Ischaemic heart disease, Type 1 diabetes, and cow milk A1 beta-casein

AIM

To test the correlation of per capita A1 beta-casein (A1/capita) and milk protein with: 1) ischaemic heart disease (IHD) mortality; 2) Type 1 (insulin-dependent) diabetes mellitus (DM-1) incidence.

METHODS

A1/capita was estimated as the product of per capita cow milk and cream supply and its A1 beta-casein content (A1/beta) (calculated from herd tests and breed distribution, or from tests of commercial milk), then tested for correlation with: 1) IHD five years later in 1980, 1985, 1990 and 1995, in 20 countries which spent at least US $1000 (purchasing power parities) per capita in 1995 on healthcare; 2) DM-1 at age 0-14 years in 1990-4 (51 were surveyed by WHO DiaMond Project; 19 had A1 data). For comparison, we also correlated 77 food, and 110 nutritive supply FAO (Food and Agriculture Organization)-based measures, against IHD and DM-1.

RESULTS

For IHD, cow milk proteins (A1/capita, r = 0.76, p <0.001; A1/capita including cheese, r = 0.66; milk protein r = 0.60, p = 0.005) had stronger positive correlations with IHD five years later, than fat supply variables, such as the atherogenic index (r = 0.50), and myristic, the 14-carbon saturated fat (r = 0.48, p <0.05). The Hegsted scores for estimating serum cholesterol (r = 0.42); saturated fat (r = 0.37); and total dairy fat (r = 0.31) were not significant for IHD in 1995. Across the 20 countries, a 1% change in A1/capita in 1990 was associated with a 0.57% change in IHD in 1995. A1/capita correlations were stronger for male than female mortality. On multiple regression of A1/capita and other food supply variables in 1990, only A1/capita was significantly correlated with IHD in 1995. DM-1 was correlated with supply of: A1/capita in milk and cream (r = 0.92, p <0.00001); milk and cream protein excluding cheese (r = 0.68, p <0.0001); and with A1/beta in milk and cream (r = 0.47, p <0.05). Correlations were not significant for A2, B or C variants of milk beta-casein. DM-1 incidence at 0-4, 5-9 and 10-14 years was equally correlated (r = 0.80, 0.81, 0.81 respectively) with milk protein supply. A 1% change in A1/capita was associated with a 1.3% change in DM-1 in the same direction.

CONCLUSIONS

Cow A1 beta-casein per capita supply in milk and cream (A1/capita) was significantly and positively correlated with IHD in 20 affluent countries five years later over a 20-year period--providing an alternative hypothesis to explain the high IHD mortality rates in northern compared to southern Europe. For DM-1, this study confirms Elliott's 1999 correlation on 10 countries for A1/capita,1 but not for B beta-casein/capita. Surveys of A1 beta-casein consumption in two-year-old Nordic children, and some casein animal feeding experiments, confirm the A1/capita and milk protein/capita correlations. They raise the possibility that intensive dairy cattle breeding may have emphasised a genetic variant in milk with adverse effects in humans. Further animal research and clinical trials would be needed to compare disease risks of A1-free versus 'ordinary' milk.

Biochemical aspects in autism spectrum disorders: updating the opioid-excess theory and presenting new opportunities for biomedical intervention

Autism is a lifelong condition usually described as affecting social, cognitive and imaginative abilities. For many years, parents and some professionals have observed that in concordance with the behavioural and psychological symptoms of the condition, there are a number of physiological and biochemical correlates which may also be of relevance to the syndrome. One area of interest that encompasses many of these observations is the opioid-excess theory of autism. The main premise of this theory is that autism is the result of a metabolic disorder. Peptides with opioid activity derived from dietary sources, in particular foods that contain gluten and casein, pass through an abnormally permeable intestinal membrane and enter the central nervous system (CNS) to exert an effect on neurotransmission, as well as producing other physiologically-based symptoms. Numerous parents and professionals worldwide have found that removal of these exogenously derived compounds through exclusion diets can produce some amelioration in autistic and related behaviours. There is a surprisingly long history of research accompanying these ideas. The aim of this paper is to review the accompanying evidence in support of this theory and present new directions of intervention as a result of it.

