SYMBA – Promoting gut health (symbiosis) with prebiotic fibre for prevention of allergic disease

The SYMBA Study aims to examine if a high fibre prebiotic supplement, taken during pregnancy and whilst breastfeeding, will reduce the risk of allergic disease in children, with potential benefit to other aspects of health, growth and development. SYMBA is the first intervention study nested within the ORIGINS Project, a birth cohort aiming to recruit 10,000 families in the Joondalup area of Perth, Australia.

SYMBA is the first randomised controlled trial (RCT) to determine if modulating the maternal gut microbiome from early pregnancy will reduce the risk of infant allergic disease. Allergic diseases are the most common chronic diseases of childhood, and the earliest manifestation of the vulnerability of the immune system to modern environmental change.  Modern, refined low-fibre diets are a major determinant of changing gut microflora, and associated inflammation and disruptions in ‘gut homeostasis’ and immune maturation. Soluble ‘prebiotic’ fibre (oligosaccharides) are now recognized as key immune-modulating molecules, both through direct local and systemic anti-inflammatory effects and through favourable effects on gut colonization. With evidence the fetal immune system is highly active and responsive to the mother and her environment, it is logical to intervene much earlier, when these responses are developing.

AIM: To assess the ability of a maternal dietary intervention of high fibre/prebiotic supplement from second trimester of pregnancy to six months post-partum to reduce infant eczema and allergic sensitisation at 12 months of age, relative to the placebo group. To our knowledge this will be the first study to examine the clinical effects of prebiotics in human pregnancy and lactation on allergic disease.

HYPOTHESIS: There is mounting evidence that ‘refined’ low-fibre diets contribute to the differences in gut colonisation associated with the increase in allergic disease and other inflammatory disorders, and that these effects begin in utero. We hypothesise that:

H1.        Increasing maternal dietary fibre intake with prebiotic supplementation will reduce the risk of infant allergic disease.

H2.        The intervention will favourably influence maternal gut colonisation and increase short chain fatty acid (SCFA) metabolites, known to influence immune development in utero. It will also promote species richness during infant colonisation (e.g. abundance of Bacteroidacea).

H3.        This intervention will have immunomodulatory effects associated with markers of immune tolerance (at birth and in the postnatal period) as suggested in pilot studies.

DESIGN: Randomised controlled double-blind trial

Inclusion criteria: Families who are planning on delivering their baby at Joondalup Health Campus: pregnant women whose babies have an immediate family member (mother, father or sibling) with a history of one or more allergies (asthma, hayfever, eczema and/or food allergy).

EXCLUSION CRITERIA: Maternal smoking during pregnancy, maternal age <18 years, women >21 weeks gestation and women already consuming regular prebiotic supplements.

STUDY INTERVENTION: Participating women will take the study powder daily from 18-20 weeks gestation in pregnancy until 6 months of lactation.

Outcome Assessments: Primary Clinical Outcome: The primary clinical outcome will be medically diagnosed eczema in the infant at 12 months of age. Secondary Clinical Outcomes: We will also examine for other allergic disease manifestations during infancy and early childhood (up to 5 years of age).