Skip to main content Accessibility help

Higher PUFA and n-3 PUFA, conjugated linoleic acid, α-tocopherol and iron, but lower iodine and selenium concentrations in organic milk: a systematic literature review and meta- and redundancy analyses

  • Dominika Średnicka-Tober (a1) (a2), Marcin Barański (a1), Chris J. Seal (a3), Roy Sanderson (a4), Charles Benbrook (a5), Håvard Steinshamn (a6), Joanna Gromadzka-Ostrowska (a7), Ewa Rembiałkowska (a2), Krystyna Skwarło-Sońta (a8), Mick Eyre (a1), Giulio Cozzi (a9), Mette Krogh Larsen (a10), Teresa Jordon (a1), Urs Niggli (a11), Tomasz Sakowski (a12), Philip C. Calder (a13), Graham C. Burdge (a13), Smaragda Sotiraki (a14), Alexandros Stefanakis (a14), Sokratis Stergiadis (a1) (a15), Halil Yolcu (a1) (a16), Eleni Chatzidimitriou (a1), Gillian Butler (a1), Gavin Stewart (a1) and Carlo Leifert (a1)...


Demand for organic milk is partially driven by consumer perceptions that it is more nutritious. However, there is still considerable uncertainty over whether the use of organic production standards affects milk quality. Here we report results of meta-analyses based on 170 published studies comparing the nutrient content of organic and conventional bovine milk. There were no significant differences in total SFA and MUFA concentrations between organic and conventional milk. However, concentrations of total PUFA and n-3 PUFA were significantly higher in organic milk, by an estimated 7 (95 % CI −1, 15) % and 56 (95 % CI 38, 74) %, respectively. Concentrations of α-linolenic acid (ALA), very long-chain n-3 fatty acids (EPA+DPA+DHA) and conjugated linoleic acid were also significantly higher in organic milk, by an 69 (95 % CI 53, 84) %, 57 (95 % CI 27, 87) % and 41 (95 % CI 14, 68) %, respectively. As there were no significant differences in total n-6 PUFA and linoleic acid (LA) concentrations, the n-6:n-3 and LA:ALA ratios were lower in organic milk, by an estimated 71 (95 % CI −122, −20) % and 93 (95 % CI −116, −70) %. It is concluded that organic bovine milk has a more desirable fatty acid composition than conventional milk. Meta-analyses also showed that organic milk has significantly higher α-tocopherol and Fe, but lower I and Se concentrations. Redundancy analysis of data from a large cross-European milk quality survey indicates that the higher grazing/conserved forage intakes in organic systems were the main reason for milk composition differences.

  • View HTML
    • Send article to Kindle

      To send this article to your Kindle, first ensure is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about sending to your Kindle. Find out more about sending to your Kindle.

      Note you can select to send to either the or variations. ‘’ emails are free but can only be sent to your device when it is connected to wi-fi. ‘’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

      Find out more about the Kindle Personal Document Service.

      Higher PUFA and n-3 PUFA, conjugated linoleic acid, α-tocopherol and iron, but lower iodine and selenium concentrations in organic milk: a systematic literature review and meta- and redundancy analyses
      Available formats

      Send article to Dropbox

      To send this article to your Dropbox account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Dropbox.

      Higher PUFA and n-3 PUFA, conjugated linoleic acid, α-tocopherol and iron, but lower iodine and selenium concentrations in organic milk: a systematic literature review and meta- and redundancy analyses
      Available formats

      Send article to Google Drive

      To send this article to your Google Drive account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Google Drive.

      Higher PUFA and n-3 PUFA, conjugated linoleic acid, α-tocopherol and iron, but lower iodine and selenium concentrations in organic milk: a systematic literature review and meta- and redundancy analyses
      Available formats


This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (, which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited.

