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Gonzales-Malca JA, Tirado-Kulieva VA, Abanto-López MS, Aldana-Juárez WL, Palacios-Zapata CM. Worldwide research on the health effects of bovine milk containing A1 and A2 β-casein: Unraveling the current scenario and future trends through bibliometrics and text mining. Curr Res Food Sci 2023; 7:100602. [PMID: 37790856 PMCID: PMC10542606 DOI: 10.1016/j.crfs.2023.100602] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 09/19/2023] [Accepted: 09/22/2023] [Indexed: 10/05/2023] Open
Abstract
The possible adverse effect of consuming bovine milk with A1 β-casein (but not with A2 β-casein) on health aspects due to the release of β-casomorphin-7 (BCM-7) is currently under debate. The aim of this study was to perform a bibliometric analysis of studies extracted from Scopus to explore the relationship between BCM-7, A1 or A2 bovine milk with different aspects of health. Over time, several research groups were formed that are no longer active and although some authors have returned to the field of study, they have focused their efforts mainly on conducting reviews that show the same imprecise conclusions due to the few original articles. Research is concentrated in Europe and Asia, where New Zealand, China and Germany are the countries with the most publications, records and citations on the subject, respectively. On the other hand, no country in Africa or South America has scientific production, which opens the possibility of building collaborations between countries and exploring areas that lack scientific studies. Based on conflicting information from primarily in vitro and animal studies, and limited clinical trials with poor designs, A1 milk presents pro-inflammatory and oxidative activity, but the evidence is insufficient to associate its consumption with negative health effects. However, A2 milk may be better tolerated by the digestive system of some individuals, suggesting its possible modulating role in the intestinal microbiota. Stronger scientific evidence is needed to reach a consensus on whether the presence of β-casein A1 can significantly negatively affect health. The information shown will allow a better understanding of the subject and consumers will be able to make their own decisions regarding A1 or A2 milk.
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Affiliation(s)
- Jhony Alberto Gonzales-Malca
- Laboratorio de Tecnología de Alimentos y Procesos, Universidad Nacional de Frontera, Peru
- Laboratorio de Biología Molecular, Universidad Nacional de Frontera, Peru
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Acid and Rennet Coagulation Properties of A2 Milk. Foods 2022; 11:foods11223648. [PMID: 36429240 PMCID: PMC9689448 DOI: 10.3390/foods11223648] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 11/07/2022] [Accepted: 11/08/2022] [Indexed: 11/17/2022] Open
Abstract
This study investigated the acid and rennet milk coagulation properties of A2 milk (β-casein (CN) A2A2 genotype), in comparison to a control milk (blend of A2A1/A1A1/A2A2 genotypes). Acid and rennet coagulation were evaluated using the Optigraph® system, measuring the coagulation time, aggregation rate, and gel density or curd firmness. The acidification kinetics were monitored using a CINAC® system, evaluating the time to reach pH 4.6, the acidification rate, the maximum acidification rate, the time required to reach it, and the latency time. The water-holding capacity of acid milk gels and the potential yield, total solids, and syneresis of enzymatic gels were also evaluated. Some variables were highly influenced by the farm factor, showing the importance of the effect of extrinsic parameters. Acid and enzymatic coagulation times were not affected in either milk. The A2 milk presented higher acid gel density and latency time than the control milk. Although the differences in water-holding capacity were not statistically significant, the A2 milk presented lower values, related with the higher gel density. The A2 milk also showed higher rennet aggregation rate and curd firmness than the control milk. Potential yield and syneresis were higher in the A2 milk, which is in accordance with the higher firmness of curd. Coagulation results and gel and curd properties indicate that it is possible to manufacture acid and rennet coagulation dairy products from A2 milk with no major differences when compared with a control milk.
