Abstracts

Substantial support is added to the evidence that children not breastfed have a greater risk of obesity in later life. German researchers in Bavaria, collected height and weight data and applied a questionnaire to parents to determine early feeding practices, diet and lifestyle of 9375 school children. Those, whose body mass were above the 97^th percentile for all German children were defined as obese. Exclusively breastfed were those who had received no food and drink other than breastmilk.

The prevalence of obesity was found to be 4.5 per cent in those who had never been breastfed compared to 2.8 per cent for those exclusively breastfed

Moreover, the duration of breastfeeding indicated a clear dose-response effect. The prevalence was 3.8 per cent for those breastfed for 2 months, 2.3 per cent for those exclusively breastfed for 3 to 5 months; 1.7 per cent for 6 to 12 months and 0.8 per cent for those breastfed for longer than 12 months. Similarly a dose-related response was observed for the prevalence of being overweight. Social class or lifestyle was not attributable to these differences.

The authors listed a number of "key messages" as follows:

• Obesity is the most frequent nutritional disorder in children, and is an important risk factor for cardiac disease in adulthood
• Preventing obesity in children should be a useful strategy in preventing later heart disease because weight loss intervention in obese children are costly and rarely successful
• Data from a cross sectional study in Bavaria suggests that the risk of obesity in children at the time of school entry can be reduced by breastfeeding: a 35 per cent reduction occurs if children are breastfed for 3 to 5 months
• Preventing obesity and its consequences may be an important argument in the drive to encourage breastfeeding in industrialized countries.

Observations linking early exposure to cow's milk formula proteins to the development of type 1 diabetes (juvenile-onset) have been reported in the scientific literature for some time. Researchers from Finland have now confirmed that early oral exposure to cow's milk protein induces an insulin immune response. In diabetes-prone children this can bring about autoimmune pancreatic beta cell destruction

Type 1 diabetes is known to be the result of the destruction of pancreatic beta-cells and the immunization to insulin plays a key role in the autoimmune destructive course leading to pancreatic cell loss.

This study compared 100 infants who were exposed to cow's milk formula before the age of 12 weeks and 100 infants who were exclusively breastfed for longer than their first 12 weeks.

They found that the amount of IgG-antibodies binding to bovine insulin higher was higher at 3 months for babies exposed to cow's milk formula than in infants who were exclusively breastfed. The antibodies binding to bovine insulin also reacted with human insulin.

From this the authors conclude that primary immunization to insulin is induced in infancy by oral exposure to cow's milk insulin, indicating sensitization to insulin in non-diabetic children. The possibility that insulin-specific lymphocytes induced by cow's milk feeding may be activated in some children needs to be considered as a possibly mechanism leading to autoimmune destruction of beta cells and subsequent progression to clinical type 1 diabetes.

Dr Akerblom's research was presented at the 59^th Annual Scientific Sessions of the American Diabetes Association in San Diego, June, 1999. Colleague Dr Hans-Michael Dosch from the Hospital for Sick Children, Toronto, commented that "evidence against cow's milk is piling up". He cited the example of Puerto Rico where fewer than 5 per cent of mothers breastfeed and the majority use cow's milk based formulas. Meanwhile type 1 diabetes is 10 times the rate as seen in Cuba where breastfeeding is nearly universal.