Higher antioxidant and lower cadmium concentrations and lower incidence of
pesticide residues in organically grown crops: a systematic literature review and meta-analyses

doi:10.1017/S0007114514001366

Table 1

GRADE (Grading of Recommendations, Assessments, Development and Evaluation) assessment of the strength of evidence for standard weighted meta-analysis for parameters included in Fig. 3 (Standardised mean difference values (SMD) and 95 % confidence intervals)

Parameters	SMD	95 % CI	Effect magnitude^*	Inconsistency^†	Precision^‡	Publication bias^§	Overall reliability
Antioxidant activity	1·11	0·43, 1·79	Moderate	Medium	Poor	None	Moderate
FRAP	0·59	− 0·89, 2·06	Moderate	Low	Poor	Medium	Moderate
ORAC	1·92	− 0·86, 4·71	Large	Low	Poor	Strong	Low
TEAC	0·25	0·02, 0·48	Small	Medium	High	Medium	Good
Phenolic compounds (total)	0·52	0·00, 1·05	Small	Medium	Moderate	None	Moderate
Flavonoids (total)	1·64	0·09, 3·19	Large	Medium	Poor	Medium	Moderate
Phenolic acids (total)	0·81	0·18, 1·44	Small	Low	Moderate	Strong	Low
Phenolic acids^∥	0·59	0·11, 1·07	Small	Medium	Moderate	None	Moderate
Chlorogenic acid	1·58	− 0·32, 3·49	Large	High	Poor	Medium	Low
Flavanones^∥	4·76	0·54, 8·98	Large	Medium	Moderate	None	Moderate
Stilbenes	0·74	0·19, 1·28	Small	Low	Moderate	Medium	Moderate
Flavones and flavonols	1·74	1·21, 2·28	Large	Medium	High	None	Good
Flavones	0·95	0·39, 1·51	Moderate	Medium	Moderate	None	Moderate
Flavonols^∥	1·97	1·31, 2·64	Large	Medium	High	None	Good
Quercetin	0·55	− 0·58, 1·69	Small	Low	Poor	Medium	Low
Rutin	1·10	− 0·31, 2·50	Moderate	Medium	Poor	None	Low
Kaempferol	1·34	0·19, 2·50	Moderate	Low	Poor	None	Low
Anthocyanins (total)	1·60	0·59, 2·62	Large	Low	Moderate	Medium	Moderate
Anthocyanins	3·81	1·53, 6·09	Large	Medium	High	Medium	Moderate
Carotenoids (total)	7·98	− 6·22, 22·18	Large	Medium	Poor	Strong	Low
Carotenoids^∥	0·47	− 0·13, 1·07	Small	Medium	Poor	None	Low
Xanthophylls^∥	1·06	0·18, 1·94	Moderate	Medium	Poor	Medium	Low
Lutein	0·51	− 0·27, 1·29	Small	Medium	Poor	Medium	Low
Ascorbic acid	0·33	0·06, 0·60	Small	Medium	Moderate	None	Moderate
Vitamin E	− 0·23	− 0·46, 0·00	Small	Low	Moderate	None	Moderate
Carbohydrates (total)	1·54	0·10, 2·99	Large	Low	Poor	Medium	Low
Carbohydrates^∥	0·46	0·00, 0·91	Small	Medium	Moderate	None	Moderate
Sugars (reducing)	0·21	− 0·23, 0·65	Small	Low	Moderate	None	Moderate
Protein (total)	− 3·01	− 5·18, − 0·84	Large	Medium	Moderate	Medium	Moderate
Amino acids^∥	− 0·82	− 1·14, − 0·50	Small	Medium	High	Medium	Moderate
DM^∥	1·31	− 0·65, 3·28	Moderate	Medium	Poor	Medium	Low
Fibre	− 0·42	− 0·76, − 0·07	Small	Low	Moderate	None	Moderate
N	− 0·88	− 1·59, − 0·17	Moderate	Low	Moderate	Medium	Low
^∥	− 0·50	− 1·73, 0·73	Small	Medium	Poor	Medium	Low
	− 0·11	− 0·38, 0·16	Small	Low	High	None	Moderate
Cd	− 1·45	− 2·52, − 0·39	Moderate	Medium	Moderate	Medium	Moderate

FRAP, ferric reducing antioxidant potential; ORAC, oxygen radical absorbance capacity; TEAC, Trolox equivalent antioxidant capacity.

^*Study quality was considered low because of high risks of bias and potential for confounding. However, we considered large effects to mitigate this sensu GRADE; large effects were defined as >20 %, moderate effects as 10–20 % and small as < 10 %.

^†Inconsistency was based on the measure of heterogeneity and the consistency of effect direction sensu GRADE.

^‡Precision was based on the width of the pooled effect CI and the extent of overlap in the substantive interpretation of effect magnitude sensu GRADE.

^§Publication bias was assessed using visual inspection of funnel plots, Egger tests, two fail-safe number tests, and trim and fill (see online supplementary Table S13). Overall publication bias was considered high when indicated by two or more methods, moderate when indicated by one method, and low when indicated by none of the methods. The overall quality of evidence was then assessed across domains as in standard GRADE appraisal.

^∥Outlying data pairs (where the mean percentage difference between the organic and conventional food samples was over fifty times higher than the mean value including outliers) were removed.