2 - OW/OB: 77.8% - Diabetes: 22.8%	Case-control	SF-BIA, BIA 101 (Akern Bioresearch, Italy)	- Supine position - Limbs slightly apart the body - Fasting and not exercising for 6 h prior test - No alcohol intake for 24 h prior test - Without shoes and socks - Contact areas scrubbed with alcohol	CRP	5.2 ± 1.0° 504.5 ± 85.8 Ω / 45.4 ± 9.2 Ω	r = − 0.283	< 0.001	Negatively correlation with CRP	BMI
Sarmento-Dias et al., 2017 [77] Portugal	- Patients undergoing PD treatment - Cross-sectional: N = 61 (27 ♀); age = 48 ± 13 y; residual renal function: 95% - Longitudinal: N = 33 (15 ♀); age: 47.8 ± 12 y	Cross-sectional; longitudinal analysis of a subgroup of patients	MF-BIA, InBody S10 (Biospace, Korea)	NR	CRP, albumin	NR for cross-sectional analysis Longitudinal: PhA at baseline: 5.6 ± 1.4° PhA at follow-up: 6.0 ± 1.1°	Cross-sectional: CRP: β = −0.419 Albumin: β = 0.302 Longitudinal: CRP: r = − 0.426 (correlation between % change of both variables)	Cross-sectional: CRP: p = 0.003 Albumin: p = 0.047 Longitudinal: CRP: p = 0.021	Cross-sectional: Negative association with CRP and positive with albumin Longitudinal: PhA change negatively associated with changes in CRP levels	Cross-sectional: Multivariable analysis including age, ultrafiltration volume, serum urea, residual renal function, fat-free mass, Charlson comorbidity index Longitudinal: NR
Moreto et al., 2017 [86] Brazil	- N = 417 (341 ♀) - General population - Age: 53.9 ± 9.4 y - OW/OB: 72% - Metabolic syndrome: 52%	Cross-sectional	SF-BIA, Biodynamics 450, (Biodynamics® Corp., USA)	- No vigorous exercises for 24 h prior test - No alcohol/ caffeinated drinks for 72 h prior test - Emptied bladder - Not during menstruation (women)	CRP	NR / NR / NR	OR = 1.62 for CRP ≥ 3.0 mg/L	< 0.05	Higher CRP increased the odds of low PhA	Age, sex, BMI, and muscle mass index
Tomeleri et al., 2018 [84] Brazil	- N = 46 ♀ - Older women - Age, Int: 71.0 ± 5.4 y; Ctr: 68.8 ± 4.6 y - BMI, Int: 26.8 ± 4.3 kg/m2; Ctr: 26.9 ± 4.1 kg/m2	RCT	MF-BIA, Hydra ECF/ICF 4200 (Xitron Technologies, USA)	- Supine position for 5 min prior test - Euhydration by post-voiding first-morning body weights and urine color	IL-10, TNF-α and CRP	Int: 5.4 ± 0.6° / 560.3 ± 56.1 Ω/ 53.3 ± 7.9 Ω; Ctr: 5.6 ± 0.5° / 579.8 ± 71.5 Ω / 57.0 ± 9.8 Ω	Unadjusted analysis: TNF-α (r = − 0.71); IL-10 (r = 0.46); CRP (r = − 0.65) (correlation between % change of both variables)	< 0.01	Negative association with TNF-α and CRP, and positive association with IL-10	NR
Tomeleri et al., 2018 [83] Brazil	- N = 155 ♀ - Older women - Age: 67.7 ± 5.7 y - BMI: 27.0 ± 4.4 kg/m2 - 75% of women had up to two diseases	Cross-sectional	MF-BIA, Hydra ECF/ICF 4200 (Xitron Technologies, USA)	- Supine position - Voided bladder 30 min prior test - Fasting for 4 h prior test - No strenuous exercise for 24 h - No alcohol/ caffeinated drinks for 48 h prior test - Euhydration confirmed by post-voiding first-morning body weights and urine color - Metals removed - Exam table isolated from electrical conductors - BIA calibrated	IL-6, TNF-α and CRP	5.7 ± 0.6° / NR / NR	Unadjusted analysis: TNF-α (r = −0.63); IL-6 (r = − 0.55); CRP (r = − 0.33) Adjusted analysis: TNF-α (β = −0.84); IL-6 (β = −0.97); CRP (β = −0.58)	< 0.05	Negative association with TNF-α, CRP and IL-6	Age, trunk fat mas, appendicular lean soft tissue, and comorbidities
