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

In the paper

“Both weighted and unweighted meta-analyses detected a significantly higher antioxidant activity in organic crops (Fig. 3) and the MPD was 17 (95 % CI 3, 32) % (Fig. 3).”

In the paper

“Also, lower concentrations of Mn ( − 8 (95 % CI − 13, − 3) %) and higher concentrations of Ga and Mg in organic crops (57 (95 % CI − 122, 8) % and 4 (95 % CI − 5, 13) %, respectively) were detected only by the weighted meta-analysis, while slightly higher concentrations of Zn (5 (95 % CI − 6, 15) %) in organic crops were only detected by the unweighted meta-analysis (see online supplementary Table”

In the paper

“The MPD were 17 (95 % CI 0, 34) % for total carotenoids, 15 (95 % CI − 3, 32) % for carotenoids (where data reported for all individual carotenoid compounds were included in the same analysis), 12 (95 % CI − 4, 28) % for xanthophylls, 5 (95 % CI − 3, 13) % for lutein, 6 (95 % CI − 3, 15) % for vitamin C and − 15 (95 % CI − 49, 19) % for vitamin E.”

In the paper

“When data reported for total carotenoids and xanthophylls in fruits, vegetables, cereals and processed crop-based compound foods were analysed separately, significantly higher concentrations in organic samples were detected only for fruits (Fig. 4), with evidence of interactions being detected for carotenoids, but not for xanthophylls.”

In the paper

“for the ferric reducing antioxidant power and oxygen radical absorbance capacity assays with only the standard unweighted meta-analysis”

In the paper

“Higher concentrations of total carotenoids, carotenoids (where data reported for all individual phenolic acid compounds were included in the same analysis) and lutein were also detected by the unweighted meta-analysis (Fig. 3).”

In the paper

“However, for a small number of minerals, differences in composition were identified by both weighted and unweighted meta-analyses, which detected significantly lower concentrations of Cr and Sr ( − 59 (95 % CI − 147, 30) % and − 26 (95 % CI − 45, − 6) %, respectively), but significantly higher concentrations of Mo and Rb (65 (95 % CI 26, 105) % and 82 (95 % CI 6, 157) %, respectively) in organic”

In the paper

“The MPD were − 48 (95 % CI − 112, 16) % for Cd, − 10 (95 % CI − 15, − 4) % for N, − 30 (95 % CI − 144, 84) % for and − 87 (95 % CI − 225, 52) % for (Fig. 3).”

In the paper

“When data reported for phenolic compounds, phenolic acids and flavanones in fruits, vegetables, cereals and/or processed crop-based foods were analysed separately, significant differences were detected only for the concentrations of phenolic compounds and phenolic acids in fruits and a trend towards a significant difference (P= 0·09) was detected for the concentrations of flavanones in fruits (Fig”

In the paper

“In contrast, when differences in the concentrations of flavones and flavonols were analysed separately for fruits, vegetables and cereals, significant differences were detected for vegetables and cereals, but not for fruits, with evidence of interactions (Fig. 4).”

In the paper

“Inclusion of data for which no measures of variance were reported in the calculation of MPD yielded similar values for phenolic compounds, phenolic acids, chlorogenic acid, flavones, quercetin, kaempferol and anthocyanins; higher values for phenolic acids (total), stilbenes and quercetin-3-rutinoside; and lower values for flavonoids, flavanones and flavonols (see Fig. 4 and online supplementary”

In the paper

“The MPD were 25 (95 % CI 5, 45) % for total carbohydrates, 11 (95 % CI 2, 20) % for carbohydrates (where data reported for all individual phenolic acid compounds were included in the same analysis), 7 (95 % CI 4, 11) % for reducing sugars, − 15 (95 % CI − 27, − 3) % for proteins, − 11 (95 % CI − 14, − 8) % for amino acids, 2 (95 % CI − 1, 6) % for DM and − 8 (95 % CI − 14, − 2) % for fibre.”

In the paper

“Both unweighted and weighted meta-analyses detected significantly higher concentrations of xanthophylls and l-ascorbic acid and significantly lower concentrations of vitamin E in organic crops.”

In the paper

“Both weighted and unweighted meta-analyses detected significantly lower concentrations of the toxic metal Cd and total N in organic crops, while lower concentrations of and in organic crops were detected only by the unweighted meta-analysis (Fig. 3).”