Corresponding author

* Corresponding author: Professor C. Leifert, fax +44 1661 831 006, email


Hide All
1. Willer, H & Kilcher, L (2011) The World of Organic Agriculture. Statistics and Emerging Trends 2011. FiBL-IFOAM Report. Bonn and Frick: IFOAM and FiBL.
2. Schultz, M & Huntrods, D (2011) Organic dairy profile. (accessed January 2013).
3. Soil Association (2011) Organic market report 2011. (accessed January 2013).
4. Yiridoe, EK, Bonti-Ankomah, S & Martin, RC (2005) Comparison of consumer perceptions and preference toward organic versus conventionally produced foods: a review and update of the literature. Renew Agric Food Syst 20, 193205.
5. Oughton, E & Ritson, C (2007) Food consumers and organic agriculture. In Handbook of Organic Food Quality and Safety, pp. 7494 [J Cooper, U Niggli and C Leifert, editors]. Cambridge: Woodhouse Publishing Ltd.
6. Mallatou, H, Pappas, CP, Kondyli, E, et al. (1997) Pesticide residues in milk and cheeses from Greece. Sci Total Environ 196, 111117.
7. Salas, JH, González, MM, Noa, M, et al. (2003) Organophosphorus pesticide residues in Mexican commercial pasteurized milk. J Agric Food Chem 51, 44684471.
8. Melgar, MJ, Santaeufemia, M & García, MA (2010) Organophosphorus pesticide residues in raw milk and infant formulas from Spanish northwest. J Environ Sci Health B 45, 595600.
9. European Food Safety Authority (2013) European Union report on pesticide residues in food. EFSA J 11, 3130.
10. Dangour, AD, Dodhia, SK, Hayter, A, et al. (2009) Nutritional quality of organic foods: a systematic review. Am J Clin Nutr 90, 680685.
11. 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, 177197.
12. Cooper, J, Niggli, U & Leifert, C (2007) Handbook of Organic Food Safety and Quality. Cambridge: CRC Press.
13. Palupi, E, Jayanegara, A, Ploeger, A, et al. (2012) Comparison of nutritional quality between conventional and organic dairy products: a meta-analysis. J Sci Food Agric 92, 27742781.
14. 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, 348366.
15. Hu, FB, Manson, JE & Willett, WC (2001) Types of dietary fat and risk of coronary heart disease: a critical review. J Am Coll Nutr 20, 519.
16. Parodi, PW (2009) Has the association between saturated fatty acids, serum cholesterol and coronary heart disease been over emphasized? Int Dairy J 19, 345361.
17. German, JB, Gibson, RA, Krauss, RM, et al. (2009) A reappraisal of the impact of dairy foods and milk fat on cardiovascular disease risk. Eur J Nutr 48, 191203.
18. Kliem, KE & Givens, DI (2011) Dairy products in the food chain: their impact on health. Annu Rev Food Sci Technol 2, 2136.
19. Sun, Q, Ma, J, Campos, H, et al. (2007) Plasma and erythrocyte biomarkers of dairy fat intake and risk of ischemic heart disease. Am J Clin Nutr 86, 929937.
20. Ruxton, CHS, Reed, SC, Simpson, MJA, et al. (2007) The health benefits of omega-3 polyunsaturated fatty acids: a review of the evidence. J Hum Nutr Diet 20, 275285.
21. Belury, MA (2002) Dietary conjugated linoleic acid in health: physiological effects and mechanisms of action. Annu Rev Nutr 22, 505531.
22. Nagao, K & Yanagita, T (2005) Conjugated fatty acids in food and their health benefits. J Biosci Bioeng 100, 152157.
23. Benjamin, S, Prakasan, P, Sreedharan, S, et al. (2015) Pros and cons of CLA consumption: an insight from clinical evidences. Nutr Metab (Lond) 12, 4.
24. Yang, B, Chen, H, Stanton, C, et al. (2015) Review of the roles of conjugated linoleic acid in health and disease. J Funct Foods 15, 314325.