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Summer A, Di Frangia F, Ajmone Marsan P, De Noni I, Malacarne M. Occurrence, biological properties and potential effects on human health of β-casomorphin 7: Current knowledge and concerns. Crit Rev Food Sci Nutr 2020; 60:3705-3723. [PMID: 32033519 DOI: 10.1080/10408398.2019.1707157] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The genetic variant A1 of bovine β-casein (β-Cn) presents a His residue at a position 67 of the mature protein. This feature makes the Ile66-His67 bond more vulnerable to enzymatic cleavage, determining the release of the peptide β-Cn f(60-66), named β-casomorphin 7 (BCM7). BCM7 is an opioid-agonist for μ receptors, and it has been hypothesized to be involved in the development of different non-transmissible diseases in humans. In the last decade, studies have provided additional results on the potential health impact of β-Cn A1 and BCM7. These studies, here reviewed, highlighted a relation between the consumption of β-Cn A1 (and its derivative BCM7) and the increase of inflammatory response as well as discomfort at the gastrointestinal level. Conversely, the role of BCM7 and the effects of ingestion of β-Cn A1 on the onset or worsening of other non-transmissible diseases as caused or favored by still need proof of evidence. Overall, the reviewed literature demonstrates that the "β-Cn A1/BCM7 issue" remains an intriguing but not exhaustively explained topic in human nutrition. On this basis, policies in favor of breeding for β-Cn variants not releasing BCM7 and consumption of "A1-like" milk appear not yet sound for a healthier and safer nutrition.
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Affiliation(s)
- Andrea Summer
- Department of Veterinary Sciences, Università di Parma, Parma, Italy
| | | | - Paolo Ajmone Marsan
- Department of Animal Science, Food and Nutrition (DIANA) and Nutrigenomics and Proteomics Research Center (PRONUTRIGEN), Università Cattolica del Sacro Cuore, Piacenza, Italy
| | - Ivano De Noni
- Department of Food, Environmental and Nutritional Sciences (DeFENS), Università degli Studi di Milano, Milan, Italy
| | - Massimo Malacarne
- Department of Veterinary Sciences, Università di Parma, Parma, Italy
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De Groef B, Grommen SVH. An idea to explore: Genotyping bull sperm to introduce basic molecular biology techniques in an animal science course. BIOCHEMISTRY AND MOLECULAR BIOLOGY EDUCATION : A BIMONTHLY PUBLICATION OF THE INTERNATIONAL UNION OF BIOCHEMISTRY AND MOLECULAR BIOLOGY 2019; 47:708-711. [PMID: 31469506 DOI: 10.1002/bmb.21297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 07/20/2019] [Accepted: 08/13/2019] [Indexed: 06/10/2023]
Abstract
The laboratory exercise described here aims to provide a relevant context for learning basic DNA techniques in an introductory animal science course at tertiary level. In two 4-hr laboratory sessions, students assess the suitability of bulls for inclusion in a gene-assisted selection program for A2 β-casein by genotyping commercial bull sperm. Sperm cells are lysed to extract the genomic DNA, and PCR with primers for the β-casein gene is performed. Using the principle of amplification-created restriction sites, restriction digestion with TaqI can be used to distinguish between the A1 allele and the A2 allele of the gene. Cut PCR amplicons are separated by gel electrophoresis to evaluate the genotype of each bull. Students then write a diagnostic report with accompanying letter to their fictional client, explaining the DNA test, and interpreting the results. © 2019 International Union of Biochemistry and Molecular Biology, 47(6):708-711, 2019.
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Affiliation(s)
- Bert De Groef
- Department of Physiology, Anatomy and Microbiology, School of Life Sciences, La Trobe University, Bundoora, Victoria, 3086, Australia
| | - Sylvia V H Grommen
- Department of Physiology, Anatomy and Microbiology, School of Life Sciences, La Trobe University, Bundoora, Victoria, 3086, Australia
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Brooke-Taylor S, Dwyer K, Woodford K, Kost N. Systematic Review of the Gastrointestinal Effects of A1 Compared with A2 β-Casein. Adv Nutr 2017; 8:739-748. [PMID: 28916574 PMCID: PMC5593102 DOI: 10.3945/an.116.013953] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
This is the first systematic review, to our knowledge, of published studies investigating the gastrointestinal effects of A1-type bovine β-casein (A1) compared with A2-type bovine β-casein (A2). The review is relevant to nutrition practice given the increasing availability and promotion in a range of countries of dairy products free of A1 for both infant and adult nutrition. In vitro and in vivo studies (all species) were included. In vivo studies were limited to oral consumption. Inclusion criteria encompassed all English-language primary research studies, but not reviews, involving milk, fresh-milk products, β-casein, and β-casomorphins published through 12 April 2017. Studies involving cheese and fermented milk products were excluded. Only studies with a specific gastrointestinal focus were included. However, inclusion was not delimited by specific gastrointestinal outcome nor by a specific mechanism. Inclusion criteria were satisfied by 39 studies. In vivo consumption of A1 relative to A2 delays intestinal transit in rodents via an opioid-mediated mechanism. Rodent models also link consumption of A1 to the initiation of inflammatory response markers plus enhanced Toll-like receptor expression relative to both A2 and nonmilk controls. Although most rodent responses are confirmed as opioid-mediated, there is evidence that dipeptidyl peptidase 4 stimulation in the jejunum of rodents is via a nonopioid mechanism. In humans, there is evidence from a limited number of studies that A1 consumption is also associated with delayed intestinal transit (1 clinical study) and looser stool consistency (2 clinical studies). In addition, digestive discomfort is correlated with inflammatory markers in humans for A1 but not A2. Further research is required in humans to investigate the digestive function effects of A1 relative to A2 in different populations and dietary settings.
