. 2019 May 24;22(15):2823–2834. doi: 10.1017/S1368980019001125

Table 1.

Characteristics of observational studies included in the current systematic review and meta-analysis on dietary acid load and cardiometabolic risk factors

Study	Design	Country	Number of participants	Age range (years)	Gender	DAL assessment method	Dietary intake assessment tool	Outcome	Comparison	NOS score
Wright et al. (2005)⁽¹⁷⁾	Cohort	Finland	27 096 Q5 & Q1: 5419	50–69	M	NAE	24 h urine collection	BMI	Q5 v. Q1	9
Welch et al. (2007)⁽³¹⁾ ^*	Cross-sectional	UK	6375 Q5 & Q1: 1275	42–82	M	PRAL	FFQ	BMI	Q5 v. Q1	6
Welch et al. (2007)⁽³¹⁾ ^*	Cross-sectional	UK	8188 Q5: 1639 Q1: 1640	42–82	F	PRAL	FFQ	BMI	Q5 v. Q1	6
Murakami et al. (2008)⁽¹²⁾	Cross-sectional	Japan	1136 Q5 & Q1: 227	18–22	F	PRAL	DHQ	BMI, WC, SBP, DBP, TC, HDL-C, LDL-C, TAG, FBS, HbA1c	Q5 v. Q1	5
Wynn et al. (2008)⁽³²⁾	Cross-sectional	Switzerland	256 T3: 86 T1: 92	≥70	F	NEAP	FFQ	BMI	T3 v. T1	5
Zhang et al. (2009)⁽¹⁸⁾	Cohort	USA	87 293 D10 & D1: 8729	32–40	F	NEAP	FFQ	BMI	D10 v. D1	7
Scialla et al. (2011)⁽³³⁾	Cross-sectional	USA	462 Q4: 86 Q1: 85	50–72	M	NEAP	24 h urine collection	BMI	Q4 v. Q1	7
Berg et al. (2012)⁽³⁴⁾	Cross-sectional	Netherlands	707 T3 & T1: 236	≥18	Both	NAE	24 h urine collection	SBP, DBP, TC, HDL-C, TAG, HbA1c	T3 v. T1	7
Engberink et al. (2012)⁽⁶⁾	Cohort	Netherlands	2241 T3 & T1: 747	≥55	Both	PRAL	FFQ	BMI, SBP, DBP, TC, HDL-C	T3 v. T1	7
Scialla et al. (2012)⁽¹⁹⁾	Cohort	USA	632 Q4 & Q1: 185	22–70	Both	NEAP	24 h urine collection	BMI	Q4 v. Q1	6
Amodu and Abramowitz (2013)⁽³⁵⁾	Cross-sectional	USA	9781 Q4: 2490 Q1: 2477	≥20	Both	NEAP	24 h recall	BMI	Q4 v. Q1	7
Krupp et al. (2013)⁽³⁶⁾	Cross-sectional	Germany	267 T3 & T1: 89	4–14	Both	PRAL	3 d dietary record	SBP	T3 v. T1	7
Krupp et al. (2013)⁽²⁰⁾	Cohort	Germany	257	4–10	Both	PRAL, NAE	7 d dietary record	SBP, DBP	T3 v. T1	7
Bahadoran et al. (2015)⁽³⁷⁾	Cross-sectional	Iran	5620 Q4 & Q1: 351	20–70	Both	PRAL	FFQ	BMI, weight, WC, SBP, DBP, TAG, FBS	Q4 v. Q1	7
Fagherazzi et al. (2014)⁽²¹⁾	Cohort	France	66 485 Q4: 16 621 Q1: 16 622	44–59	F	PRAL	DHQ	BMI	Q4 v. Q1	6
Xu et al. (2014)⁽¹³⁾	Cohort	Sweden	911 T3: 304 T1: 303	70–71	M	PRAL	7 d dietary record	BMI,FBS	T3 v. T1	7
Akter et al. (2015)⁽³⁸⁾	Cross-sectional	Japan	2028 T3 & T1: 676	18–70	Both	PRAL	DHQ	BMI	T3 v. T1	9
Chan et al. (2015)⁽²²⁾	Cohort	China	3122 Q4: 780 Q1: 779	≥65	Both	NEAP	FFQ	BMI	Q4 v. Q1	8
Garcia et al. (2015)⁽²³⁾ ^*	Cohort	Netherlands	2850 T3 & T1: 950	27–36	F	PRAL	FFQ	BMI	T3 v. T1	8
Garcia et al. (2015)⁽²³⁾ ^*	Cohort	Netherlands	2850 T3 & T1: 950	1–6	Both	PRAL	FFQ	BMI	T3 v. T1	8
Haghighatdoost et al. (2015)⁽¹¹⁾	Cross-sectional	Iran	547 High: 274 Low: 273	50–70	Both	PRAL	FFQ	BMI, WC, SBP, TC, LDL-C, TAG, FBS, HbA1c, HOMA-IR, insulin	High v. Low group	7