Wang et al., 2019 [78] China	- N = 144 (50 ♀) - Patients with CKD - Age, median (IQR): 53 (38 − 63) y - BMI, median (IQR): 24.8 (22.6 − 27.4) kg/m2 - CVD: 22.2% - Diabetes: 33.3% - Hypertension: 75.7%	Cross-sectional	BIS-BIA, BCM (Fresenius Medical Care, Germany)	- Electrodes attached to hand and foot (nondominant side) - Supine position for ≥ 5 min prior test	MIS	5.38 ± 1.25° / NR / NR	Unadjusted analysis: r = − 0.475 Adjusted analysis: β = −0.842	< 0.005	Negative association with MIS. Association remained significant in multivariable analysis.	Age, sex, diabetes, handgrip strength, BMI, eGFR, overhydration, albumin, IL 6
Barrea et al., 2020 [82] Italy	- N = 15 (9 ♀) - Adult patients with Prader–Willi Syndrome - Age: 28.0 ± 6.8 y - BMI: 43.8 ± 10.7 kg/m2	Cross-sectional	SF-BIA, BIA 101 (Akern Bioresearch, Italy)	- As described in Kyle et al. [97]	CRP	4.5 ± 0.8° / 445.6 ± 63.7 Ω / 35.1 ± 9.4 Ω	r = − 0.69	0.01	Negative association with CRP	Sex, BMI, and waist circumference
Barrea et al., 2021 [87] Italy	- N = 1855 (1175 ♀) - General population - Age, ♂: 34.8 ± 11.3 y; ♀: 34.4 ± 11.2 y - BMI, ♂: 33.8 ± 8.1; ♀: 35.6 ± 8.6 - OW/OB: 84.9%	Cross-sectional	SF-BIA, BIA 101 (Akern Bioresearch, Italy)	- As described in Kyle et al. [97]	CRP	♂: 6.1 ± 0.8° / 471.5 ± 90.2 Ω / 49.9 ± 10.3 Ω; ♀: 5.6 ± 0.7° / 481.2 ± 85.7 Ω / 46.5 ± 9.4 Ω	Unadjusted analysis: r = − 0.55 Adjusted analysis: β = −0.35	< 0.0001	Negative association with CRP	Age, sex, physical activity, BMI, waist circumference, and PREDIMED score
Cornejo-Pareja et al., 2021 [54] Spain	- N = 127 (52 ♀) - Patients with COVID-19 - Age, median (IQR): 69 (59 − 80) y - BMI, median (IQR): 28.2 (25.7 − 31.8) kg/m2 - OW/OB: 60.6% - Diabetes: 29.1% - Dyslipidemia: 40.9% - Hypertension: 59.1% - CVD: 20.5% - Lung disease: 16.5% - Chronic renal failure: 14.2% - ICU admission: 18.1%	Cohort study	SF-BIA, BIA 101 Whole Body BIVA (Akern Bioresearch, Italy)	- Standard protocol - Daily check for accuracy of BIA device	CRP, Albumin	Median (IQR): 4.4 (3.2 − 5.4)° / R/height: 302.5 (272.2 − 366.3) Ω / Xc/height: 24.7 (16.3 − 31.1) Ω	NR	< 0.001	Patients in the lowest standardized PhA quartile had increased inflammation (high CRP, low albumin)	NR
Moya-Amaya et al., 2021 [88] Spain	- N = 18 (0 ♀) - Professional soccer players	Clinical trial	MF-BIA, MC-780 MA (Tanita Corp., Japan)	- Fasting for 8 h - Morning of the competitive match and 36 h after the match - No moderate/ intense exercise 24 h prior test - Voided bladder - Metals removed	CRP	7.69 ± 0.38° / NR / NR	r = 0.554	0.017	Positive association with CRP	NR
Barrea et al., 2022 [85] Italy	- N = 260 ♀ - Women with OW/OB - Age: 37.6 ± 14.1 y - BMI: 35.7 ± 5.4 kg/m2 - OW/OB: 100%	Pilot clinical study	SF-BIA, BIA 101 (Akern Bioresearch, Italy)	- As described in Kyle et al. [97]	CRP	At baseline: 5.5 ± 0.8° / 478.0 ± 73.1 Ω / 46.3 ± 9.4 Ω	Correlation between changes in PhA and changes in CRP: r = − 0.16	0.024	Negative association with CRP	Age, physical activity, BMI and waist circumference
Oxidative stress
Zouridakis et al., 2016 [89] Greece	- N = 30 (14 ♀) - Patients with CKD - Age: 64 ± 14 y	Case-control	SF-BIA, BIA 101 using the Bodygram software (Akern Bioresearch, Italy)	NR	TAC	At baseline: 5.9 ± 0.9° / 500.5 ± 102.9 Ω / 50.8 ± 9.9 Ω	r = 0.606	< 0.001	Positive correlation with TAC	NR
