Nuts in pregnancy

What pregnant women should or should not eat or drink to protect their children from developing allergy has proved highly controversial, with conflicting advice from different authorities, sometimes diametrically opposed. Paediatricians seeing allergic children are often asked about this by mothers. A longitudinal study from the US, the Growing Up Today Study 2, looked at outcomes in over 8000 children born from 1990 to 1994, with regard to ‘physician-diagnosed food allergy’ (Frazier and colleagues. JAMA Pediatr doi:10.1001/jamapediatrics.2013.4139). On all these they held contemporaneous data on the mothers’ diets during pregnancy. They found that, in the offspring of non-allergic mothers, the incidence of peanut and tree-nut allergy was significantly less in those whose mothers ate more nuts (nuts eaten >5 times vs.<1 time per month: OR 0.31; 95% CI 0.13–0.75). In the much smaller group of nut allergic mothers, the risk was increased, albeit not significantly. There are laboratory data suggesting a protective effect of consuming potential allergens during pregnancy, so should this study make us change the advice given: eat more nuts to protect your child? There are many possible confounding factors – does having ‘non-allergic’ genes encourage people to eat more nuts anyway? So cause and …