BACKGROUND: There is uncertainty about the influence of diet during pregnancy and infancy on a child's immune development. We assessed whether variations in maternal or infant diet can influence risk of allergic or autoimmune disease.
METHODS AND FINDINGS: Two authors selected studies, extracted data, and assessed risk of bias. Grading of Recommendations Assessment, Development and Evaluation (GRADE) was used to assess certainty of findings. We searched Medical Literature Analysis and Retrieval System Online (MEDLINE), Excerpta Medica dataBASE (EMBASE), Web of Science, Central Register of Controlled Trials (CENTRAL), and Literatura Latino Americana em Ciências da Saúde (LILACS) between January 1946 and July 2013 for observational studies and until December 2017 for intervention studies that evaluated the relationship between diet during pregnancy, lactation, or the first year of life and future risk of allergic or autoimmune disease. We identified 260 original studies (964,143 participants) of milk feeding, including 1 intervention trial of breastfeeding promotion, and 173 original studies (542,672 participants) of other maternal or infant dietary exposures, including 80 trials of maternal (n = 26), infant (n = 32), or combined (n = 22) interventions. Risk of bias was high in 125 (48%) milk feeding studies and 44 (25%) studies of other dietary exposures. Evidence from 19 intervention trials suggests that oral supplementation with nonpathogenic micro-organisms (probiotics) during late pregnancy and lactation may reduce risk of eczema (Risk Ratio [RR] 0.78; 95% CI 0.68-0.90; I2 = 61%; Absolute Risk Reduction 44 cases per 1,000; 95% CI 20-64), and 6 trials suggest that fish oil supplementation during pregnancy and lactation may reduce risk of allergic sensitisation to egg (RR 0.69, 95% CI 0.53-0.90; I2 = 15%; Absolute Risk Reduction 31 cases per 1,000; 95% CI 10-47). GRADE certainty of these findings was moderate. We found weaker support for the hypotheses that breastfeeding promotion reduces risk of eczema during infancy (1 intervention trial), that longer exclusive breastfeeding is associated with reduced type 1 diabetes mellitus (28 observational studies), and that probiotics reduce risk of allergic sensitisation to cow's milk (9 intervention trials), where GRADE certainty of findings was low. We did not find that other dietary exposures-including prebiotic supplements, maternal allergenic food avoidance, and vitamin, mineral, fruit, and vegetable intake-influence risk of allergic or autoimmune disease. For many dietary exposures, data were inconclusive or inconsistent, such that we were unable to exclude the possibility of important beneficial or harmful effects. In this comprehensive systematic review, we were not able to include more recent observational studies or verify data via direct contact with authors, and we did not evaluate measures of food diversity during infancy.
CONCLUSIONS: Our findings support a relationship between maternal diet and risk of immune-mediated diseases in the child. Maternal probiotic and fish oil supplementation may reduce risk of eczema and allergic sensitisation to food, respectively.
AIM: To systematically review the association between breastfeeding and childhood allergic disease.
METHODS: Pre-determined inclusion/exclusion criteria identified 89 articles from PUBMED, CINAHL and EMBASE databases. Meta-analyses performed for categories of breastfeeding and allergic outcomes. Meta-regression explored heterogeneity.
RESULTS: More versus less breastfeeding (duration) was associated with reduced risk of asthma for children (5-18yrs), particularly in medium/low income countries, and with reduced risk of allergic rhinitis ≤5 years, but this estimate had high heterogeneity and low quality. Exclusive breastfeeding for 3-4 months was associated with reduced risk of eczema ≤2 years (estimate principally from cross-sectional studies of low methodological quality). No association found between breastfeeding and food allergy (estimate had high heterogeneity and low quality). Meta-regression found differences between study outcomes may be attributable to length of breastfeeding recall, study design, country income and date of study inception. Some of the protective effect of breastfeeding for asthma may be related to recall bias in studies of lesser methodological quality.
CONCLUSION: There is some evidence that breastfeeding is protective for asthma (5-18yrs). There is weaker evidence for a protective effect for eczema ≤2 years and allergic rhinitis ≤5 years of age, with greater protection for asthma and eczema in low income countries. This article is protected by copyright. All rights reserved.
BACKGROUND: The so-called 'hygiene hypothesis' postulates an inverse relationship between atopic dermatitis (AD) and an environment that leads to increased pathogen exposure.