Tomeleri et al., 2018 [84] Brazil	- N = 46 ♀ - Older women - Age: 70.6 ± 5.1 y - BMI: 26.9 ± 4.2 kg/m2	RCT	MF-BIA, Hydra ECF/ICF Model 4200 (Xitron Technologies, USA)	- Supine position for 5 min - Euhydration confirmed by post-voiding first-morning body weights and urine color	FOX, AOCC, and CAT	Int: 5.4 ± 0.6° / 560.3 ± 56.1 Ω/ 53.3 ± 7.9 Ω; Ctr: 5.6 ± 0.5° / 579.8 ± 71.5 Ω / 57.0 ± 9.8 Ω	Unadjusted analysis: Correlation between changes in PhA and changes in oxidative stress markers: FOX (r = − 0.43); AOPP (r = − 0.55); CAT (r = 0.73) Adjusted analysis: AOPP (β = −1.84); CAT (β = 2.03)	< 0.01	Negative correlation with AOPP and positive correlation with CAT	Skeletal muscle and body fat
Tomeleri et al., 2018 [83] Brazil	- N = 155 ♀ - Older women - Age: 67.7 ± 5.7 y - BMI: 27.0 ± 4.4 kg/m2 - 75% of women had up to two diseases	Cross-sectional	MF-BIA, Hydra ECF/ICF 4200 (Xitron Technologies, USA)	- Supine position - Voided bladder 30 min prior test - Fasting for 4 h prior test - No strenuous exercise for 24 h - No alcohol/ caffeinated drinks for 48 h prior test - Euhydration confirmed by post-voiding first-morning body weights and urine color - Metals removed - Exam table isolated from electrical conductors - BIA calibrated	CAT, SOD and TRAP	5.7 ± 0.6° / NR / NR	Partial correlations: CAT (r = 0.48); SOD (r = 0.31) and TRAP (r = 0.30)	< 0.01	Positive correlation with CAT, SOD and TRAP	Age, trunk fat mass, appendicular lean soft tissue, and comorbidities
Venancio et al., 2021 [90] Brazil	- N = 39 (32 ♀) - Patients undergoing bariatric surgery - Age range: 18 − 60 y - BMI: ≥35 kg/m2 - Diabetes: 41% - Hypertension: 61.5% - Dyslipidemia: 40.9%	Cohort study	SF-BIA, Biodynamics 450, (Biodynamics® Corp., USA)	- As described for Kyle et al. [97]	AOPP	Median at baseline: RYGB = 7.0 (6.6–7.5)° / 410.6 (339.2–455.9) Ω / 49.9 (42.9–57.8) Ω; SG = 6.9 (6.6–7.2)° / 465.8 (456.0–517.2) Ω / 55.6 (51.7–61.0) Ω	Correlations between changes in PhA and AOPP: r = − 0.549	0.041	Negative correlation with AOPP	NR

Age, body mass index, and phase angle values are mean ± SD, unless otherwise specified. Abbreviations: (−), without; (+), with; ♀, female; ♂, male; AOPP, advanced oxidation protein products; BIA, bioelectrical impedance analysis; BMI, body mass index; CAT, catalase; CKD, chronic kidney disease; CRP, C-reactive protein; Ctr, control group; CVD, cardiovascular disease; eGFR, estimated glomerular filtration rate; FOX, ferrous oxidation-xylenol orange; HD, hemodialysis; ICU, intensive care unit; IL-10, Interleukin 10; IL-6, Interleukin-6; IL 1-β, interleukin 1-β; Int, intervention group; IQR, interquartile range; MF-BIA, multi-frequency bioelectrical impedance analysis; MIS, malnutrition inflammation score; MUS: medically unexplained symptoms; N, sample size; NR, not reported; OB, obesity; OR, odd ratio; OW, overweight; PD, peritoneal dialysis; PhA, phase angle; R, resistance; RCT, randomized controlled trial; RYGB, roux-en-y gastric bypass; SF-BIA: single-frequency bioelectrical impedance analysis; SG, sleeve gastrectomy; SGA, Subjective Global Assessment; SOD, superoxide dismutase; SOFA, Sequential Organ Failure Assessment; TAC, total antioxidant capacity; TNF-α, tumor necrosis factor‐α; TRAP, radical-trapping antioxidant potential; Xc, reactance