Research News

How do bacteria affect the brain at different life stages?

Thursday, 27 October 2016 09:16

Growing evidence (at least from mouse models) suggests gut bacterial composition in early life can have effects on the brain; at the Harvard Symposium, Tracy Bale of University of Pennsylvania (USA) detailed her work showing that exposing mice to stress in early pregnancy changes their vaginal microbiome and induces similar-looking changes in the offspring’s gut microbiota at birth. These changes may alter the brain, for example, by reprogramming the young mouse’s hypothalamus, with various effects on behaviour. Bale also noted that the effects of early prenatal stress in mice are greater and more persistent in males, raising the question of whether there could be sex-specific interventions to offset these effects.

Later came the opposite end of the lifespan: in the example of Parkinson’s disease, gut microbiota may also exert effects. Filip Scheperjans of Helsinki University Hospital (Finland) presented a talk on Parkinson’s disease and the slowly growing number of studies that link it to gut microbiota compositional differences. He described three studies showing dysbiosis in Parkinson’s disease, but noted that the nature of the dysbiosis was different from study to study. Further research is required to find out whether probiotic interventions could improve motor symptoms themselves, or only the gastrointestinal symptoms (e.g. constipation) associated with the condition.

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What are humans’ earliest microbial exposures?

Thursday, 27 October 2016 09:12

Physicians and researchers have long thought babies in the womb were sterile and that their first microbial exposures occurred during birth. At the symposium, Kjersti Aagaard of Baylor College of Medicine (USA) walked the audience through the growing evidence that microbial exposure starts before birth. Aagaard says her lab, and now seven others, have found evidence of culturable bacteria in the placenta. She noted that the placenta constitutes a microbially sparse habitat compared with other body sites—its bacterial load lies somewhere between a hot tub and the New York subway.

Aagaard showed data suggesting the microbiome of neonatal meconium varies according to the mother’s diet during gestation—namely, her fat intake. This connection underscores the importance of maintaining an appropriate diet and a healthy microbial community during pregnancy.

Josef Neu of University of Florida (USA) continued the theme of early microbial exposure by talking about microbes in the guts of infants who are breastfed. Neu mentioned the advantages of breastmilk for the developing infant and noted that a baby’s microbial dose from human milk is similar to the dose used in some probiotics studies. He predicted that in the future, mothers who cannot breastfeed may have access to more advanced products that approximate breastmilk: potentially beneficial microbes could be added to pasteurized donor milk, for example.

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Exploring the clinical usefulness of the low-FODMAP diet for Crohn’s disease

Tuesday, 18 October 2016 11:26

A diet low in FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides and polyols) has been studied mostly in the context of irritable bowel syndrome (IBS) and is known to reduce functional gastrointestinal symptoms in this population. In addition, altering FODMAP intake appears to impact fecal microbiota composition in both healthy individuals and those with IBS.

The observed success of the low-FODMAP diet in reducing gastrointestinal (GI) symptoms in IBS made a group of researchers ask whether the diet could also address functional GI symptoms in those with inflammatory bowel diseases (IBDs) such as Crohn’s disease. This idea was explored in a recent study from the group at Monash University (Australia) that originally developed and tested the low-FODMAP diet.

In this cross-over trial, researchers first tracked the habitual diets of a small group of nine patients with inactive Crohn’s disease. Next, each participant was randomized to 21 days of a provided experimental diet: either (1) low-FODMAP or (2) typical “Australian”. After a washout period of his or her habitual diet for at least 21 days (until GI symptoms had returned to baseline), each participant consumed the other experimental diet for an additional 21 days.

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Dietary fibre/short-chain fatty acids and vitamin A may protect mice against peanut allergy via gut microbiota

Tuesday, 18 October 2016 11:18

The incidence of food allergies has increased dramatically in western countries over the past 20 years and the gut microbiota seems to be a promising target for preventing and treating them. However, mechanisms by which gut microbiota is involved in the loss of oral tolerance remain unclear.

A recent study, led by Dr. Charles Mackay from the Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology at Monash University in Clayton (Australia), has found that the development of food allergies in mice could be linked to dietary elements including fibre and vitamin A.

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