In the paper

“When data reported for proteins and amino acids in vegetables, cereals and/or processed crop-based foods were analysed separately, significant differences were detected for cereals and processed crop-based foods, but not for vegetables (Fig. 4), although there was no evidence of an interaction.”

In the paper

“Conventional fruits had a higher frequency (75 (95 % CI 65, 85) %) of occurrence of pesticide residues than vegetables (32 (95 % CI 22, 43) %) and crop-based compound foods (45 (95 % CI 25, 65) %), while contamination rates were very similar in the different organic crop types. This resulted in significant differences in the OR for different crop types (Fig. 5).”

In the paper

“When data reported for N and Cd concentrations in fruits, vegetables and cereals were analysed separately, significant differences were detected for cereals, but not for vegetables and/or fruits (Fig. 4), although there was no evidence of an interaction.”

In the paper

“Both unweighted and weighted meta-analyses detected significantly higher concentrations of total carbohydrates and significantly lower concentrations of proteins, amino acids and fibre in organic crops/crop-based compound foods (Fig. 3).”

In the paper

“The unweighted meta-analysis yielded similar results, except for (1) total flavonoids, for which no significant difference was detected, and (2) flavanones and flavones, for which only trends towards higher concentrations in organic crops were detected (Fig. 3).”

In the paper

“similar results were obtained for the Trolox equivalent antioxidant capacity assay with both the standard weighted and unweighted meta-analyses”

In the paper

“In contrast to previous literature reviews( 19 – 21 ), the larger number of studies now available allowed separate meta-analyses to be carried out for different crop types (e.g. fruits, vegetables and cereals), but only for a limited number of composition parameters.”

What the sources say

• Not checked yetcites [19] Dangour AD, Dodhia SK, Hayter A, et al. (2009) Nutritional quality of organic foods: a systematic review. Am J Clin Nutr 90, 680– 685 19640946 source
• Not checked yetcites [20] Brandt K, Leifert C, Sanderson R, et al. (2011) Agroecosystem management and nutritional quality of plant foods: the case of organic fruits and vegetables. Crit Rev Plant Sci 30, 177– 197 source
• Not checked yetcites [21] Smith-Spangler C, Brandeau ML, Hunter GE, et al. (2012) Are organic foods safer or healthier than conventional alternatives? A systematic review. Ann Intern Med 157, 348– 366 22944875 source

In the paper

“Overall assessment of the strength of evidence for antioxidant/(poly)phenolic parameters indicated high or moderate reliability for thirteen of the nineteen parameters and moderate reliability for Cd.”

In the paper

“Particularly, there is a lack of studies comparing pesticide residue levels in organic and conventional crops, and there has been very little effort taken to re-analyse and then publish available comparative data from food surveillance surveys (e.g. the regular pesticide residue and food composition surveys carried out by the European Food Safety Authority and national agencies in Europe and”

In the paper

“The present study identified deficiencies in a large proportion of the published studies. These included a lack of standardised measurements and a lack of reporting (and, in particular, the non-reporting of measures of variability and/or replication) for many composition parameters, and there was evidence of duplicate or selective reporting of data collected in experiments, which may lead to”

In the paper

“Several systematic literature reviews have recently analysed the available published information, using both qualitative and quantitative methods, with the aim of identifying the potential effects of organic and conventional production protocols on the nutritional quality of crops( 19 – 21 ).”

What the sources say

• Not checked yetcites [19] Dangour AD, Dodhia SK, Hayter A, et al. (2009) Nutritional quality of organic foods: a systematic review. Am J Clin Nutr 90, 680– 685 19640946 source
• Not checked yetcites [20] Brandt K, Leifert C, Sanderson R, et al. (2011) Agroecosystem management and nutritional quality of plant foods: the case of organic fruits and vegetables. Crit Rev Plant Sci 30, 177– 197 source
• Not checked yetcites [21] Smith-Spangler C, Brandeau ML, Hunter GE, et al. (2012) Are organic foods safer or healthier than conventional alternatives? A systematic review. Ann Intern Med 157, 348– 366 22944875 source