Use of prick-tests in the screening of immediate allergy to protein: 16 cases

BACKGROUND

Allergy to protein hydrolysates seem to be on the rise but screening is difficult because of the wide range of symptoms. The goal of our study was to improve the screening process by skin prick testing infants with an anaphylactic form of allergy to cow's milk.

METHODS

We studied 92 infants who were allergic to cow's milk. The diagnosis was based on the results of skin prick tests, specific IgE assays, and oral food challenges. The skin prick tests were performed using a number of protein hydrolysate formulae and a synthetic amino acid-based formula available in France.

RESULTS

We detected sensitisation to the hydrolysates in 16 infants (17.3%), 15 by positive skin prick tests and one due to persistent symptoms on protein hydrolysate formulae (gastrointestinal manifestations, atopic dermatitis, and multiple food allergies), which completely receded when the synthetic amino acid formula was used as a substitute. Two infants had a positive hydrolysate oral food challenge test. There were no statistically significant differences in terms of age, sex, breastfeeding, clinical manifestations, family history, skin reaction size, or associated allergies. The infants who were sensitised to the hydrolysates had significantly higher specific IgE levels (whole milk,(_)-lactalbumin, and casein; median = 25.6 kU/L for cow's milk, p = 0.03) than those who were allergic to cow's milk but not sensitised to the hydrolysates.

CONCLUSIONS

Skin prick tests can be used to screen for sensitisation to hydrolysates in infants with IgE-mediated cow's milk allergy. They can also be used to determine the most suitable hydrolysate formula for individual infants.

Different beta-casein fractions in Icelandic versus Scandinavian cow's milk may influence diabetogenicity of cow's milk in infancy and explain low incidence of insulin-dependent diabetes mellitus in Iceland

OBJECTIVES

To compare children with insulin-dependent diabetes mellitus (IDDM) with controls in Iceland regarding their consumption of cow's milk in infancy, and to investigate the beta-casein fractions in Scandinavian and Icelandic cow's milk. The A1 variant of beta-casein has been shown to be diabetogenic in animal studies, and suggestions have been made that the B variant of beta-casein acts similarly. Differences in the relative proportions of beta-casein fractions might explain the lower incidence of IDDM in Iceland than in Scandinavia.

METHODS

A retrospective case-control study on IDDM patients and matching controls was performed in Iceland to compare their diets in infancy. Fifty-five children with IDDM born in Iceland over a 16-year period and randomly collected controls (n = 165) were recruited to the study. Mothers of the children answered questions on breastfeeding habits and on when cow's milk products were introduced. Samples of cow's milk from randomly selected milk batches from the largest consumption areas in Iceland and Scandinavia were collected. The milk samples were freeze-dried and their beta-casein fractions were analyzed using capillary electrophoresis.

RESULTS

No significant difference was found between IDDM patients and controls in the frequency and duration of breastfeeding or the first introduction of cow's milk products. The analyses of milk samples showed that the percentage of the A1 and B variants of beta-casein in Icelandic milk was significantly lower than in the milk from the Scandinavian countries.

CONCLUSIONS

Cow's milk consumption in infancy is not related to IDDM in Iceland. The lower fraction of A1 and B beta-caseins in Icelandic cow's milk may explain why there is a lower incidence of IDDM in Iceland than in Scandinavia.

Reversible hyperthyroidism and cardiomyopathy caused by consumption of iodocasein

We report the case of a 52-year-old woman with recent diagnosis of acute myocarditis and pericarditis, admitted for fever, tachycardia, and dyspnea upon exertion. Hematochemical parameters and instrumental examinations suggested iatrogenic hyperthyroidism and secondary dilated cardiomyopathy. Although gathering information about the medication used at home was initially difficult because of the patient's refusal to cooperate, she ended up by disclosing the regular assumption of an iodocasein drug. A complete and stable regression of the clinical picture was reached by suspending the iodine derivative and using cardiovascular drugs.

