Estimation of Glycemic Index of a Probiotic Enriched Smoothie Bowl

Abstract

The rising burden of non-communicable diseases, particularly type 2 diabetes, underscores the importance of dietary interventions that modulate postprandial glycemia, with low glycemic index (GI) foods playing a key role in improving insulin sensitivity. While ingredients such as oats, whey protein, and probiotics individually show glycemic benefits, limited evidence exists on their combined effect in a single functional food. This study was undertaken to develop and standardize a probiotic-enriched smoothie bowl, evaluate its sensory acceptability, and estimate its GI in healthy young adults. The research was conducted in three phases: formulation and standardization of the smoothie using oats, whey protein isolate, milk, sugar, and a powdered probiotic blend; sensory evaluation of five variants (R1–R5) by semi-trained subjects and consumers using a 9-point hedonic scale; and GI testing of the most acceptable variant (R5) as per FAO/WHO (1998) protocol. Fifteen healthy participants (18–35 years) consumed the reference food (50 g glucose), the probiotic smoothie, and in a subgroup (n=5), a non-probiotic version, with capillary blood glucose measured at intervals up to 120 minutes for incremental area under the curve (iAUC) calculation. The. GI of the probiotic enriched smoothie variation [38.3 (11.4)] was estimated to be significantly lower than the non probiotic smoothie variation [67.3 (12.4), p=0.063]. The observed differences highlight the distinct impact of probiotic fortification on glycemic outcomes compared to standard and reference foods. In conclusion, the developed probiotic-enriched smoothie bowl was well accepted and demonstrated favorable glycemic properties, suggesting its potential as a functional dietary option for supporting glycemic control.

Introduction

The glycemic index (GI) is a key nutritional measure that indicates how carbohydrate-rich foods affect postprandial (after-meal) blood glucose levels. Defined as the incremental area under the blood glucose response curve (iAUC) after consuming 50 g of available carbohydrates compared to glucose, GI helps guide dietary planning and chronic disease prevention. Low-GI foods improve insulin sensitivity, lipid metabolism, and long-term glycemic control, reducing the risk of type 2 diabetes and cardiovascular disease.

With non-communicable diseases (NCDs)—particularly diabetes—rising rapidly in India (now accounting for 66% of total deaths, WHO 2024), the GI concept provides a scientific framework for developing healthier diets. The GI of foods is influenced by several factors including starch composition (amylose vs. amylopectin), processing, fiber, fat, and protein content, all of which affect digestion and glucose response.

Parallel to this, probiotics—live microorganisms such as Lactobacillus and Bifidobacterium—have shown benefits for gut health, immune modulation, and glycemic control through their effects on intestinal microbiota and insulin sensitivity. Advances like microencapsulation have improved probiotic stability in functional foods. Despite growing availability of probiotic products, little research has examined their impact on glycemic response, especially in composite foods like smoothie bowls.

Study Aim and Methodology

This study aimed to develop and evaluate a probiotic-enriched smoothie bowl and estimate its GI in healthy adults (18–35 years) in Mumbai. The research followed three phases:

1. Product Development: Standardized recipes using oats, milk, whey protein, and a probiotic blend (Lactobacillus and Bifidobacterium, 16 billion CFU).

2. Sensory Evaluation: 18 panelists rated five formulations (R1–R5) on taste, texture, aroma, and appearance using a 9-point hedonic scale.

3. GI Estimation: 15 participants underwent GI testing using the FAO/WHO (1998) protocol. Blood glucose was measured at fasting and post-meal intervals after consuming 50 g glucose (reference), the probiotic smoothie (R5), and a non-probiotic version.

Results

• Sensory Evaluation: R5 achieved the highest overall acceptability across sensory attributes.

• Glycemic Index Testing: The probiotic smoothie (R5) showed a lower and more gradual blood glucose rise than both the glucose reference and the non-probiotic version, indicating a lower GI.

• These findings suggest that probiotic enrichment may contribute to better postprandial glycemic control compared to similar non-probiotic formulations.