In the paper

“As a result, organic and conventional crop production may differ significantly in crop rotation designs and fertilisation and crop protection protocols as well as in the type of crop varieties used( 6 – 10 ).”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [6] Hansen AL (2010) The Organic Farming Manual: A Comprehensive Guide to Starting and Running a Certified Organic Farm. North Adams, MA: Storey Books
• Not checked yetcites [7] Cooper J, Sanderson R, Cakmak I, et al. (2011) Effect of organic and conventional crop rotation, fertilization, and crop protection practices on metal contents in wheat (Triticum aestivum). J Agric Food Chem 59, 4715– 4724 21495704 source
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [8] van Bueren ETL, Jones SS, Tamm L, et al. (2011) The need to breed crop varieties suitable for organic farming, using wheat, tomato and broccoli as examples: a review. NJAS Wageningen J Life Sci 58, 193– 205
• Not checked yetcites [9] Tetard-Jones C, Edwards M, Rempelos L, et al. (2013) Effects of previous crop management, fertilization regime and water supply on potato tuber proteome and yield. Agronomy 3, 59– 85 source
• Not checked yetcites [10] Rempelos L, Cooper J, Wilcockson S, et al. (2013) Quantitative proteomics to study the response of potato to contrasting fertilisation regimes. Mol Breed 31, 363– 378 source

In the paper

“In conclusion, organic crops, on average, have higher concentrations of antioxidants, lower concentrations of Cd and a lower incidence of pesticide residues than the non-organic comparators across regions and production seasons.”

In the paper

“An overall assessment of the strength of evidence was made using an adaptation of the GRADE (Grading of Recommendations, Assessment, Development and Evaluation) system( 41 ).”

What the sources say

• Not checked yetcites [41] Guyatt GH, Oxman AD, Vist GE, et al. (2008) GRADE: an emerging consensus on rating quality of evidence and strength of recommendations. BMJ 336, 924– 926 18436948 PMC2335261

In the paper

“Weighted meta-analyses are widely regarded as the most appropriate statistical approach for comparing data sets from studies with variable experimental designs( 25 , 26 ).”

What the sources say

• Not checked yetcites [25] Stewart G (2010) Meta-analysis in applied ecology. Biol Lett 6, 78– 81 19776064 PMC2817246 source
• Not checked yetcites [26] Koricheva J & Gurevitch J (2013) Place of meta-analysis among other methods of research synthesis. In Handbook of Meta-Analysis in Ecology and Evolution, [ Koricheva J, Gurevitch J and Mengersen K, editors]. Princeton, NJ: Princeton University Press source

In the paper

“Recent studies have shown that the switch from mineral to organic fertilisers results in significant differences in gene and protein expression patterns and, as a result, in secondary metabolite profiles; for example, approximately 10 % of proteins have been found to be either up- or down-regulated in response to contrasting fertiliser inputs in potato and wheat( 10 – 15 ).”

What the sources say

• Not checked yetcites [10] Rempelos L, Cooper J, Wilcockson S, et al. (2013) Quantitative proteomics to study the response of potato to contrasting fertilisation regimes. Mol Breed 31, 363– 378 source
• Not checked yetcites [11] Lehesranta SJ, Koistinen KM, Massat N, et al. (2007) Effects of agricultural production systems and their components on protein profiles of potato tubers. Proteomics 7, 597– 604 17309105 source
• Not checked yetcites [12] Tetard-Jones C, Shotton PN, Rempelos L, et al. (2013) Quantitative proteomics to study the response of wheat to contrasting fertilisation regimes. Mol Breed 31, 379– 393 source
• Not checked yetcites [13] van Dijk JP, Cankar K, Scheffer SJ, et al. (2009) Transcriptome analysis of potato tubers – effects of different agricultural practices. J Agric Food Chem 57, 1612– 1623 19173602 source
• Not checked yetcites [14] van Dijk JP, Leifert C, Barros E, et al. (2010) Gene expression profiling for food safety assessment: examples in potato and maize. Regul Toxicol Pharmacol 58, Suppl. 3, S21– S25 20600454 source
• Not checked yetcites [15] van Dijk JP, Cankar K, Hendriksen PJM, et al. (2012) The identification and interpretation of differences in the transcriptomes of organically and conventionally grown potato tubers. J Agric Food Chem 60, 2090– 2101 22300527 source

In the paper

“However, these systematic reviews (1) used different methodologies (e.g. weighted and unweighted meta-analyses) and inclusion criteria, (2) did not cover most of the large amount of information published in the last 4–5 years, (3) provided no structured assessment of the strength of the evidence presented, and (4) came to contrasting conclusions.”