25. Bhattacharya, A, Banu, J, Rahman, M, et al. (2006) Biological effects of conjugated linoleic acids in health and disease. J Nutr Biochem 17, 789810.
26. Brandt, K, Średnicka-Tober, D, Barański, M, et al. (2013) Methods for comparing data across differently designed agronomic studies: examples of different meta-analysis methods used to compare relative composition of plant foods grown using organic or conventional production methods, and a protocol for a systematic review. J Agric Food Chem 61, 71737180.
27. Butler, G, Nielsen, JH, Larsen, MK, et al. (2011) The effects of dairy management and processing on quality characteristics of milk and dairy products. NJAS-Wagen J Life Sci 58, 97102.
28. Benbrook, CM, Butler, G, Latif, MA, et al. (2013) Organic production enhances milk nutritional quality by shifting fatty acid composition: a United States-wide, 18-month study. PLOS ONE 8, e82429.
29. Schwendel, BH, Wester, TJ, Morel, PCH, et al. (2015) Invited review: organic and conventionally produced milk – an evaluation of factors influencing milk composition. J Dairy Sci 98, 721746.
30. Butler, G, Nielsen, JH, Slots, T, et al. (2008) Fatty acid and fat-soluble antioxidant concentrations in milk from high- and low-input conventional and organic systems: seasonal variation. J Sci Food Agric 88, 14311441.
31. Butler, G, Collomb, M, Rehberger, B, et al. (2009) Conjugated linoleic acid isomer concentrations in milk from high- and low-input management dairy systems. J Sci Food Agric 89, 697705.
32. Slots, T, Butler, G, Leifert, C, et al. (2009) Potentials to differentiate milk composition by different feeding strategies. J Dairy Sci 92, 20572066.
33. Larsen, MK, Nielsen, JH, Butler, G, et al. (2010) Milk quality as affected by feeding regimens in a country with climatic variation. J Dairy Sci 93, 28632873.
34. Stergiadis, S, Leifert, C, Seal, C, et al. (2012) Effect of feeding intensity and milking system on nutritionally relevant milk components in dairy farming systems in the North East of England. J Agric Food Chem 60, 72707281.
35. Barański, M, Średnicka-Tober, D, Volakakis, N, et al. (2014) Higher antioxidant and lower cadmium concentrations and lower incidence of pesticide residues in organically grown crops: a systematic literature review and meta-analyses. Br J Nutr 112, 794811.
36. Stewart, G (2010) Meta-analysis in applied ecology. Biol Lett 6, 7881.
37. Koricheva, J & Gurevitch, J (2013) Place of meta-analysis among other methods of research synthesis. In Handbook of Meta-Analysis in Ecology and Evolution, pp. 313 [J Koricheva, J Gurevitch and K Mengersen, editors]. Princeton, NJ: Princeton University Press.
38. Viechtbauer, W (2010) Conducting meta-analyses in R with the metafor package. J Stat Softw 36, 148.
39. Hedges, LV & Olkin, I (1985) Statistical Methods for Meta-Analysis. San Diego, CA: Academic Press.
40. Sanchez-Meca, J & Marin-Martinez, F (2010) Meta-analysis. In International Encyclopedia of Education, 3rd ed. pp. 274282 [P Peterson, E Baker and B McGaw, editors]. Amsterdam: Elsevier.
41. Lipsey, MW & Wilson, DB (2001) Practical Meta-Analysis. Applied Social Research Methods Series. Thousand Oaks, CA: Sage Publications.
42. Hedges, LV, Gurevitch, J & Curtis, PS (1999) The meta-analysis of response ratios in experimental ecology. Ecology 80, 11501156.