Anaphylaxis caused by the unexpected presence of casein in salmon

A new process for restructured meat and fish has been introduced to the market recently. Its main compound is casein, and it may therefore endanger patients with a milk allergy.

Development of immunoglobulin G and immunoglobulin E antibodies to cow's milk proteins and ovalbumin after a temporary neonatal exposure to hydrolyzed and whole cow's milk proteins

The ingestion of food antigens usually results in the induction of oral tolerance, but the clinical and immunologic consequences of brief exposure to cow's milk proteins during the neonatal period are not well-documented. The aim of this work was to study immunoglobulin (Ig)E and IgG responses to cow's milk proteins and ovalbumin after exposure during the first three days of life in infants who were otherwise exclusively breast-fed. A group of 129 infants was randomly assigned at birth to one of three feeding regimens: human milk (HM), cow's milk formula (CMF), or a casein hydrolysate formula (CHF), during the first three days of life. They were then all exclusively breast-fed for a varying period of time and followed for two years. Serum IgG and IgE antibodies to cow's milk proteins and ovalbumin (OVA) were analyzed in blood samples obtained at birth, at 4 days and at 2, 4, 8, 12 and 24 months of age. The levels of IgG antibodies to beta-lactoglobulin (IgG-BLG) and bovine serum albumin (IgG-BSA) were higher in the CMF and the HM groups than in the CHF group for up to two years. This was particularly obvious for IgG-BLG in infants who started weaning before two months. The levels of IgG antibodies to casein (IgG-CAS) were higher in the CMF group, as compared with the CHF group at 8 and 12 months. The levels of IgG antibodies to OVA were similar in all three feeding groups. The levels of IgE antibodies to CAS or OVA were similar in the three feeding groups. Exposure to cow's milk during the first three days of life stimulated IgG antibody production to cow's milk proteins and this was still obvious at 2 years of age, while feeding with a casein hydrolysate during the first three days of life was associated with low levels of IgG antibodies to cow's milk proteins.

Type I (insulin-dependent) diabetes mellitus and cow milk: casein variant consumption

Previously published Type I (insulin-dependent) diabetes mellitus incidence in 0 to 14-year-old children from 10 countries or areas was compared with the national annual cow milk protein consumption. Countries which were selected for study had appropriate milk protein polymorphism studies, herd breed composition information and low dairy imports from other countries. Total protein consumption did not correlate with diabetes incidence (r = +0.402), but consumption of the beta-casein A1 variant did (r = +0.726). Even more pronounced was the relation between beta-casein (A1+B) consumption and diabetes (r = +0.982). These latter two cow caseins yield a bioactive peptide beta-casomorphin-7 after in vitro digestion with intestinal enzymes whereas the common A2 variant or the corresponding human or goat caseins do not. beta-casomorphin-7 has opioid properties including immunosuppression, which could account for the specificity of the relation between the consumption of some but not all beta-casein variants and diabetes incidence.

Serum specific-IgE antibodies to peptides detected in a casein hydrolysate formula

Up to 2.5% of infants are affected by cow milk hypersensitivity in the first two years of life, although most of these children will "outgrow" their reactivity within 2-3 years. Extensively hydrolyzed ("hypoallergenic") cow milk-based formulae are often recommended as a substitute formula and are generally well tolerated. However, a small minority of cow milk-allergic children experience allergic reactions to the hypoallergenic formulae as well. Utilizing inhibition-ELISAs and sera from patients with IgE-mediated cow milk allergy, we have identified residual protein fractions less than 20 kD in several of the extensively hydrolyzed cow milk-based formulae. Although many of the cow milk allergic children had positive skin prick tests [SPT] to one of the hydrolysate formulae (Nutramigen), the positive skin test result generally did not correlate with clinical reactivity, although the negative predictive value of the negative SPT was excellent. Children with IgE-mediated cow milk allergy and a positive skin prick test to the hypoallergenic formula should probably receive their first dose of the formula in a medical setting so that appropriate therapy can be administered in the unlikely event of an allergic reaction.