What the sources say

• Not checked yetcites [19] Dangour AD, Dodhia SK, Hayter A, et al. (2009) Nutritional quality of organic foods: a systematic review. Am J Clin Nutr 90, 680– 685 19640946 source
• Not checked yetcites [20] Brandt K, Leifert C, Sanderson R, et al. (2011) Agroecosystem management and nutritional quality of plant foods: the case of organic fruits and vegetables. Crit Rev Plant Sci 30, 177– 197 source
• Not checked yetcites [21] Smith-Spangler C, Brandeau ML, Hunter GE, et al. (2012) Are organic foods safer or healthier than conventional alternatives? A systematic review. Ann Intern Med 157, 348– 366 22944875 source

In the paper

“Data extracted by the two reviewers were then compared. Discrepancies were detected for approximately 2 % of the data extracted, and in these cases, data extraction was repeated to correct mistakes.”

In the paper

“Publications were assessed for eligibility and data were independently extracted from them by two reviewers.”

In the paper

“As a result, there is still considerable controversy as to whether the use of organic production standards results in significant and consistent changes in the concentrations of potentially health-promoting (e.g. antioxidants, (poly)phenolics, vitamins and certain minerals) and potentially harmful (e.g. Cd and Pb) compounds in crops and crop-based foods( 7 , 19 – 22 ).”

What the sources say

• Not checked yetcites [7] Cooper J, Sanderson R, Cakmak I, et al. (2011) Effect of organic and conventional crop rotation, fertilization, and crop protection practices on metal contents in wheat (Triticum aestivum). J Agric Food Chem 59, 4715– 4724 21495704 source
• Not checked yetcites [19] Dangour AD, Dodhia SK, Hayter A, et al. (2009) Nutritional quality of organic foods: a systematic review. Am J Clin Nutr 90, 680– 685 19640946 source
• Not checked yetcites [20] Brandt K, Leifert C, Sanderson R, et al. (2011) Agroecosystem management and nutritional quality of plant foods: the case of organic fruits and vegetables. Crit Rev Plant Sci 30, 177– 197 source
• Not checked yetcites [21] Smith-Spangler C, Brandeau ML, Hunter GE, et al. (2012) Are organic foods safer or healthier than conventional alternatives? A systematic review. Ann Intern Med 157, 348– 366 22944875 source
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [22] Benbrook C, Zhao X, Davies N, et al. (2008) New evidence confirms the nutritional superiority of plant-based organic foods. http://organic-center.org/reportfiles/NutrientContentReport.pdf (accessed June 2014)

In the paper

“However, some studies have used unweighted analytical methods( 19 ) to avoid the loss of information associated with conducting weighted meta-analyses on a subset of the available information.”

What the sources say

• Not checked yetcites [19] Dangour AD, Dodhia SK, Hayter A, et al. (2009) Nutritional quality of organic foods: a systematic review. Am J Clin Nutr 90, 680– 685 19640946 source

In the paper

“Funnel plots, Egger tests of funnel plot asymmetry and fail-safe number tests were used to assess publication bias( 37 )”

What the sources say

• Not checked yetcites [37] Rothstein HR, Sutton AJ & Borenstein M (2006) Publication Bias in Meta-Analysis. Chichester, UK: John Wiley & Sons Ltd source

In the paper

“We carried out tests of homogeneity (Q statistics and I 2 statistics) on all the summary effect sizes.”

In the paper

“There is evidence that higher antioxidant concentrations and lower Cd concentrations are linked to specific agronomic practices (e.g. non-use of mineral N and P fertilisers, respectively) prescribed in organic farming systems.”

In the paper

“Based on the differences reported, results indicate that a switch from conventional to organic crop consumption would result in a 20–40 % (and for some compounds more than 60 %) increase in crop-based antioxidant/(poly)phenolic intake levels without a simultaneous increase in energy, which would be in line with the dietary recommendations( 16 , 17 ).”

What the sources say

• Not checked yetcites [16] Del Rio D, Rodriguez-Mateos A, Spencer JPE, et al. (2013) Dietary (poly)phenolics in human health: structures, bioavailability, and evidence of protective effects against chronic diseases. Antioxid Redox Signal 18, 1818– 1892 22794138 PMC3619154 source
• Not checked yetcites [17] Wahlqvist ML (2013) Antioxidant relevance to human health. Asia Pac J Clin Nutr 22, 171– 176 23635359 source

In the paper

“In addition, most of the previous studies did not use weighted meta-analyses based on SMD.”

In the paper

“The study also demonstrated that composition differences were mainly linked to contrasting fertilisation regimens (green and animal manures v. mineral fertiliser inputs).”

