The microbiome, obesity and malnutrition Flashcards
What is obesity?
Abnormal or excess fat that has health implications and is characterised by a BMI over 30
Describe the study in mice lacking leptin
Mice who lacked the leptin hormone and thus had an obese phenotype, had a decrease in Bacteroidetes by 50% in a 16s RNA study
Describe the study in mice where metabolites were analysed
In a GC-MS study, there was an increase in fermentation products and short-chain fatty acids and also an increase in butyrate
Firmicutes are the key producers of butyrate in the gut
Describe the human study of different diets and their effects on the gut microbiota
12 obese people were randomly assigned either a fat or carbohydrate low-calorie diet then 16s RNA sequencing of that gut microbiota over the course of a year
At the phyla level, Firmicutes dominated at the start and then there was an increase in Bacteriodetes over the course of the diet
There was a correlation in weight loss and an increase in Bacteroidetes
What are the limitations of all of these studies?
Small cohorts studies
Other factors other than diet can influence the gut microbiota so it’s not that simple
What is wasting?
A low weight for height
What is stunting?
A low weight for age
What is underweight?
A low weight for age
Describe the study in Bangladesh
Those with moderate acute malnutrition or severe acute malnutrition have gut microbiota that is immature
Describe the study in Malawi
Microbiotas from healthy and undernourishes children were transplanted into germ-free mice
Mice transplanted with a healthy microbiota gained more weight and lean mass
Specific strains were identified that were different in mature and immature microbiota and those strains were transplanted into stunted mice
Those treated mice gained more weight and lean mass compared to the untreated control and a 16s RNA study showed differences in the microbiota between them
Describe the human breast milk study in Malawi
A mass spectrometry study of breast milk from Malawian mothers with healthy and severely stunted infants showed that the stunted breast milk had a decrease in the total sialylated and fucosylated milk oligosaccharides
Implanting faecal microbiota from the growth stunted child into germ-free mice resulted in growth deficiencies in the mice
Assing growth-promoting microbes or specific sialylated milk oligosaccharides helped
What is leptin?
A hormone that is responsible for calorific intake restriction
What are sialylated oligosaccharides?
Sugars with sialic acid (an alpha keto-acid sugar) added
What are fucosylated oligosaccharides?
Sugars that have a hexose deoxy sugar added