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Affiliation(s)
| | - Karen Dwyer
- School of Medicine, Faculty of Health, Deakin University, Geelong, Victoria, Australia
| | - Keith Woodford
- Agri-Food Systems, Lincoln University, Lincoln, New Zealand; and
| | - Natalya Kost
- Research Center of Mental Health, Russian Academy of Medical Sciences, Moscow, Russia
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Chia JSJ, McRae JL, Kukuljan S, Woodford K, Elliott RB, Swinburn B, Dwyer KM. A1 beta-casein milk protein and other environmental pre-disposing factors for type 1 diabetes. Nutr Diabetes 2017; 7:e274. [PMID: 28504710 PMCID: PMC5518798 DOI: 10.1038/nutd.2017.16] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Revised: 02/20/2017] [Accepted: 03/01/2017] [Indexed: 12/14/2022] Open
Abstract
Globally type 1 diabetes incidence is increasing. It is widely accepted that the pathophysiology of type 1 diabetes is influenced by environmental factors in people with specific human leukocyte antigen haplotypes. We propose that a complex interplay between dietary triggers, permissive gut factors and potentially other influencing factors underpins disease progression. We present evidence that A1 β-casein cows’ milk protein is a primary causal trigger of type 1 diabetes in individuals with genetic risk factors. Permissive gut factors (for example, aberrant mucosal immunity), intervene by impacting the gut’s environment and the mucosal barrier. Various influencing factors (for example, breastfeeding duration, exposure to other dietary triggers and vitamin D) modify the impact of triggers and permissive gut factors on disease. The power of the dominant trigger and permissive gut factors on disease is influenced by timing, magnitude and/or duration of exposure. Within this framework, removal of a dominant dietary trigger may profoundly affect type 1 diabetes incidence. We present epidemiological, animal-based, in vitro and theoretical evidence for A1 β-casein and its β-casomorphin-7 derivative as dominant causal triggers of type 1 diabetes. The effects of ordinary milk containing A1 and A2 β-casein and milk containing only the A2 β-casein warrant comparison in prospective trials.
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Affiliation(s)
- J S J Chia
- Immunology Research Centre, St Vincent's Hospital Melbourne, Fitzroy, Victoria, Australia
| | - J L McRae
- Immunology Research Centre, St Vincent's Hospital Melbourne, Fitzroy, Victoria, Australia
| | - S Kukuljan
- Freedom Foods Group Ltd, Sydney, New South Wales, Australia
| | - K Woodford
- Agricultural Management Group, Lincoln University, Christchurch, New Zealand
| | - R B Elliott
- Living Cell Technologies, Auckland, New Zealand
| | - B Swinburn
- School of Population Health, University of Auckland, Auckland, New Zealand
| | - K M Dwyer
- Immunology Research Centre, St Vincent's Hospital Melbourne, Fitzroy, Victoria, Australia.,School of Medicine, Faculty of Health, Deakin University, Geelong, Victoria, Australia.,Department of Medicine, The University of Melbourne, Melbourne, Australia
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Post-weaning effects of milk and milk components on the intestinal mucosa in inflammation. Mutat Res 2009; 690:64-70. [PMID: 20036674 DOI: 10.1016/j.mrfmmm.2009.12.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2009] [Revised: 12/14/2009] [Accepted: 12/15/2009] [Indexed: 12/16/2022]
Abstract
Many milk-derived components have immunomodulatory and anti-inflammatory properties, and some of these reduce intestinal inflammation when orally administered to animal models of colitis. However, the potential for ruminant milk or milk components to benefit people with intestinal inflammatory disorders (such as Inflammatory Bowel Disease) has not been well-researched. This review describes published research into mechanisms by which ruminant milk and its components may have beneficial effects when consumed by people who have intestinal inflammation.