What the sources say

• Not checked yetcites [46] Srednicka-Tober D, Baranski M, Gromadzka-Ostrowska J, et al. (2013) Effect of crop protection and fertilization regimes used in organic and conventional production systems on feed composition and physiological parameters in rats. J Agric Food Chem 61, 1017– 1029 23323826 source

In the paper

“With respect to composition differences, the study yielded results similar to those of the meta-analyses carried out in the present study. For example, rat feeds produced from organic crops had lower concentrations of proteins and Cd, but higher concentrations of polyphenols and the carotenoid lutein.”

What the sources say

• Not checked yetcites [46] Srednicka-Tober D, Baranski M, Gromadzka-Ostrowska J, et al. (2013) Effect of crop protection and fertilization regimes used in organic and conventional production systems on feed composition and physiological parameters in rats. J Agric Food Chem 61, 1017– 1029 23323826 source

In the paper

“The overall assessment of the strength of evidence using an adapted GRADE( 41 ) approach highlighted uncertainties in the evidence base, but the overall strength of evidence was moderate or high for the majority of parameters for which significant differences were detected (see Table 1 and online supplementary Table S13).”

What the sources say

• Not checked yetcites [41] Guyatt GH, Oxman AD, Vist GE, et al. (2008) GRADE: an emerging consensus on rating quality of evidence and strength of recommendations. BMJ 336, 924– 926 18436948 PMC2335261

In the paper

“However, it is not possible to definitively attribute discrepancies between large precise studies and small imprecise studies to publication bias, which remains strongly suspected rather than detected where asymmetry is severe (see Table 1 and online supplementary Table S13).”

In the paper

“The results of meta-analyses of the extensive data set of 343 peer-reviewed publications indicated that organic crops and processed crop-based foods have a higher antioxidant activity and contain higher concentrations of a wide range of nutritionally desirable antioxidants/(poly)phenolics, but lower concentrations of the potentially harmful, toxic metal Cd.”

In the paper

“There are, to our knowledge, only two human dietary intervention studies in which contrasting antioxidant/(poly)phenolic intake levels were generated by providing diets based on conventional and organic crops; both studies focused on assessing antioxidant status in humans and were inconclusive with respect to the identification of potential health impacts of organic food consumption( 21 , 42 , 43”

What the sources say

• Not checked yetcites [21] Smith-Spangler C, Brandeau ML, Hunter GE, et al. (2012) Are organic foods safer or healthier than conventional alternatives? A systematic review. Ann Intern Med 157, 348– 366 22944875 source
• Not checked yetcites [42] Grinder-Pedersen L, Rasmussen SE, Bügel S, et al. (2003) Effect of diets based on foods from conventional versus organic production on intake and excretion of flavonoids and markers of antioxidative defense in humans. J Agric Food Chem 51, 5671– 5676 12952417 source
• Not checked yetcites [43] Søltoft M, Bysted A, Madsen KH, et al. (2011) Effects of organic and conventional growth systems on the content of carotenoids in carrot roots, and on intake and plasma status of carotenoids in humans. J Sci Food Agric 91, 767– 775 21213256 source

In the paper

“Therefore, higher concentrations of (poly)phenolics in organic crops may be due to higher incidence/severity of pest and disease damage, causing enhanced (poly)phenolic production as part of the inducible plant resistance response.”

In the paper

“In the study carried out by Dangour et al. ( 19 ), published data from (1) surveys in which the organic samples were produced to ‘biodynamic-organic’ standards and (2) field experiments investigating associations between organic and conventional production protocols and crop composition were not included in the meta-analyses. This would have further reduced the number of data sets and sensitivity”

What the sources say

• Not checked yetcites [19] Dangour AD, Dodhia SK, Hayter A, et al. (2009) Nutritional quality of organic foods: a systematic review. Am J Clin Nutr 90, 680– 685 19640946 source

In the paper

“However, it is important to point out that there is still a lack of knowledge about the potential human health impacts of increasing antioxidant/(poly)phenolic intake levels and switching to organic food consumption.”

In the paper

“Similar to the results of the present study, a recent literature review by Smith-Spangler et al. ( 21 ) has also reported that of the seventy-seven comparative data sets (extracted from fifteen publications), twenty-one indicated significantly lower and only one significantly higher Cd concentrations in organic foods.”