Conclusion

The probiotic-enriched smoothie bowl developed in this study was well accepted and classified as a low-GI food. Our findings demonstrated that the combination of oats, whey protein, and probiotics worked synergistically to reduce postprandial blood glucose levels compared to the non-probiotic variation. The results suggest that such functional food formulations may serve as practical dietary options for supporting glycemic control in young adults who often rely on fast foods, packaged snacks, and sugary beverages due to convenience and taste. Future research with larger, more diverse populations and longer follow-up periods is needed to confirm these benefits and explore the potential role of functional probiotic enriched smoothie bowls in dietary management of metabolic health.

References

[1] Wolever TMS, Jenkins DJA, Jenkins AL & Josse RG (1991): The glycemic index: methodology and clinical implications. Am. J. Clin. Nutr. 54, 846 – 854. [2] Jenkins, D. J. A., Kendall, C. W. C., Augustin, L. S. A., Franceschi, S., Hamidi, M., Marchie, A., Jenkins, A. L., & Axelsen, M. (2002). Glycemic index: Overview of implications in health and disease. The American Journal of Clinical Nutrition, 76(1), 266S–273S. https://doi.org/10.1093/ajcn/76.1.266S [3] Brouns, F., Björck, I., Frayn, K. N., Gibbs, A. L., Lang, V., Slama, G., & Wolever, T. M. S. (2005). Glycaemic index methodology. Nutrition Research Reviews, 18(1), 145–171. [4] WHO. (2024). Noncommunicable diseases. [5] https://www.who.int/news-room/fact-sheets/detail/noncommunicable-diseasesICMR, PHFI & IHME. (2017). India: Health of the Nation\'s States—The India State-Level Disease Burden Initiative. https://phfi.org/india-health-of-the-nations-states/ [6] Tandon, N., et al. (2018). The increasing burden of diabetes and variations among the states of India: The Global Burden of Disease Study 1990–2016. The Lancet Global Health, 6(12), e1352–e1362. [7] Eleazu CO. The concept of low glycemic index and glycemic load foods as panacea for type 2 diabetes mellitus; prospects, challenges and solutions. Afr Health Sci. 2016 Jun;16(2):468-79. doi: 10.4314/ahs.v16i2.15. PMID: 27605962; PMCID: PMC4994556. https://pmc.ncbi.nlm.nih.gov/articles/PMC4994556/ [8] Latif A, Shehzad A, Niazi S, Zahid A, Ashraf W, Iqbal MW, Rehman A, Riaz T, Aadil RM, Khan IM, Özogul F, Rocha JM, Esatbeyoglu T, Korma SA. Probiotics: mechanism of action, health benefits and their application in food industries. Front Microbiol. 2023 Aug 17;14:1216674. doi: 10.3389/fmicb.2023.1216674. Erratum in: Front Microbiol. 2024 Feb 14;15:1378225. doi: 10.3389/fmicb.2024.1378225. PMID: 37664108; PMCID: PMC10470842. https://pmc.ncbi.nlm.nih.gov/articles/PMC10470842/#sec1 [9] Hill C, Guarner F, Reid G, Gibson GR, Merenstein DJ, Pot B, Morelli L, Canani RB, Flint HJ, Salminen S, Calder PC, Sanders ME. Expert consensus document. The International Scientific Association for Probiotics and Prebiotics consensus statement on the scope and appropriate use of the term probiotic. Nat Rev Gastroenterol Hepatol. 