OBJECTIVES: We sought to systematically identify, summarize and critically appraise: (i) the epidemiological evidence to suggest that environmental exposures that lead to an increase in microbial burden reduce the risk of AD; (ii) whether any specific infections have been shown to reduce AD risk; (iii) whether there is a link between immunizations, use of antibiotics and AD risk; and (iv) to comment on the new therapeutic approaches in AD that have evolved out of the 'hygiene hypothesis'.
METHODS: We searched Medline from 1966 until August 2004 to identify relevant studies for inclusion. Differences in study design and populations did not allow formal meta-analysis. Studies were therefore described qualitatively.
RESULTS: We identified 64 studies that were relevant to our review, 27 (42%) of which were of prospective design. There was prospective evidence to support an inverse relationship between AD and endotoxins, early day care and animal exposure. Two well-designed cohort studies have found a positive association between infections in early life and AD, and measles vaccination and AD. Antibiotic use was consistently associated with an increase in AD risk even into the antenatal period, although a few studies did not reach conventional statistical significance. A few small randomized controlled trials have suggested that probiotics can reduce AD severity and that probiotics may also be able to prevent AD to some degree.
CONCLUSIONS: Although population-based studies have suggested a consistent inverse relationship between AD and increasing family size, this does not seem to be explained by a straightforward increased exposure to a single environmental pathogen. The effect seen with early day care, endotoxin and animal exposure may be due to a nonpathogenic microbial stimulus of a chronic or recurrent nature. This would also explain the risk increase associated with antibiotic use. Caution should prevail in the prescribing of antibiotics early in life, especially in children with a family history of AD. Larger well-designed pragmatic trials on probiotics and the prevention and treatment of AD are now needed to inform whether such interventions should be used in routine clinical practice.
There is uncertainty about the influence of diet during pregnancy and infancy on a child's immune development. We assessed whether variations in maternal or infant diet can influence risk of allergic or autoimmune disease.
METHODS AND FINDINGS:
Two authors selected studies, extracted data, and assessed risk of bias. Grading of Recommendations Assessment, Development and Evaluation (GRADE) was used to assess certainty of findings. We searched Medical Literature Analysis and Retrieval System Online (MEDLINE), Excerpta Medica dataBASE (EMBASE), Web of Science, Central Register of Controlled Trials (CENTRAL), and Literatura Latino Americana em Ciências da Saúde (LILACS) between January 1946 and July 2013 for observational studies and until December 2017 for intervention studies that evaluated the relationship between diet during pregnancy, lactation, or the first year of life and future risk of allergic or autoimmune disease. We identified 260 original studies (964,143 participants) of milk feeding, including 1 intervention trial of breastfeeding promotion, and 173 original studies (542,672 participants) of other maternal or infant dietary exposures, including 80 trials of maternal (n = 26), infant (n = 32), or combined (n = 22) interventions. Risk of bias was high in 125 (48%) milk feeding studies and 44 (25%) studies of other dietary exposures. Evidence from 19 intervention trials suggests that oral supplementation with nonpathogenic micro-organisms (probiotics) during late pregnancy and lactation may reduce risk of eczema (Risk Ratio [RR] 0.78; 95% CI 0.68-0.90; I2 = 61%; Absolute Risk Reduction 44 cases per 1,000; 95% CI 20-64), and 6 trials suggest that fish oil supplementation during pregnancy and lactation may reduce risk of allergic sensitisation to egg (RR 0.69, 95% CI 0.53-0.90; I2 = 15%; Absolute Risk Reduction 31 cases per 1,000; 95% CI 10-47). GRADE certainty of these findings was moderate. We found weaker support for the hypotheses that breastfeeding promotion reduces risk of eczema during infancy (1 intervention trial), that longer exclusive breastfeeding is associated with reduced type 1 diabetes mellitus (28 observational studies), and that probiotics reduce risk of allergic sensitisation to cow's milk (9 intervention trials), where GRADE certainty of findings was low. We did not find that other dietary exposures-including prebiotic supplements, maternal allergenic food avoidance, and vitamin, mineral, fruit, and vegetable intake-influence risk of allergic or autoimmune disease. For many dietary exposures, data were inconclusive or inconsistent, such that we were unable to exclude the possibility of important beneficial or harmful effects. In this comprehensive systematic review, we were not able to include more recent observational studies or verify data via direct contact with authors, and we did not evaluate measures of food diversity during infancy.
CONCLUSIONS:
Our findings support a relationship between maternal diet and risk of immune-mediated diseases in the child. Maternal probiotic and fish oil supplementation may reduce risk of eczema and allergic sensitisation to food, respectively.
Systematic Review Question»Systematic review of interventions
