PhD defence - Lena Kirchner Brahe

Lena Kirchner Brahe is defending her PhD thesis

Obesity-related diseases

Dietary modulation of the gut microbiota

Time

4 juni 2014 at 13:00

Venue

Auditorium A2-70.04 Marmorhallen, Thorvaldsensvej 40, 1871 Frederiksberg C

Opponents

Associate Professor Stine Brandt Bering (Chair), Department of Nurtition, Exercise and Sports, Denmark.

Senior researcher Yolanda Sanz, the Spanish National Research Council, Institute of Agrochemistry and Food Technology, Spain.

Chief physician Jens M Bruun, Department of Medicine, Regional Hospital of Randers, Denmark.

Supervisors

Professor, MD head of Department Arne Astrup, Department of Nutrition, Exersice and Sports, Denmark.

Associate Professor Lesli Hingstrup Larsen, Department of Nutrition, Exersice and Sports, Denmark.

About the thesis

The prevalence of obesity has increased epidemically during the past four decades and worldwide more than half a billion adults are now obese. Obesity increases the risk of type 2 diabetes, cardiovascular diseases and cancer, which are among the leading causes of death worldwide. Thus, effective strategies to reduce morbidity and mortality caused by obesity are essential. Obesity is a consequence of an imbalance between energy intake and expenditure caused by a complex interplay between nutritional, physiological, social and environmental factors and the genetic susceptibility. Recently, it has been hypothesized that not only the human genome but also the genome of the microbes within the gut is implicated in the pathogenesis of obesity and that the gut microbes might constitute a target for prevention of obesity-related diseases. The primary aim of this PhD was to identify gut microbes associated with metabolic risk markers in obesity and to explore if food components that modulate the gut microbiota can improve health.

A clinical trial including 58 obese women was conducted to identify gut bacteria associated with markers for insulin resistance, lipid metabolism and inflammation, and to explore the effect on these metabolic markers following intake of the probiotic Lactobacillus paracasei F19 or flaxseed mucilage. The results showed that several gut bacteria are linked to metabolic risk markers in obesity, also after adjustment for potential confounders such as body composition and long-term diet composition. In addition, intake of flaxseed mucilage improved insulin sensitivity and altered the gut microbiota. However, the improved insulin sensitivity did not appear to be mediated by the changes in the gut microbiota composition.

In summary, the work presented in this PhD supports a link between the gut microbes and metabolic disturbances in obesity, but does not provide evidence to claim that diet-induced modulation of the gut microbiota can improve metabolic health.

2014, 120 pages, ISBN 978 87 7611 748 1