Effects of prebiotics during pregnancy and lactation on infant allergies

Probiotics are live microorganisms promoted claimed to provide health benefits when consumed, generally by improving or restoring the gut microbiota. Prebiotics are compounds in food that foster growth or activity of beneficial microorganisms such as bacteria and fungi. Both are sold as dietary supplements, and there is hardly a human disease or symptom for which these supplements are not said to be effective.

One such claim is that the ingestion of prebiotics during pregnancy and lactation has immunomodulatory benefits for the developing fetal and infant immune system and provide a potential dietary strategy to reduce the risk of allergic diseases.

This study sought to determine whether maternal supplementation with dietary prebiotics reduces the risk of allergic outcomes in infants with hereditary risk.

A double-blind randomized controlled trial was conducted in which pregnant women were allocated to consume prebiotics (14.2 g daily of galacto-oligosaccharides and fructo-oligosaccharides in the ratio 9:1) or placebo (8.7 g daily of maltodextrin) powder. The treatment lasted from less than 21 weeks’ gestation until 6 months postnatal during lactation. All eligible women had infants with a first-degree relative with a history of medically diagnosed allergic disease. The primary outcome was medically diagnosed infant eczema by age 1 year, and secondary outcomes included allergen sensitization, food allergy, and recurrent wheeze by age 1 year.

A total of 652 women were randomized between June 2016 and November 2021 (329 in the prebiotics group and 323 in the placebo group). There was no significant difference between groups in the percentage of infants with medically diagnosed eczema by age 1 year (prebiotics 31.5% [103 of 327 infants] vs placebo 32.6% [105 of 322 infants]; adjusted relative risk, 0.98; 95% CI, 0.77-1.23; P = .84). Secondary outcomes and safety measures also did not significantly differ between groups.

The authors concluded that they found little evidence that maternal prebiotics supplementation during pregnancy and lactation reduces the risk of medically diagnosed infant eczema by age 1 year in infants who are at hereditary risk of allergic disease.

It is rare that we come across a well-planned, well-conducted and well-reported study of pro/prebiotics. When we do, it often casts doubts on the numerous claims made for these products.

Here we have such a study.

I congratulate the Australian authors for conducting it.