Soy products are well known to possess glycaemic control benefits, while rice bran may also possess a similar property. In this pilot study published in Nutrients, researchers examined the effect on glucose and insulin responses resulting from soy milk fortified with rice bran.
Led by researchers from the National University of Singapore, the team found that consuming rice bran and soy milk (RBS) together with a carbohydrate meal (white bread) resulted in a 17% reduction in glycaemic index (GI) of the meal compared with consumption of bread alone.
“Co-ingestion of low amounts of soy protein with a carbohydrate meal stimulated early-phase insulin secretion and thereby increased blood glucose clearance effectiveness,” commented lead researcher Professor Christiani Jeyakumar Henry.
“Furthermore, rice bran-fortified soy milk reduced the glycaemic response similarly to soy milk with a greater dose of soy protein," Henry added. "Rice bran and its components offer therapeutic potential for glycaemic and insulinaemic control."
Study details
The randomised crossover pilot study analysed data from 17 healthy Asian men who consumed white bread either alone or alongside one of two soy milks differing in rice bran and soy protein content.
Blood sugar and insulin measurements were taken over a period of 3 hours, following bread and/or soy milk intake, said the team.
Part funded by Sunstar Group, Japan - who manufacture the RBS - the study found that when when sugar-free soy milk (SFS) was co-ingested with the bread, the result was not significantly different.
Indeed, the team said both both soy milks also appeared to increase release of insulin in the first half hour after consuming them.
Compared to those consuming white bread alone, glucose to insulin ratios in people consuming the RBS and SFS with the carbohydrate meal were much lower - at 43 and 60 respectively versus 123.
Though the difference in effects between the two soy milks were not statistically significant, the Singapore team emphasised that the RBS was able to achieve the glycaemic control benefits despite a much lower soy protein content than the SFS (3.4 grams per 195 millilitre serving, versus 7.8 grams).
The team believes the combination of soy protein and fibre was the main driver of the glycaemic control benefits produced by the RBS.
However, they noted that rice bran also contains other nutrients like the phytochemical oryzanol, magnesium, and zinc, which may also provide blood sugar management benefits.
“Co-ingestion of rice bran soymilk with carbohydrate meals can be a simple dietary strategy to improve glycaemic control and help in the prevention and management of diabetes,” suggested the team - adding that further large studies are nevertheless needed to replicate these preliminary findings.
Source: Nutrients
Volume 10, issue 4, article no. 449, doi: 10.3390/nu10040449
“Co-Ingestion of Rice Bran Soymilk or Plain Soymilk with White Bread: Effects on the Glycemic and Insulinemic Response”
Authors: Stefan Gerardus Camps, Christiani Jeyakumar Henry et al