43. Mengersen, K, Schmidt, C, Jennions, M, et al. (2013) Statistical models and approaches to inference. In Handbook of Meta-Analysis in Ecology and Evolution, pp. 89107 [J Koricheva, J Gurevitch and K Mengersen, editors]. Princeton, NJ: Princeton University Press.
44. Rothstein, HR (2005) Publication bias in meta-analysis. In Publication Bias in Meta-Analysis, pp. 17 [HR Rothstein, AJ Sutton and M Borenstein, editors]. Chichester: John Wiley & Sons, Ltd.
45. Gurevitch, J & Hedges, LV (1999) Statistical issues in ecological meta-analyses. Ecology 80, 11421149.
46. Manly, BFJ (2001) Randomization, Bootstrap and Monte Carlo Methods in Biology, 2nd ed. New York: Chapman and Hall.
47. Guyatt, GH, Oxman, AD, Vist, GE, et al. (2008) GRADE: an emerging consensus on rating quality of evidence and strength of recommendations. BMJ 336, 924926.
48. Glasser, F, Doreau, M, Ferlay, A, et al. (2007) Technical note: estimation of milk fatty acid yield from milk fat data. J Dairy Sci 90, 23022304.
49. European Food Safety Authority (2010) Scientific opinion on dietary reference values for fats, including saturated fatty acids, polyunsaturated fatty acids, monounsaturated fatty acids, trans fatty acids, and cholesterol. EFSA J 8, 1461.
50. Anderson, GH (1994) Dietary patterns vs. dietary recommendations: identifying the gaps for complex carbohydrate. Crit Rev Food Sci Nutr 34, 435440.
51. Akoh, CC (1995) Lipid-based fat substitutes. Crit Rev Food Sci Nutr 35, 405430.
52. CJFt, Braak & Smilauer, P (1998) CANOCO Reference Manual and User’s Guide to Canoco for Windows: Software for Canonical Community Ordination (Version 4) . Wageningen: Centre for Biometry.
53. Walker, GP, Dunshea, FR & Doyle, PT (2004) Effects of nutrition and management on the production and composition of milk fat and protein: a review. Aust J Agric Res 55, 10091028.
54. Dewhurst, RJ, Shingfield, KJ, Lee, MRF, et al. (2006) Increasing the concentrations of beneficial polyunsaturated fatty acids in milk produced by dairy cows in high-forage systems. Anim Feed Sci Technol 131, 168206.
55. Jensen, SK, Johannsen, AK & Hermansen, JE (1999) Quantitative secretion and maximal secretion capacity of retinol, beta-carotene and alpha-tocopherol into cows’ milk. J Dairy Res 66, 511522.
56. Coppa, M, Ferlay, A, Chassaing, C, et al. (2013) Prediction of bulk milk fatty acid composition based on farming practices collected through on-farm surveys. J Dairy Sci 96, 41974211.
57. Adler, SA, Jensen, SK, Govasmark, E, et al. (2013) Effect of short-term versus long-term grassland management and seasonal variation in organic and conventional dairy farming on the composition of bulk tank milk. J Dairy Sci 96, 57935810.
58. International Dairy Federation (2011) Proceedings of IDF International Symposium on Sheep, Goat and other Non-Cow Milk. 16–18 May 2011, Athens, Greece.
59. Flachowsky, G, Franke, K, Meyer, U, et al. (2014) Influencing factors on iodine content of cow milk. Eur J Nutr 53, 351365.
60. Enjalbert, F, Lebreton, P & Salat, O (2006) Effects of copper, zinc and selenium status on performance and health in commercial dairy and beef herds: retrospective study. J Anim Physiol Anim Nutr (Berl) 90, 459466.
61. Bath, SC, Button, S & Rayman, MP (2012) Iodine concentration of organic and conventional milk: implications for iodine intake. Br J Nutr 107, 935940.
62. Haug, A, Høstmark, AT & Harstad, OM (2007) Bovine milk in human nutrition – a review. Lipids Health Dis 6, 25.
