Use of peanut oil in eczema creams had OR 8 for peanut allergy but retrospective.
Filaggrin deficiency has OR 5 for food allergy, only 3 for eczema!
So could skin protection before early weaning prevent food allergy? Preliminary studies suggest 35- 50% response.
Jewish children in the UK have a prevalence of peanut allergy that is 10-fold higher than that of Jewish children in Israel. This difference is not accounted for by differences in atopy, social class, genetic background, or peanut allergenicity. Israeli infants consume peanut in high quantities in the first year of life, Bamba (peanut snack, like a Wotsit) often used for weaning, so most infants have been exposed by age 12 months. [Du Toit J Allergy Clin Immunol. 2008 Nov;122(5):984-9]
Gideon Lack at Evangelina hospital in London did LEAP study (Learning about Peanut Allergy), randomized infants with severe eczema and/or egg allergy to receive either no peanut until age 3yr, else an age-appropriate peanut snack (Bamba or smooth peanut butter, 6g) three times a week. Among the 530 infants in the intention-to-treat population who initially had negative results on the skin-prick test, the prevalence of peanut allergy at 60 months of age was 13.7% in the avoidance group and 1.9% in the consumption group (86% reduction, P<0.001). 98 participants had baseline positive SPT results, only 12% had a positive challenge so most continued the protocol. Another 10% with SPT>4mm were excluded from the start.
Adherence to the diet was excellent. Dust samples were taken from some participants’ beds, peanut levels were significantly higher for kids in consumption group. There was a higher rate of urticaria in the consumption group.
IgE greater than 10 in peanut avoiding group had 100% PPV for allergy. Peanut-specific IgG4 antibody seems to be linked to tolerance – it went up more in the consumption group, and IgG4:IgE ratio was generally lower in allergic group (most had IgG4 under 1000). [NEJM 2015; DOI: 10.1056/NEJMoa1414850] See also LEAP-On study, which is the follow up at 72 months, still significant difference.
Michael Perkins’ EAT study of early introduction of 6 common allergens in non-high risk babies showed if strict adherence to protocol eg 2g weekly of peanut, then every case of peanut allergy could be prevented.