It is well known that rhamnan sulfate has various positive physical effects, but its effect in preventing obesity has not been generally known until date. Its effectiveness in attenuating obesity was investigated using obese zebrafish models.
High-calorie feed was administered for two weeks to create obese zebrafish (obese model), which were subsequently divided into two groups. One group was given high-calorie feed only, and the other group was given high-calorie feed supplemented with rhamnan sulfate. Thereafter, and changes in body weight were studied.
A significant body weight attenuation effect was observed in the zebrafish fed with feed containing rhamnan sulfate as compared with those fed with high-calorie feed only.
It became clear that rhamnan sulfate is effective in attenuating obesity.
Dyslipidemia is sometimes caused by obesity. If fatty acid is introduced and new lipogenesis occurs in excess of the capacity to eject fat from the liver, excess fat will accumulate in the liver. Hyperlipidemia is often accompanied by deposition of fat. Using zebrafish, we looked at the effects rhamnan sulfate on deposition of fat in the liver.
Zebrafish fattened with high-calorie feed for two weeks were fed either with high-calorie feed either alone, or supplemented with rhamnan sulfate. The livers of the zebrafish were collected six weeks after ingestion and the extent of deposition of fat in the liver was investigated by means of oil red staining.
Oil red staining results in fat being stained red. In the control group of zebrafish, red-stained areas were not observed, whereas most of the livers of the zebrafish on high-calorie feed were stained red. As compared with the zebrafish that had ingested high-calorie feed, those that had ingested high-calorie feed supplemented with rhamnan sulfate had were found to have fewer red-stained areas.
It was found that ingestion of rhamnan sulfate resulted in suppression of fat deposition in the liver accompanying obesity.