Dashi is prepared by boiling dried foods such as kelp and bonito for a very short time, and contains amino acids that confer a savoury, umami taste to dishes.
The concentrations of three free amino acids (histidine, glutamate and aspartate) were 10- to 12-fold higher, compared with 15 other free amino acids found in three broths assessed by researchers at Kyoto University.
Based on the component analysis of the three actual broths served in traditional restaurants, a chemically synthesised broth was prepared to investigate their effects on glucose metabolism and digestion.
Seven healthy individuals were enrolled in a four-period crossover study. Participants consumed either hot water, synthesised broth, hot water with rice, or synthesised broth with rice.
Writing in the journal Nutrition, the researchers stated: "Ingesting synthesised broth with rice resulted in a rapid rise in plasma glucose in an early postprandial phase compared with that by ingesting water with rice.
"Ingesting synthesised broth with rice resulted in a significantly higher gastric emptying coefficient than that after rice with water."
Future studies
They added that the findings were especially relevant for people suffering from functional dyspepsia, symptoms of which include early satiation and pain or burning in the epigastrium.
"A clinically interesting finding of the present study is that the common broth in the Japanese diet may be a dietary option for patients with functional dyspepsia to alleviate delayed gastric emptying and promote digestion," wrote the researchers.
"Further studies to demonstrate the beneficial effect of broth in patients with functional dyspepsia are required."
They added that, unlike the Mediterranean diet, there are few studies that have assessed the health benefits of the Japanese diet.
They concluded:"The present study sheds light on the function of clear broth, which may have some healthy effects. Our findings suggest that ingestion of the broth of dried kelp and dried bonito may improve gastric motility."
Source: Nutrition
https://doi.org/10.1016/j.nut.2017.08.007
"Effects of three major amino acids found in Japanese broth on glucose metabolism and gastric emptying"
Authors: Fumika Mano, et al.