Dietary cow's milk protein does not alter the frequency of diabetes in the BB rat

One theory of the pathogenesis of IDDM proposes that exposure to cow's milk proteins triggers the disease in genetically susceptible individuals. We tested this hypothesis in the BB/Wor rat model of human IDDM. Diabetes-prone (DP) BB/Wor rats spontaneously develop IDDM. Coisogenic diabetes-resistant (DR) BB/Wor rats do not develop diabetes spontaneously, but IDDM can readily be induced by treatment with polyinosinic:polycytidylic acid and depletion of RT6+ T-cells. Pregnant BB/Wor rats were fed one of four experimental diets or a standard Purina commercial rat chow (5010) that was certified to be free of cow's milk protein. Offspring were maintained on the maternal diet after weaning. DP-BB/Wor rats, fed either of two experimental diets based on hydrolyzed casein and free of intact milk protein (Nutramigen or D11236), developed diabetes at only half the rate of animals fed Purina 5010 chow. Neither the addition of bovine serum albumin (BSA) to Nutramigen nor the substitution of total milk protein for the hydrolyzed casein in the D11236 diet increased the frequency of spontaneous diabetes. In contrast, there was no relationship between diet and susceptibility of DR-BB/Wor rats to IDDM induction. However, the methods used to induce IDDM in DR-BB/Wor animals were found to induce antibodies against BSA. We conclude the following: 1) Dietary modification can reduce spontaneous IDDM expression in DP-BB/Wor rats, but the agent of protection is not elimination of cow's milk protein. 2) The addition of BSA or intact milk protein does not abrogate the effectiveness of a protective diet. 3) The genetic susceptibility of the DR-BB/Wor rat to autoimmune diabetes is unaffected by any of the tested diets, but a role of anti-BSA-like autoreactivity in IDDM expression cannot be excluded.

Rapid expression of the CD69 antigen on T cells and natural killer cells upon antigenic stimulation of peripheral blood mononuclear cell suspensions

The CD69 antigen has been identified as the earliest activation marker on the surface of cytokine- or mitogen-activated lymphocytes. The expression of this molecule may be a useful early marker of antigen- or allergen-specific activation of lymphocytes in vitro. We evaluated the expression of the CD69 and CD25 antigens on antigen- or allergen-stimulated lymphocytes and the proliferative responses as detected by thymidine incorporation. Peripheral blood mononuclear cells (PBMC) of allergic patients sensitized to Dermatophagoides pteronyssinus, bovine casein, or nickel sulfate were cultured in the absence or presence of clinically relevant allergens, tetanus toxoid, or recombinant interleukin (IL)-2. The respective binding of CD69 or CD25 antibodies to PBMC and thymidine incorporation were measured. An early expression of CD69, but not of CD25, antigen was detectable after 24-72 h of stimulation on up to 80% of natural killer (NK) cells and up to 10% of CD4+ T cells in PBMC cultures. Anti-IL-2 antibodies inhibited these increases of CD69 on NK cells and T cells by up to 60%. After 6 days of antigenic stimulation, the rates of both CD25+ and CD69+ lymphocytes were higher. Seventy-four percent of the CD25+ PBMC but only 55% of the CD69+ cells were CD3+ T lymphocytes at this time. No qualitative differences were detectable in allergen- or tetanus-toxoid-stimulated PBMC from allergic patients. The high expression of CD69 on NK cells in antigen-stimulated cultures suggests that these cells are easily activated by cytokines from antigen-stimulated T cells. CD69+ NK cells may serve as early-indicator cells in cultures with antigen- or allergen-stimulated mononuclear cells.