Huston et al. (2015)⁽³⁹⁾	Cross-sectional	USA	16 906 Q4: 4616 Q1: 3804	≥17	Both	NEAP	24 h recall	BMI	Q4 v. Q1	7
Iwase et al. (2015)⁽⁴⁰⁾	Cross-sectional	Japan	149 High: 75 Low: 74	≥50	Both	PRAL	DHQ	BMI, SBP, LDL-C, TAG, HbA1c	High v. Low group	4
Jia et al. (2015)⁽²⁴⁾	Cohort	Sweden	861 Q4 & Q1: 215	70	Both	NEAP	7 d FFQ	BMI	Q4 v. Q1	6
Luis et al. (2015)⁽⁴³⁾	Cross-sectional	Sweden	673 T3 & T1: 224	70–71	M	PRAL	7 d dietary record	BMI, SBP, DBP	T3 v. T1	8
Akter et al. (2016)⁽¹⁾	Cross-sectional	Japan	1732 Q4 & Q1: 433	19–69	Both	PRAL	DHQ	BMI, FBS, HbA1c, insulin, HOMA-IR	Q4 v. Q1	7
Akter et al. (2016)⁽²⁵⁾ ^*	Cohort	Japan	27 809 Q4: 6952 Q1: 6953	45–75	M	PRAL	FFQ	BMI	Q4 v. Q1	8
Akter et al. (2016)⁽²⁵⁾ ^*	Cohort	Japan	36 851 Q4: 9212 Q1: 9213	45–75	Female	PRAL	FFQ	BMI	Q4 v. Q1	8
Esche et al. (2016)⁽²⁶⁾	Cohort	Germany	200 High & Low: 100	6–10	Both	NAE	24 h urine collection	BMI, weight	High v. Low group	8
Han et al. (2016)⁽⁴¹⁾	Cross-sectional	Korea	11 601 T3: 4202 T1: 3859	40–79	Both	PRAL	24 h recall	BMI, WC, SBP, DBP, TC, HDL-C, LDL-C, TAG, FBS	T3 v. T1	7
Ikizler et al. (2016)⁽⁴²⁾	Cross-sectional	USA	63 T3 & T1: 21	45–75	Both	NEAP	3 d prospective food dairies	BMI, SBP, DBP, FBS, insulin	T3 v. T1	3
Moghadam et al. (2016)⁽²⁷⁾	Cohort	Iran	925 Q4 & Q1: 231	22–80	Both	PRAL	FFQ	Weight, SBP, DBP, HDL-C, LDL-C, TAG, FBS, HOMA-IR, insulin	Q4 v. Q1	8
Scialla et al. (2016)⁽²⁸⁾	Cohort	USA	980 Q4: 246 Q1: 245	45–75	Both	NAE	24 h urine collection	BMI	Q4 v. Q1	6
Xu et al. (2016)⁽²⁹⁾ ^*	Cohort	Sweden	44 957 Q5: 9038 Q1: 8974	45–84	M	PRAL	FFQ	BMI	Q5 v. Q1	8
Xu et al. (2016)⁽²⁹⁾ ^*	Cohort	Sweden	36 740 Q5 & Q1: 7294	45–84	F	PRAL	FFQ	BMI	Q5 v. Q1	8
Akter et al. (2017)⁽³⁰⁾	Cohort	Japan	92 478 Q4: 23 119 Q1: 23 120	45–75	Both	PRAL	FFQ	BMI	Q4 v. Q1	7
Shea et al. (2017)⁽⁴⁴⁾ ^*	Cross-sectional	USA	162 T3: 13 T1: 19	50–58	Both	NAE	FFQ	BMI	T3 v. T1	6
Shea et al. (2017)⁽⁴⁴⁾ ^*	Cross-sectional	USA	232 T3: 25 T1: 84	60–58	Both	NAE	24 h recall	BMI	T3 v. T1	6

DAL, dietary acid load; NOS, Newcastle–Ottawa Scale; Q, quintile or quartile; T, tertile; D, decile; M, male; F, female; NAE, net acid excretion; PRAL, potential renal net acid load; NEAP, net endogenous acid production; DHQ, diet history questionnaire; WC, waist circumference; SBP, systolic blood pressure; DBP, diastolic blood pressure; TC, total cholesterol; HDL-C, HDL-cholesterol; LDL-C, LDL-cholesterol; FBS, fasting blood sugar; HbA1c, glycated Hb; HOMA-IR, homeostatic model assessment of insulin resistance.

indicates consecutive studies by the same authors that come from just one article but with different situations, such as difference in gender or type of outcome assessed.