Agarose, a polysaccharide polymer material — usually extracted from seaweed — is easily hydrolysed to produce oligosaccharides known as agaro-oligosaccharides (AGO).
They are said to be able to influence gut microbiota, which are "deeply associated with the prevalence of obesity".
As such, researchers conducted a study to determine the AGO’s effects on gut microbial composition and obese phenotype in mice.
Five-week-old male mice were used in the study. They were given free access to water and food for one week, before being divided into two groups of six.
One group was given AGO in drinking water for eight weeks; the researchers also obtained fresh stool samples from each mouse during a four-week feeding period.
Their faecal microbiota profiles were then assessed, and the researchers found that compared with the control group, the AGO mice had "significantly reduced epididymal adipose tissue weights and serum non-esterified fatty acid concentrations".
They also observed that concentrations of primary bile acids — synthesised in the liver from cholesterol by liver enzymes — had a tendency to increase in the AGO mice.
On the other hand, their concentrations of secondary bile acids — which "contribute to increased reactive oxygen species, DNA damage, genomic instability, and tumour growth" — did not increase.
In addition, they found that AGO administration was directly linked to greater abundance of certain types of gut bacteria in the mice, which was negatively associated with epididymal adipose tissue weight, but said "the reasons for the elevations of these genera remain unclear".
Positive outcome, but more proof needed
The researchers stated that while the definitive role of the AGO mice's gut microbes had not yet been discovered, their data showed how AGO might affect gut microbial composition and prevent obesity.
They further hypothesised that this suggested that AGO’s modulation of gut microbes might be a contributing factor in its anti-obesity properties.
They concluded: "To elucidate the definitive role of gut microbes of AGO-receiving mice, further investigations using faecal transplantation must be conducted. However, our data demonstrate the possibility that oral intake of AGO prevents obesity and its related disorders."
Source: The Journal of Nutritional Science and Vitaminology
"Agaro-Oligosaccharides Regulate Gut Microbiota and Adipose Tissue Accumulation in Mice"
Authors: Yasuki Higashimura, et al.