Despite numerous studies, there is no consistent evidence showing clear benefits of various nutritional factors on the risk of atopic dermatitis (AD) in children, according to a recent review.
Among the nutritional factors examined by the authors of a literature review in Frontiers in Pediatrics, vitamin D and oral probiotics and prebiotics appeared to most likely to protect against AD. However, they concluded that further study in both areas was necessary to be able to give any recommendations.
AD is a common inflammatory disease that affects up to one-fifth of individuals around the world and is associated with financial and psychosocial burden. Some evidence suggests AD is primarily a skin barrier defect and that it could be a causative factor in the development of food allergy and other atopic illness, including asthma and allergic rhinitis. Its prevalence has increased significantly in industrialized and developing countries in the last few decades.
The authors reviewed a series of factors regarding the mother’s diet during pregnancy, the infant’s diet, and breastfeeding to seek links between nutritional factors and developing AD. There was no consistent evidence linking nutritional factors to AD.
However, vitamin D, probiotics, and prebiotics appeared to hold the most promise, the authors indicated. In one Norwegian study, researchers randomly selected 30 children aged 4 to 13 years with severe AD to settle in a tropical zone for 4 weeks—where intake of vitamin D via sunlight would be increased—and 26 children to remain in Norway. Significant improvements were found in the children in the tropical zone.
A double-blind randomized control trial (RCT), in which 60 patients with AD aged 14 and older were randomly selected to receive 1600 IU/day of vitamin D or placebo, found significant improvement for the group taking the vitamin. Still, the authors said, there are conflicting data on vitamin D; further RCTs are needed to establish the optimal dose, desired levels, duration of treatment, and effect of vitamin D supplementation on the prevention and treatment of AD.
The theory behind probiotics and prebiotics having a link stems from activation of the interleukin 4 (IL-4)/IL-13 axis in AD promoting the skin barrier breakdown and its association with changes in gut microbiota. A recent double-blind RCT with 50 children of aged 4 to 17 years reported that a mixture of Bifidobacterium strains was effective in reducing AD severity. In a 2-year follow-up RCT that included 132 infants at risk of atopy, the authors found the cumulative incidence for AD was lower in the group fed with a formula containing a mixture of prebiotic oligosaccharides (13.6%) compared with the placebo group (27.9%).
The authors said specific probiotic strains may prove beneficial but must be further studied, noting that strain-specific effects of probiotics make it difficult to make recommendations.
Meanwhile, evidence on breastfeeding and allergy risk is conflicting, the authors said, even though international scientific studies recommend exclusive breastfeeding for 4 to 6 months to prevent allergic disease.
“[T]he effect of breastfeeding on the risk of AD remains controversial, possibly due to different study populations and designs, and requires more randomized controlled trials,” the authors wrote.
Conflicting evidence also was found regarding maternal diet during pregnancy, maternal vitamin D intake during pregnancy, hydrolyzed formula feeding, postnatal vitamin D intake, and omega-3 long-chain polyunsaturated fatty acids. Evidence indicated that the delayed introduction of solids did not reduce the risk of allergic sensitization and atopic diseases, the authors wrote.
“Long-term follow-up studies are essential to determine the true benefit of prenatal and early life dietary and nutritional interventions as a primary prevention strategy for AD,” they concluded.
Trikamjee T, Comberiati P, D'Auria E, Peroni D, Zuccotti GV. Nutritional factors in the prevention of atopic dermatitis in children. Front Pediatr. Published January 12, 2021. doi:10.3389/fped.2020.577413