Association between iron metabolism and non-alcoholic fatty liver disease: results from the National Health and Nutrition Examination Survey (NHANES 2017–2018) and a controlled animal study

Table 2 Adjusted ORs for associations between iron metabolism and the prevalence of NAFLD

Iron metabolism	Model 1		Model 2		Model 3
Iron metabolism	OR (95%CI)	P for trend	OR (95%CI)	P for trend	OR (95%CI)	P for trend
SI (µg/dl)		< 0.001		< 0.001		0.213
Q1(< 63.00)	1.00		1.00		1.00
Q2 (63.00–84.00)	0.676 (0.450, 0.915)*		0.836 (0.713, 0.981)*		1.007 (0.844, 1.203)
Q3 (84.01–108.00)	0.621 (0.505, 0.765)***		0.762 (0.647, 0.897)***		0.994 (0.825, 1.197)
Q4 (> 108.00)	0.378 (0.272, 0.526)***		0.532 (0.448, 0.632)***		0.842 (0.688, 1.030)
SF (µg/l)		0.239		0.530		0.616
Q1 (< 42.50)	1.00		1.00		1.00
Q2 (42.50–93.30)	0.973 (0.823, 1.149)		1.022 (0.862, 1.211)		1.093 (0.905, 1.320)
Q3 (93.31–179.00)	0.916 (0.769, 1.092)		1.000 (0.836, 1.196)		1.026 (0.837, 1.258)
Q4 (> 179.00)	0.838 (0.696, 1.008)		0.905 (0.749, 1.095)		0.973 (0.779, 1.214)
TSAT (%)		< 0.001		< 0.001		0.002
Q1 (< 19.00)	1.00		1.00		1.00
Q2 (19.00–26.00)	0.751 (0.642, 0.878)***		0.789 (0.672, 0.925)**		0.905 (0.758, 1.079)
Q3 (26.01–34.00)	0.715 (0.609, 0.839)***		0.785 (0.666, 0.925)**		0.987 (0.821, 1.186)
Q4 (> 34.00)	0.433 (0.363, 0.516) ***		0.480 (0.401, 0.575) ***		0.706 (0.575, 0.868) **
sTfR (mg/L)		< 0.001		< 0.001		0.453
Q1 (< 2.49)	1.00		1.00		1.00
Q2 (2.49–2.99)	1.116 (0.989, 1.376)		1.121 (0.947, 1.328)		1.031 (0.961, 1.235)
Q3 (3.00–3.68)	1.406 (1.191, 1.652)***		1.291 (1.092, 1.526)**		1.096 (0.916, 1.312)
Q4 (> 3.68)	1.736 (1.476, 2.042)***		1.523 (1.289, 1.800)***		1.151 (0.955, 1.387)

SI, Serum iron; SF, serum ferritin; TSAT, Transferrin saturation; sTfR, soluble transferrin receptor; NAFLD, non-alcoholic fatty liver disease; Model 1: age and sex. Model 2: Model 1 variables plus race/ethnicity, family poverty-income ratio, marital status, education level, hypertension, diabetes mellitus, smoker, alcohol user. Model 3 was adjusted for Model 2 variables plus body mass index, waist circumference, physical activity, the complication of CHD, CHF, angina pectoris, heart attack, and stroke, mean energy intake, protein intake, folic acid intake, Vitamin B12 intake, Vitamin C intake, Iron intake, high-sensitivity C-reactive protein, glycosylated hemoglobin, alanine aminotransferase, aspartate aminotransferase, gamma-glutamyl transpeptidase, blood urea nitrogen, uric acid, serum creatinine, estimated glomerular filtration rate, urinary albumin creatinine ratio, hemoglobin, high-density lipoprotein-cholesterol, total cholesterol, triglycerides; *P < 0.05, **P < 0.01, ***P < 0.001: All P-values were calculated using Q1 as the reference. P for the trend is presented as the differences between Q1, Q2, Q3 and Q4

ISSN: 1743-7075