What the sources say

• Not checked yetcites [21] Smith-Spangler C, Brandeau ML, Hunter GE, et al. (2012) Are organic foods safer or healthier than conventional alternatives? A systematic review. Ann Intern Med 157, 348– 366 22944875 source

In the paper

“Differences in Cd contamination levels between organic and conventional winter wheat have recently been shown to be mainly linked to differences in fertilisation regimens (especially the high mineral P inputs used in conventional farming systems), although contrasting rotation designs also contributed to differences in Cd concentrations between organic and conventional wheat( 7 ).”

What the sources say

• Not checked yetcites [7] Cooper J, Sanderson R, Cakmak I, et al. (2011) Effect of organic and conventional crop rotation, fertilization, and crop protection practices on metal contents in wheat (Triticum aestivum). J Agric Food Chem 59, 4715– 4724 21495704 source

In the paper

“The higher and concentrations in conventional crops are also thought to be linked to high mineral N inputs, as both and are known to accumulate in plants under high-mineral N input regimens( 65 ).”

What the sources say

• Not checked yetcites [65] McKnight GM, Duncan CW, Leifert C, et al. (1999) Dietary nitrate in man: friend or foe? Br J Nutr 81, 349– 358 10615207 source

In the paper

“Cd accumulates in the human body (especially in the liver and kidneys) and therefore dietary Cd intake levels should be kept as low as possible( 53 ).”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [53] European Commission (2008) Commission Regulation (EC) No. 629/2008 of 2 July 2008 amending Regulation (EC) No. 1881/2006 setting maximum levels for certain contaminants in foodstuffs. Off J Eur Union L 173, 6– 9

In the paper

“This demonstrates that there is variation between crop types with respect to (1) whether the production system has a significant effect and/or (2) the magnitude of difference between organic and conventional crops, although sample sizes remain insufficient to detect interactions between crop types in many cases.”

In the paper

“The higher concentrations in conventional crops/crop-based foods are nutritionally undesirable, as they have been described to be risk factors for stomach cancer and methaemoglobinaemia in humans( 65 ).”

What the sources say

• Not checked yetcites [65] McKnight GM, Duncan CW, Leifert C, et al. (1999) Dietary nitrate in man: friend or foe? Br J Nutr 81, 349– 358 10615207 source

In the paper

“However, care should be taken when interpreting MPD values, as they do not take variability in the precision of individual studies into account( 25 ) and provide less precise estimates of effect than weighted estimates.”

What the sources say

• Not checked yetcites [25] Stewart G (2010) Meta-analysis in applied ecology. Biol Lett 6, 78– 81 19776064 PMC2817246 source

In the paper

“However, while increasing dietary intake levels is widely considered to be potentially harmful for human health, there is still controversy about the potential health impacts of crop-based dietary intake( 65 – 67 ).”

What the sources say

• Not checked yetcites [65] McKnight GM, Duncan CW, Leifert C, et al. (1999) Dietary nitrate in man: friend or foe? Br J Nutr 81, 349– 358 10615207 source
• Not checked yetcites [66] Lundberg JO, Weitzberg E & Gladwin MT (2008) The nitrate–nitrite–nitric oxide pathway in physiology and therapeutics. Nat Rev Drug Discov 7, 156– 167 18167491 source
• Not checked yetcites [67] Machha A & Schechter AN (2012) Inorganic nitrate: a major player in the cardiovascular health benefits of vegetables? Nutr Rev 70, 367– 372 22646129 PMC3367800 source

In the paper

“This is not surprising as both genetic and environmental/agronomic factors are known to affect the concentrations of N, , , proteins, sugars, antioxidants/(poly)phenolics, Cd and pesticides in crops( 7 , 9 – 12 , 20 , 47 – 52 , 62 ).”