63. European Food Safety Authority (2013) Scientific opinion on the safety and efficacy of iodine compounds (E2) as feed additives for all animal species: calcium iodate anhydrous, based on a dossier submitted by Calibre Europe SPRL/BVBA. EFSA J 11, 3100.
64. Bath, SC & Rayman, MP (2015) Food fact sheet: iodine. (accessed July 2015).
65. Lavu, RV, Du Laing, G, Van de Wiele, T, et al. (2012) Fertilizing soil with selenium fertilizers: impact on concentration, speciation, and bioaccessibility of selenium in leek (Allium ampeloprasum). J Agric Food Chem 60, 1093010935.
66. McDonald, P, Edwards, RA & Greenhalgh, JFD (2011) Animal Nutrition, 7th ed. Harlow: Pearson.
67. Soil Association (2015) Enhancing iodine and other trace element content of organic milk. (accessed July 2015).
68. Simopoulos, AP & Cleland, LG (2003) Omega-6/omega-3 essential fatty acid ratio: the scientific evidence. World Rev Nutr Diet 92, 1174.
69. Raatz, SK, Silverstein, JT, Jahns, L, et al. (2013) Issues of fish consumption for cardiovascular disease risk reduction. Nutrients 5, 10811097.
70. Brasky, TM, Till, C, White, E, et al. (2011) Serum phospholipid fatty acids and prostate cancer risk: results from the prostate cancer prevention trial. Am J Epidemiol 173, 14291439.
71. Brasky, TM, Darke, AK, Song, X, et al. (2013) Plasma phospholipid fatty acids and prostate cancer risk in the SELECT trial. J Natl Cancer Inst 105, 11321141.
72. Bergamo, P, Fedele, E, Iannibelli, L, et al. (2003) Fat-soluble vitamin contents and fatty acid composition in organic and conventional Italian dairy products. Food Chem 82, 625631.
73. Emken, EA, Adlof, RO & Gulley, RM (1994) Dietary linoleic acid influences desaturation and acylation of deuterium-labeled linoleic and linolenic acids in young adult males. Biochim Biophys Acta 4, 277288.
74. Burdge, GC & Calder, PC (2005) Conversion of alpha-linolenic acid to longer-chain polyunsaturated fatty acids in human adults. Reprod Nutr Dev 45, 581597.
75. Brenna, JT, Salem, N Jr, Sinclair, AJ, et al. (2009) alpha-Linolenic acid supplementation and conversion to n-3 long-chain polyunsaturated fatty acids in humans. Prostaglandins Leukot Essent Fatty Acids 80, 8591.
76. Calder, PC, Kremmyda, LS, Vlachava, M, et al. (2010) Is there a role for fatty acids in early life programming of the immune system? Proc Nutr Soc 69, 373380.
77. van den Elsen, LWJ, van Esch, BCAM, Hofman, GA, et al. (2013) Dietary long chain n-3 polyunsaturated fatty acids prevent allergic sensitization to cow’s milk protein in mice. Clin Exp Allergy 43, 798810.
78. Childs, CE, Romeu-Nadal, M, Burdge, GC, et al. (2008) Gender differences in the n-3 fatty acid content of tissues. Proc Nutr Soc 67, 1927.
79. Williams, CM & Burdge, G (2006) Long-chain n-3 PUFA: plant v. marine sources. Proc Nutr Soc 65, 4250.
80. Welch, AA, Shrestha, SS, Lentjes, MAH, et al. (2010) Dietary intake and status of n-3 polyunsaturated fatty acids in a population of fish-eating and non-fish-eating meat-eaters, vegetarians, and vegans and the precursor-product ratio of alpha-linolenic acid to long-chain n-3 polyunsaturated fatty acids results from the EPIC-Norfolk cohort. Am J Clin Nutr 92, 10401051.
81. Massiera, F, Barbry, P, Guesnet, P, et al. (2010) A Western-like fat diet is sufficient to induce a gradual enhancement in fat mass over generations. J Lipid Res 51, 23522361.
82. Wijendran, V & Hayes, KC (2004) Dietary n-6 and n-3 fatty acid balance and cardiovascular health. Annu Rev Nutr 24, 597615.
