The effect of sodium alginate on nutrient digestion and metabolic responses during both in vitro and in vivo digestion process

Abstract

The purpose of this study was to investigate the contribution of long-term and short-term consumption of sodium alginate on the nutrient digestion and metabolic regulation of rats and to explore their actions on energy intake and glycemic regulation. Results were obtained from both in vitro and animal experiments. Two feeding methods were used to raise rats in two groups to study the influence of consumption of sodium alginate on food intake, gastrointestinal chyme, blood glucose and related hormones, body weight, apparent protein digestibility (APD) and changes in the digestive tract. Our findings showed that the calcium carbonate-containing sodium alginate system formed a gel in stomach conditions, and the formation of gel lowered dextrin and whey protein isolate (WPI) hydrolysis rate in vitro. The short-term results showed that a clear gel mass was observed in the rats’ stomach which could potentially affect distension of the stomach and prolong the gastric emptying time, leading to reduced food intake of the rats in the short time (4 h). By studying the long-term feeding containing sodium alginate in the diet, it was found that the addition of sodium alginate reduced food intake, body weight and APD, the peak value of blood glucose was 10.8 mmol/L, which was about 77% of the peak blood glucose level in the control group, indicating the impaired nutrient digestibility, and the maximal rate at which glucose was entering the blood was reduced. However, the length of the small intestine increased in order to obtain sufficient nutrients for normal growth and metabolism. The results of this research suggested that sodium alginate could potentially be effective in the treatment of metabolic syndrome and obesity in humans.