What the sources say

• Not checked yetcites [7] Cooper J, Sanderson R, Cakmak I, et al. (2011) Effect of organic and conventional crop rotation, fertilization, and crop protection practices on metal contents in wheat (Triticum aestivum). J Agric Food Chem 59, 4715– 4724 21495704 source
• Not checked yetcites [9] Tetard-Jones C, Edwards M, Rempelos L, et al. (2013) Effects of previous crop management, fertilization regime and water supply on potato tuber proteome and yield. Agronomy 3, 59– 85 source
• Not checked yetcites [10] Rempelos L, Cooper J, Wilcockson S, et al. (2013) Quantitative proteomics to study the response of potato to contrasting fertilisation regimes. Mol Breed 31, 363– 378 source
• Not checked yetcites [11] Lehesranta SJ, Koistinen KM, Massat N, et al. (2007) Effects of agricultural production systems and their components on protein profiles of potato tubers. Proteomics 7, 597– 604 17309105 source
• Not checked yetcites [12] Tetard-Jones C, Shotton PN, Rempelos L, et al. (2013) Quantitative proteomics to study the response of wheat to contrasting fertilisation regimes. Mol Breed 31, 379– 393 source
• Not checked yetcites [20] Brandt K, Leifert C, Sanderson R, et al. (2011) Agroecosystem management and nutritional quality of plant foods: the case of organic fruits and vegetables. Crit Rev Plant Sci 30, 177– 197 source
• Not checked yetcites [47] Nicholson RL & Hammerschmidt R (1992) Phenolic compounds and their role in disease resistance. Annu Rev Phytopathol 30, 369– 389 source
• Not checked yetcites [48] Bennett RN & Wallsgrove RM (1994) Secondary metabolites in plant defense mechanisms. New Phytol 127, 617– 633 33874382 source
• Not checked yetcites [49] Almuayrifi M (2013) Effect of fertilisation, crop protection, pre-crop and variety choice on yield of phenols content diseases severity and yield of winter wheat. PhD Thesis, Newcastle University.
• Not checked yetcites [50] Sander JF & Heitefuss R (1998) Susceptibility to Erysiphe graminis f. sp. tritici and phenolic acid content of wheat as influenced by different levels of nitrogen fertilization. J Phytopathol 146, 495– 507 source

In the paper

“There is still scientific controversy about the safety of some currently permitted pesticides (e.g. organophosphorus compounds) even at levels below the MRL and complex mixtures of pesticides, as additive/synergistic effects of pesticide mixtures have been documented and safety testing of pesticide mixtures is currently not required as part of the regulatory pesticide approval process( 58 – 60 ).”

What the sources say

• Not checked yetcites [58] Marinovich M, Ghilardi F & Galli CL (1996) Effect of pesticide mixtures on in vitro nervous cells: comparison with single pesticides. Toxicology 108, 201– 206 8658539 source
• Not checked yetcites [59] Pape-Lindstrom PA & Lydy MJ (1997) Synergistic toxicity of atrazine and organophosphate insecticides contravenes the response addition mixture model. Environ Toxicol Chem 16, 2415– 2420 source
• Not checked yetcites [60] Axelrad JC, Howard CV & McLean WG (2002) Interactions between pesticides and components of pesticide formulations in an in vitro neurotoxicity test. Toxicology 173, 259– 268 11960678 source

In the paper

“Pesticide residues that are below the MRL set by the European Commission( 55 , 56 ) are considered by regulators not to pose risk to consumers or the environment, as they are significantly lower than concentrations for which negative health or environmental impacts can be detected in the regulatory pesticide safety testing carried out as part of the pesticide approval process( 55 ).”

What the sources say

• Not checked yetcites [55] European Commission (2005) Commission Regulation (EC) No. 396/2005 of 23 February 2005 on maximum residue levels of pesticides in or on food and feed of plant and animal origin and amending Council Directive 91/414/EEC. Off J Eur Union L 70, 1– 16
• Not checked yetcites [56] European Food Safety Authority (2013) Maximum Residue Levels http://www.efsa.europa.eu/en/pesticides/mrls.htm (accessed accessed September 2013).

In the paper

“The nutritional significance/relevance of slightly lower protein and amino acid concentrations in organic crops to human health is likely to be low, as European and North American diets typically provide sufficient or even excessive amounts of proteins and essential amino acids.”

• Also stated in: § Proteins, amino acids, nitrogen and nitrate/nitrite · hedged

  “Therefore, the lower protein and amino acid concentrations found in organic foods are unlikely to have a significant nutritional or health impact.”

In the paper

“The concentrations of proteins, amino acids and N (which are known to be positively correlated in plants) were found to be lower in organic crops, and this is consistent with the results of previous studies that have linked lower protein concentrations to lower N inputs and N availability in organic crop production systems( 61 , 62 ).”

