A Norwegian study published in 2003 suggested that children given cod liver oil in infancy were less likely to develop type 1 diabetes. Now a study in Denver, Colorado (JAMA 2007;298:1420–8) has demonstrated a protective effect of early intake of omega-3 fatty acids against the development of islet autoimmunity in children at increased genetic risk of type 1 diabetes. Among 1770 children with either a first-degree family history of type 1 diabetes or a genotype associated with increased risk of type 1 diabetes, 58 developed islet autoimmunity during follow up to a mean age of 6.2 years. Dietary intake of omega-3 fatty acids was inversely related to risk of islet autoimmunity. In a case-cohort study of 244 children there was also an inverse relationship between omega-3 fatty acid content of erythrocyte membranes and risk of islet autoimmunity. A trial of supplementation with docosahexanoic acid in utero and infancy to prevent islet damage in high risk infants is in progress.

Two UK studies of thiomersal (thimerosol in the USA), which is 49.6% mercury by weight and metabolised to ethyl mercury, were published in 2004 and largely exonerated thiomersal-containing vaccines from causing neurodevelopmental harm. Now a third study, in the USA, (New England Journal of Medicine 2007;357:1281–92; see also Perspective, ibid:1278–9) has given …