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Merriman TR. Type 1 diabetes, the A1 milk hypothesis and vitamin D deficiency. Diabetes Res Clin Pract 2009; 83:149-56. [PMID: 19100644 DOI: 10.1016/j.diabres.2008.11.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2008] [Revised: 11/05/2008] [Accepted: 11/10/2008] [Indexed: 01/11/2023]
Abstract
The 'A1' genetic variant of beta-casein in milk has been linked to type 1 diabetes (T1D). The keystone piece of supporting evidence is an ecological study positively correlating the incidence of T1D with amount of A1 beta-casein consumption per capita. Of relevance, A1 beta-casein consumption is also positively correlated with latitude, itself implicated in T1D through vitamin D deficiency. Ecological and biological evidence convincingly implicate vitamin D deficiency in T1D. Latitude is a confounder of the ecological data that underpin the hypothesis that A1 beta-casein in cow's milk is a causative factor in T1D.
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Affiliation(s)
- Tony R Merriman
- Department of Biochemistry, University of Otago, PO Box 56, Dunedin, New Zealand.
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Schmelzer CEH, Schöps R, Reynell L, Ulbrich-Hofmann R, Neubert RHH, Raith K. Peptic digestion of β-casein. J Chromatogr A 2007; 1166:108-15. [PMID: 17720176 DOI: 10.1016/j.chroma.2007.08.015] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2007] [Revised: 08/01/2007] [Accepted: 08/02/2007] [Indexed: 11/21/2022]
Abstract
Numerous peptides obtained by enzymatic digestion of food proteins have been reported to exhibit biological activities. In this study, the focus was placed on peptides of beta-casein from bovine milk after a gastro-analogous in vitro digestion with pepsin, a protease with broad specificity. In order to study the time course of the digestion, the process was stopped after specific times and the samples were subjected to HPLC separation followed by matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) and nanoelectrospray (nanoESI) quadrupole time-of-flight (qTOF) mass spectrometry. A combined sequencing approach using de novo interpretation and databases was employed. Overall, 100% of the beta-casein sequence was covered by identifying 125 peptides of 4-84 residues in length, including 3 phosphorylated species. The results show that the peptic hydrolysis starts at the C-terminus of the protein. The release of known bioactive peptides from beta-casein following the peptic digestion under simulated gastric conditions is unlikely with a few exceptions. Furthermore, an amino acid variation was found, providing evidence for the existence of an additional genetic variant of beta-casein.
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Affiliation(s)
- Christian E H Schmelzer
- Institute of Pharmacy, Martin Luther University Halle-Wittenberg, Wolfgang-Langenbeck-Strasse 4, 06120 Halle (Saale), Germany
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Michalski MC. On the supposed influence of milk homogenization on the risk of CVD, diabetes and allergy. Br J Nutr 2007; 97:598-610. [PMID: 17349070 DOI: 10.1017/s0007114507657900] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Commercial milk is homogenized for the purpose of physical stability, thereby reducing fat droplet size and including caseins and some whey proteins at the droplet interface. This seems to result in a better digestibility than untreated milk. Various casein peptides and milk fat globule membrane (MFGM) proteins are reported to present either harmful (e.g. atherogenic) or beneficial bioactivity (e.g. hypotensive, anticarcinogenic and others). Homogenization might enhance either of these effects, but this remains controversial. The effect of homogenization has not been studied regarding the link between early cow's milk consumption and occurrence of type I diabetes in children prone to the disease and no link appears in the general population. Homogenization does not influence milk allergy and intolerance in allergic children and lactose-intolerant or milk-hypersensitive adults. The impact of homogenization, as well as heating and other treatments such as cheesemaking processes, on the health properties of milk and dairy products remains to be fully elucidated.
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Michalski MC, Januel C. Does homogenization affect the human health properties of cow's milk? Trends Food Sci Technol 2006. [DOI: 10.1016/j.tifs.2006.02.004] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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