What the sources say

• Not checked yetcites [61] Lueck L, Schmidt C, Cooper J, et al. (2006) Effect of organic, low-input and conventional production systems on yield and quality of winter wheat. Aspects Appl Biol 80, 135– 140 source
• Not checked yetcites [62] Bilsborrow P, Cooper J, Tetard-Jones C, et al. (2013) The effect of organic and conventional crop production systems on the yield and quality of wheat (Triticum aestivum) grown in a long-term field trial. Eur J Agron 51, 71– 80 source

In the paper

“The considerably higher frequency of occurrence of detectable residues in conventional fruits (75 %) than in vegetables (32 %) may indicate higher levels of crop protection inputs being used in fruit crops, but could also have been due to the use of more persistent chemicals, different sprayer technologies used and/or pesticide applications being made closer to harvest.”

In the paper

“This supports previous studies that have concluded that organic food consumption can reduce exposure to pesticide residues( 21 – 23 ).”

What the sources say

• Not checked yetcites [21] Smith-Spangler C, Brandeau ML, Hunter GE, et al. (2012) Are organic foods safer or healthier than conventional alternatives? A systematic review. Ann Intern Med 157, 348– 366 22944875 source
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [22] Benbrook C, Zhao X, Davies N, et al. (2008) New evidence confirms the nutritional superiority of plant-based organic foods. http://organic-center.org/reportfiles/NutrientContentReport.pdf (accessed June 2014)
• Not checked yetcites [23] Curl C, Fenske RA & Elgethun K (2003) Organophosphorus pesticide exposure of urban and suburban preschool children with organic and conventional diets. Environ Health Perspect 111, 377– 382 12611667 PMC1241395 source

In the paper

“For example, in recent European Food Safety Authority surveys, pesticide residues above the MRL have been found in 6·2 % of spinach, 3·8 % of oat, 3·4 % of peach, 3·0 % of orange, 2·9 % of strawberry and lettuce, 2·8 % of table grape and 2·7 % of apple samples analysed( 57 ).”

What the sources say

• Not checked yetcites [57] European Food Safety Authority (2011) The 2009 European Union report on pesticide residues in food. EFSA 9, 2430 source

In the paper

“A range of other soil (e.g. pH) and agronomic (e.g. liming) factors are known to affect Cd concentrations in crops( 54 ), and these may explain the variability in results between individual comparative studies, crop species and crop types (see Fig. 4 and online supplementary Figs. S4 and S22).”

What the sources say

• Not checked yetcites [54] Bešter PK, Lobnik F, Eržen I, et al. (2013) Prediction of cadmium concentration in selected home-produced vegetables. Ecotoxicol Environ Saf 96, 182– 190 23886800 source

In the paper

“This supports the conclusion that future research would likely be confirmatory.”

In the paper

“Cd is a highly toxic metal and one of the only three toxic metal contaminants (the other two being Pb and Hg) for which the European Commission has set maximum residue levels (MRL) in foods( 53 ).”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [53] European Commission (2008) Commission Regulation (EC) No. 629/2008 of 2 July 2008 amending Regulation (EC) No. 1881/2006 setting maximum levels for certain contaminants in foodstuffs. Off J Eur Union L 173, 6– 9

In the paper

“However, they concluded that the currently available data do not allow clear trends with respect to health markers and outcomes to be identified.”

What the sources say

• Not checked yetcites [21] Smith-Spangler C, Brandeau ML, Hunter GE, et al. (2012) Are organic foods safer or healthier than conventional alternatives? A systematic review. Ann Intern Med 157, 348– 366 22944875 source

In the paper

“Diet composition may have an effect on the relative impact of switching from conventional to organic food consumption, and this should be considered in the design of such studies.”

In the paper

“A recent review by Smith-Spangler et al. ( 21 ) has analysed the results of fourteen studies in which the effects of organic and conventional food (both crop and livestock product) consumption on clinical outcomes (e.g. allergic symptoms and Campylobacter infections) and health markers (e.g. serum lipid and vitamin concentrations) were studied.”

What the sources say

• Not checked yetcites [21] Smith-Spangler C, Brandeau ML, Hunter GE, et al. (2012) Are organic foods safer or healthier than conventional alternatives? A systematic review. Ann Intern Med 157, 348– 366 22944875 source

In the paper

“For example, the relative impact of switching from conventional to organic food consumption could be expected to be smaller for diets with high amounts of (poly)phenolic-rich foods.”

In the paper

“However, there is now evidence from a large number of quality studies that consistently show that organic production systems result in crops/crop-based compound foods with higher concentrations of antioxidants/(poly)phenolics and lower concentrations of Cd and pesticide residues compared with conventional production systems.”