2014 Aug;11(8):506-14. doi: 10.1038/nrgastro.2014.66. Epub 2014 Jun 10. PMID: 24912386. https://pubmed.ncbi.nlm.nih.gov/24912386/ [10] Moroti C, Souza Magri LF, de Rezende Costa M, Cavallini DC, Sivieri K. Effect of the consumption of a new symbiotic shake on glycemia and cholesterol levels in elderly people with type 2 diabetes mellitus. Lipids Health Dis. 2012 Feb 22;11:29. doi: 10.1186/1476-511X-11-29. PMID: 22356933; PMCID: PMC3305430. https://pmc.ncbi.nlm.nih.gov/articles/PMC3305430/ [11] Rahman MS, Emon DD, Toma MA, Nupur AH, Karmoker P, Iqbal A, Aziz MG, Alim MA. Recent advances in probiotication of fruit and vegetable juices. J Adv Vet Anim Res. 2023 Sep 30;10(3):522-537. doi: 10.5455/javar.2023.j706. PMID: 37969792; PMCID: PMC10636081. https://pmc.ncbi.nlm.nih.gov/articles/PMC10636081/#sec15 [12] FAO/WHO. (1998). Carbohydrates in human nutrition. Report of a joint FAO/WHO expert consultation. FAO Food and Nutrition Paper 66. [13] Zhang K, Dong R, Hu X, Ren C, Li Y. Oat-Based Foods: Chemical Constituents, Glycemic Index, and the Effect of Processing. Foods. 2021 Jun 7;10(6):1304. doi: 10.3390/foods10061304. PMID: 34200160; PMCID: PMC8229445. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8229445/ [14] Petersen BL, Ward LS, Bastian ED, Jenkins AL, Campbell J, Vuksan V. A whey protein supplement decreases post-prandial glycemia. Nutr J. 2009 Oct 16;8:47. doi: 10.1186/1475-2891-8-47. PMID: 19835582; PMCID: PMC2766379. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2766379/ [15] Khalili L, Alipour B, Asghari Jafar-Abadi M, Faraji I, Hassanalilou T, Mesgari Abbasi M, Vaghef-Mehrabany E, Alizadeh Sani M. The Effects of Lactobacillus casei on Glycemic Response, Serum Sirtuin1 and Fetuin-A Levels in Patients with Type 2 Diabetes Mellitus: A Randomized Controlled Trial. Iran Biomed J. 2019 Jan;23(1):68-77. doi: 10.29252/.23.1.68. Epub 2018 May 27. PMID: 29803203; PMCID: PMC6305821. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6305821/sec1-3title [16] Ruan Y, Sun J, He J, Chen F, Chen R, Chen H. Effect of Probiotics on Glycemic Control: A Systematic Review and Meta-Analysis of Randomized, Controlled Trials. PLoS One. 2015 Jul 10;10(7):e0132121. doi: 10.1371/journal.pone.0132121. PMID: 26161741; PMCID: PMC4498615. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4498615/ [17] Li G, Feng H, Mao XL, Deng YJ, Wang XB, Zhang Q, Guo Y, Xiao SM. The effects of probiotics supplementation on glycaemic control among adults with type 2 diabetes mellitus: a systematic review and meta-analysis of randomised clinical trials. J Transl Med. 2023 Jul 6;21(1):442. doi: 10.1186/s12967-023-04306-0. PMID: 37415167; PMCID: PMC10324246. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10324246/Sec2title [18] Wang X, Chen L, Zhang C, Shi Q, Zhu L, Zhao S, Luo Z, Long Y. Effect of probiotics at different intervention time on glycemic control in patients with type 2 diabetes mellitus: a systematic review and meta-analysis. Front Endocrinol (Lausanne). 2024 Jul 24;15:1392306. doi: 10.3389/fendo.2024.1392306. PMID: 39114293; PMCID: PMC11303337. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11303337/s2title [19] Ejtahed HS, Mohtadi-Nia J, Homayouni-Rad A, Niafar M, Asghari-Jafarabadi M, Mofid V. Probiotic yogurt improves antioxidant status in type 2 diabetic patients. Nutrition. 2012 May;28(5):539-43. doi: 10.1016/j.nut.2011.08.013. Epub 2011 Nov 29. PMID: 22129852. https://pubmed.ncbi.nlm.nih.gov/22129852/ [20] Rittiphairoj, T., Pongpirul, K., Janchot, K., Mueller, N. T., & Li, T. (2020). Probiotics contribute to glycemic control in patients with type 2 diabetes mellitus: A systematic review and meta-analysis. Advances in Nutrition https://www.researchgate.net/publication/346574563_Probiotics_Contribute_to_Glycemic_Contr ol_in_Patients_with_Type_2_Diabetes_Mellitus_A_Systematic_Review_and_Meta-Analysis

Copyright

Copyright © 2025 Ms. Irika Goyal , Dr. Panchali Moitra . This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.