Non-promoting effects of iron from beef in the rat colon carcinogenesis model

Significant alarm has existed among the general public in the past few years that eating red meat may cause human colon cancer. Iron in beef has been hypothesized as one of the factors in the etiology of this cancer. The present study was designed to test the hypothesis that dietary iron solely from beef would enhance colon tumorigenesis induced in rats. Tumors were induced in Sprague-Dawley rats with 1,2-dimethylhydrazine (20 mg/kg body weight for 10 weeks). Seventy male weanling rats were randomized to two dietary treatment groups with two iron sources (very lean beef vs. iron citrate) as the factor. The rats were allowed free access to the respective diet and deionized water for 27 weeks. At termination of the study, the rats were examined for location, size and type of colon or extracolonic lesions. No significant differences were found in total incidence and number of colon tumors between the beef (51.7%, 0.8 tumors/rat) and casein (62.1%, 0.9 tumors/rat) diets, although the serum iron levels of rats fed the beef diet were higher than for those fed the casein diet. The results demonstrate that, when lean beef is used as an iron source, the risk for colon carcinogenesis is not increased.

Milk-responsive atopic dermatitis is associated with a casein-specific lymphocyte response in adolescent and adult patients

BACKGROUND

Specific T-cell responses to food antigens have been described in children with atopic dermatitis (AD). However, a subgroup of adolescent and adult patients still experiences food-responsive AD.

OBJECTIVE

This study was designed to evaluate lymphocyte responses to bovine casein in adult patients with AD.

METHODS

The stimulatory capacity of lipopolysaccharide-depleted bovine casein was tested in proliferation assays and in limiting dilution assays. Casein-specific T-cell clones (TCCs) were generated and characterized.

RESULTS

Higher proliferative responses to casein and modulation of cytokine receptors were observed in patients with milk-responsive AD compared with individuals without clinical reactions on milk ingestion. The results did not correlate with the amount of casein-specific IgE in the serum. The frequencies of T cells that grew in the presence of casein or house dust mite antigens were similar. Only 27% of CD4+ casein-specific TCCs from these patients, but the majority of house dust mite-specific TCCs, produced IL-4 on mitogen stimulation. Interferon-gamma, on the other hand, was produced by the majority of TCCs with both specificities.

CONCLUSION

A specific T-cell-mediated immune response to casein can be found in the blood of adolescent and adult patients with milk-related exacerbation of AD. In contrast to house dust mite-specific T cells, casein-specific T cells of adult patients who respond to cow's milk with worsening of AD produce little or no IL-4.

A lamb-meat-based formula for infants allergic to casein hydrolysate formulas

Ten infants with colitis due to milk protein allergy, presenting as hematochezia, whose symptoms did not resolve with the use of hydrolyzed cow-milk-based formulas, were treated with a modular lamb-meat-based formula (LOP). The patients were followed up for 3 months to 5 years. Prompt resolution of symptoms was achieved. In three patients, increased levels of creatinine and blood urea nitrogen and mild metabolic acidosis were noted, all returning to normal after the protein intake was lowered. All patients had normal growth. Seven patients were able to tolerate cow milk protein or soy at age 9-15 months. The LOP formula is well tolerated and is a safe alternative formula for infants allergic to cow milk hydrolysate formula.

Use of immunoblotting and monoclonal antibodies to evaluate the residual antigenic activity of milk protein hydrolysed formulae

BACKGROUND

Partial and extensive hydrolysed protein formulae have been developed to lower or eliminate the antigenicity of milk proteins. Although normally well tolerated, extensive hydrolysates have been reported to induce serious allergic reactions in very sensitive children. Moreover, clinical practice has often raised concern about the role of partial hydrolysates in cow's milk allergy prevention.

OBJECTIVE

Starting from these considerations, we used anti-casein monoclonal antibodies to evaluate the presence of residual antigenic activity in both partially and extensively protein hydrolysates.

METHODS

Electrophoretic analyses associated with immunoblotting technique were performed using nine protein-enriched commercial formulae.

RESULTS

The presence of different amounts of residual intact cow's milk proteins and/or polypeptidic material with conserved antigenic activity (according to the extensive or partial hydrolysis) was verified in most milk-based samples considered.

CONCLUSION

The use of monoclonal antibodies and immunoblotting could be useful for the quality of commercial 'hypoallergenic' formulae.