Setting the record straight: A1 beta-casein, heart disease and diabetes

• Published in: New Zealand medical journal Vol. 116; no. 1170; p. U375
• Main Authors: McLachlan, Corran, Olsson, Felix
• Format: Journal Article
• Language: English
• Published: New Zealand Pasifika Medical Association Group (PMAG) 14.03.2003
• Subjects: Adolescent; Adult; Aged; Animals; Cardiovascular disease; Caseins - adverse effects; Cattle; Child; Child, Preschool; Diabetes; Diabetes Mellitus, Type 1 - epidemiology; Diet; Humans; Incidence; Male; Middle Aged; Milk; Milk - adverse effects; Milk - chemistry; Myocardial Ischemia - mortality; Proteins
• ISSN: 1175-8716; 1175-8716

What struck McLachlan was the remarkable similarity between IDDM incidence rates and ischaemic heart disease (IHD) mortality data that he had encountered in work to commercialise a process to manufacture low-cholesterol or cholesterol-free foodstuffs.8 This observation is illustrated in the following plot of IDDM incidence in 0 to 14-year-old males9,10 versus population standardised heart disease mortality data for 30 to 69-year-old males11 (Figure 1). [...]it did not show a stronger relationship with A1 + B as reported later by Elliott and Hill for IDDM, and showed no significant relationship with any of the other major proteins in milk: β-lactoglobulins A and B; α-caseins A, B or C; β-caseins A1, A2, A3, B or C; or κ-casein A and B. In the meantime, Elliott and Hill, from a more detailed knowledge of the β-casein amino acid structures, proposed that one fragment of the A1 β-casein molecule, later refined to casomorphin-7, was their candidate molecule for IDDM damage.17 This theory required B β-casein to be as damaging as A. When McLachlan's findings were presented to the NZ Dairy Board, their milk scientists rejected the analyses on various grounds, including those that a number of sets of data were from PhD theses and had not been subject to peer review, and that the number of animals measured in some breeds were too small to allow accurate phenotype data to be calculated. [...]the NZ Dairy Research Institute report set out the following graph and concluded that the McLachlan data was not supported (Figure 2).18 [Figure omitted, see PDF] Figure 2.