A novel konjac rice formula with glucomannan and tapioca starch improve postprandial glycemic response – a randomized single-blind clinical trial

• Published in: Nutrition and food science Vol. 54; no. 8; pp. 1437 - 1450
• Main Authors: Wilianto, Yufita Ratnasari, Tjahjono, Yudy, Foe, Kuncoro, Wijaya, Sumi, Ervina, Martha, Setiadi, Diga Albrian, Wihadmadyatami, Hevi, Novita Dewi, Bernadette Dian, Wijaya, Hendy
• Format: Journal Article
• Language: English
• Published: Bradford Emerald Publishing Limited 25-10-2024; Emerald Group Publishing Limited
• Subjects: Blindness; Blood; Blood glucose; Blood levels; Carbohydrates; Chronic illnesses; Clinical outcomes; Clinical trials; Diabetes; Diabetes mellitus (non-insulin dependent); Diet; Dietary fiber; Effectiveness; Exercise; Flora; Flour; Food; Glucose; Glucose monitoring; Glycemic index; Grain; Health risks; Insulin resistance; Long-term effects; Microorganisms; Organoleptic properties; Palatability; Parameters; Public health; Rice; Satiety; Sensory properties; Sugar; Tapioca; Traditions; Southeast Asia; Indonesia; Konjac; Glycemic index; Tapioca; Rice; Glucomannan
• ISSN: 0034-6659; 0034-6659; 1758-6917
• DOI: 10.1108/NFS-12-2023-0290

Purpose
Due to white rice’s association with diabetes and other chronic diseases in many Asian countries, many industries are working to develop high-fiber rice substitutes with similar organoleptic characteristics. Konjac rice (KR) is a promising option, but maintaining its optimal fiber content for health benefits while preserving its ideal sensory profile remains a challenge. This study aims to investigate whether a KR formula, combining tapioca flour and glucomannan gel, possesses similar organoleptic attributes to white rice while preventing glycemic response elevation.
Design/methodology/approach
In a six-week randomized single-blind clinical trial, 13 normoweight nondiabetic subjects received varying konjac-based rice and white rice ratios. Blood glucose levels were measured at intervals, and glycemic response was assessed using incremental area under the curve (iAUC). Visual analog scale gauged satiety, and organoleptic properties were evaluated.
Findings
Substituting white rice with pure and partial konjac-based rice significantly lowered postprandial blood sugar levels and glycemic response (p = 0.002). iAUC for pure KR and KR 1:1 was notably lower than white rice (p = 0.002). Subjects reported a sense of fullness comparable to white rice, with no significant organoleptic score differences (p = 0.260).
Research limitations/implications
The study’s generalizability is compromised due to the limited number of participants, impacting external validity. The examined parameters offer a rough understanding of konjac grain’s impact on postprandial glycemic responses but do not elucidate underlying mechanisms or the duration of its inhibitory effect on glucose absorption. Long-term effects on metabolic, hormonal parameters and the colon’s microbial flora composition and function remain unexplored, constraining comprehensive insights into konjac grain’s extended implications.
Practical implications
This study introduces a novel KR formula to address the escalating diabetes risks associated with white rice consumption. Substituting white rice with KR significantly reduces postprandial blood sugar levels, highlighting its potential in preventing type 2 diabetes (T2D). Tapioca flour enhances palatability, making KR a viable option. While promising, long-term effectiveness and safety require further research, emphasizing comprehensive lifestyle interventions. The study contributes valuable insights to innovative dietary strategies for prevalent health conditions, emphasizing the need for ongoing efforts in public health.
Social implications
White rice, a staple in Asian societies, is linked to a heightened risk of T2D due to increased production and inadequate dietary fiber. This connection contributes to the economic burden on governments through health insurance and lost productivity. Encouraging alternatives rich in fiber can mitigate this burden, offering a socioeconomically beneficial solution to preventable chronic diseases.
Originality/value
This trial demonstrates konjac-based rice’s potential in curbing glycemic responses, hinting at its role in preventing T2D. Glucomannan’s viscosity, satiety induction and potential gut health impact are highlighted. Further research is warranted for long-term effectiveness and safety. These findings contribute to the growing evidence supporting glucomannan as a valuable tool in addressing prevalent health conditions.