83. Simopoulos, AP (2002) The importance of the ratio of omega-6/omega-3 essential fatty acids. Biomed Pharmacother 56, 365379.
84. Ryan, AS, Astwood, JD, Gautier, S, et al. (2010) Effects of long-chain polyunsaturated fatty acid supplementation on neurodevelopment in childhood: a review of human studies. Prostaglandins Leukot Essent Fatty Acids 82, 305314.
85. Kummeling, I, Thijs, C, Huber, M, et al. (2008) Consumption of organic foods and risk of atopic disease during the first 2 years of life in the Netherlands. Br J Nutr 99, 598605.
86. Christensen, JS, Asklund, C, Skakkebæk, NE, et al. (2013) Association between organic dietary choice during pregnancy and hypospadias in offspring: a study of mothers of 306 boys operated on for hypospadias. J Urol 189, 10771082.
87. Brantsæter, AL, Torjusen, H, Meltzer, HM, et al. (2015) Organic food consumption during pregnancy and hypospadias and cryptorchidism at birth: the Norwegian Mother and Child Cohort Study (MoBa). Environ Health Perspect (Epublication ahead of print version 9 July 2015).
88. Lawson, RE, Moss, AR & Givens, DI (2001) The role of dairy products in supplying conjugated linoleic acid to man’s diet: a review. Nutr Res Rev 14, 153172.
89. Whigham, LD, Watras, AC & Schoeller, DA (2007) Efficacy of conjugated linoleic acid for reducing fat mass: a meta-analysis in humans. Am J Clin Nutr 85, 12031211.
90. Willcox, JK, Ash, SL & Catignani, GL (2004) Antioxidants and prevention of chronic disease. Crit Rev Food Sci Nutr 44, 275295.
91. British Nutrition Foundation (2012) Nutrient requirements. (accessed July 2015).
92. Vanderpump, MPJ, Lazarus, JH, Smyth, PP, et al. (2011) Iodine status of UK schoolgirls: a cross-sectional survey. Lancet 377, 20072012.
93. Haug, A, Taugbøl, O, Prestløkken, E, et al. (2012) Iodine concentration in Norwegian milk has declined in the last decade. Acta Agric. Scand A Anim Sci 62, 127134.
94. European Food Safety Authority (2006) Tolerable upper intake levels for vitamins and minerals. (accessed April 2013).
95. Vinceti, M, Wei, ET, Malagoli, C, et al. (2001) Adverse health effects of selenium in humans. Rev Environ Health 16, 233251.
96. Phillips, DIW, Nelson, M, Barker, DJP, et al. (1988) Iodine in milk and the incidence of thyrotoxicosis in England. Clin Endocrinol (Oxf) 28, 6166.
97. Food and Agriculture Organization (2014) FAOstat. (accessed June 2015).
98. Zimmermann, MB (2009) Iodine deficiency. Endocr Rev 30, 376408.
99. Zimmermann, MB, Aeberli, I, Torresani, T, et al. (2005) Increasing the iodine concentration in the Swiss iodized salt program markedly improved iodine status in pregnant women and children: a 5-y prospective national study. Am J Clin Nutr 82, 388392.
100. Lim, KHC, Riddell, LJ, Nowson, CA, et al. (2013) Iron and zinc nutrition in the economically-developed world: a review. Nutrients 5, 31843211.
Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

British Journal of Nutrition
  • ISSN: 0007-1145
  • EISSN: 1475-2662
  • URL: /core/journals/british-journal-of-nutrition
Please enter your name
Please enter a valid email address
Who would you like to send this to? *


Type Description Title
Supplementary materials

Średnicka-Tober supplementary material

 Word (95 KB)
95 KB
Supplementary materials

Średnicka-Tober supplementary material
Średnicka-Tober supplementary material 1

 Word (2.0 MB)
2.0 MB


Altmetric attention score

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed