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Impact of oat processing on glycaemic and insulinaemic responses in healthy humans: a randomised clinical trial

  • Thomas M. S. Wolever (a1), Jodee Johnson (a2), Alexandra L. Jenkins (a1), Janice C. Campbell (a1), Adish Ezatagha (a1) and YiFang Chu (a2)...


Oats can be processed in a variety of ways ranging from minimally processed such as steel-cut oats (SCO), to mildly processed such as large-flake oats (old fashioned oats, OFO), moderately processed such as instant oats (IO) or highly processed in ready-to-eat oat cereals such as Honey Nut Cheerios (HNC). Although processing is believed to increase glycaemic and insulinaemic responses, the effect of oat processing in these respects is unclear. Thus, we compared the glycaemic and insulinaemic responses elicited by 628 kJ portions of SCO, OFO, IO and HNC and a portion of Cream of Rice cereal (CR) containing the same amount of available-carbohydrate (23 g) as the oatmeals. Healthy males (n 18) and females (n 12) completed this randomised, cross-over trial. Blood was taken fasting and at intervals for 3 h following test-meal consumption. Glucose and insulin peak-rises and incremental AUC (iAUC) were subjected to repeated-measures ANOVA using Tukey’s test (two-sided P<0·05) to compare individual means. Glucose peak-rise (primary endpoint, mean (sem) mmol/l) after OFO, 2·19 (sem 0·11), was significantly less than after CR, 2·61 (sem 0·13); and glucose peak-rise after SCO, 1·93 (sem 0·13), was significantly less than after CR, HNC, 2·49 (sem 0·13) and IO 2·47 (sem 0·13). Glucose iAUC was significantly lower after SCO than CR and HNC. Insulin peak rise was similar among the test meals, but insulin iAUC was significantly less after SCO than IO. Thus, the results show that oat processing affects glycaemic and insulinaemic responses with lower responses associated with less processing.


Corresponding author

*Corresponding author: Dr T. M. S. Wolever, email


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1. Tosh, SM & Chu, YF (2015) Systematic review of the effect of processing of whole-grain oat cereals on glycaemic responses. Br J Nutr 114, 12561262.
2. Jenkins, DJA, Wolever, TMS, Taylor, RH, et al. (1981) Glycemic index of foods: a physiological basis for carbohydrate exchange. Am J Clin Nutr 34, 362366.
3. Jenkins, DJA, Wolever, TMS, Jenkins, AL, et al. (1983) The glycaemic index of foods tested in diabetic patients: a new basis for carbohydrate exchange favouring the use of legumes. Diabetologia 24, 257264.
4. Wolever, TMS, Katzman-Relle, L, Jenkins, AL, et al. (1994) Glycaemic index of 102 complex carbohydrate foods in patients with diabetes. Nutr Res 14, 651669.
5. Wood, PJ (1986) Oat β-glucan: structure, location and properties. In Oats: Chemistry and Technology, pp. 121152 FH Webstger, editor]. St Paul, MN: AACC Inc.
6. Wood, PJ, Braaten, JT, Scott, FW, et al. (1994) Effect of dose and modification of viscous properties of oat gum on plasma glucose and insulin following an oral glucose load. Br J Nutr 72, 731743.
7. Wood, PJ, Beer, MU & Butler, G (2000) Evaluation of role of concentration and molecular weight of oat β-glucan in determining effect of viscosity on plasma glucose and insulin following an oral glucose load. Br J Nutr 84, 1923.
8. Regand, A, Tosh, SM, Wolever, TM, et al. (2009) Physicochemical properties of beta-glucan in differently processed oat foods influence glycemic response. J Agric Food Chem 57, 88318838.
9. Biörklund, M, van Rees, A, Mensink, RP, et al. (2005) Changes in serum lipids and postprandial glucose and insulin concentrations after consumption of beverages with β-glucans from oats or barley: a randomized dose-controlled trial. Eur J Clin Nutr 59, 12721281.
10. Maki, KC, Galant, R, Samuel, P, et al. (2007) Effects of consuming foods containing oat β-glucan on blood pressure, carbohydrate metabolism and biomarkers of oxidative stress in men and women with elevated blood pressure. Eur J Clin Nutr 61, 786795.
11. Tapola, N, Karvonen, H, Sarkkinen, E, et al. (2005) Glycemic responses of oat bran products in type 2 diabetic patients. Nutr Metab Cardiovasc Dis 15, 255261.
12. Kabir, M, Oppert, JM, Vidal, H, et al. (2002) Four-week low glycemic index breakfast with a modest amount of soluble fibers in type 2 diabetic men. Metabolism 51, 819826.
13. Jenkins, AL, Jenkins, DJA, Zdravkovic, U, et al. (2002) Depression of the glycemic index by high levels of beta-glucan fiber in two functional foods tested in type 2 diabetes. Eur J Clin Nutr 56, 622628.
14. Jenkins, DJA, Wolever, TMS, Leeds, AR, et al. (1978) Dietary fibres, fibre analogues, and glucose tolerance: importance of viscosity. Br Med J 1, 13921394.
15. Rosenthal, SM & Ziegler, EE (1929) The effect of uncooked starches on the blood sugar or normal and of diabetic subjects. Arch Int Med 44, 344350.
16. Jenkins, DJA, Wesson, V, Wolever, TMS, et al. (1988) Wholemeal versus wholegrain breads: proportion of whole or cracked grain and the glycaemic response. Br Med J 297, 958960.
17. Rebello, CJ, Chu, Y, Johnson, WD, et al. (2014) The role of meal viscosity and oat beta-glucan characteristics in human appetite control: a randomized crossover trial. Nutr J 13, 49.
18. Wolever, TMS & Jenkins, DJA (1986) The use of the glycemic index in predicting the blood glucose response to mixed meals. Am J Clin Nutr 43, 167172.
19. Wolever, TMS (2004) Effect of blood sampling schedule and method calculating the area under the curve on validity and precision of glycaemic index values. Br J Nutr 91, 295300.
20. University of Sydney (2017) GI foods advanced search. (accessed August 2018).
21. Wolever, TMS, van Klinken, BJ-W, Spruill, SE, et al. (2016) Effect of serving size and addition of sugar on the glycemic response elicited by oatmeal: a randomized, cross-over study. Clin Nutr ESPEN 16, 4854.
22. Christensen, NJ, Ørskov, H & Hansen, AP (1972) Significance of glucose load in oral glucose tolerance tests. Acta Med Scand 192, 337342.
23. Wolever, TMS & Bolognesi, C (1996) Source and amount of carbohydrate affect postprandial glucose and insulin in normal subjects. J Nutr 126, 27982806.
24. Lee, BM & Wolever, TMS (1998) Effect of glucose, sucrose and fructose on plasma glucose and insulin responses in normal humans: comparison with white bread. Eur J Clin Nutr 52, 924928.
25. Wolever, TMS, Gibbs, AL, Spolar, M, et al. (2006) Equivalent glycemic load (EGL): a method for quantifying the glycemic responses elicited by low carbohydrate foods. Nutr Metab (Lond) 3, 33.
26. Wolever, TMS (2006) The Glycaemic Index: A Physiological Classification of Dietary Carbohydrate. Wallingford, UK: CABI.
27. Wolever, TMS, Vorster, HH, Björk, I, et al. (2003) Determination of the glycaemic index of foods: interlaboratory study. Eur J Clin Nutr 57, 475482.
28. Andersson, AAM & Börjesdotter, D (2011) Effects of environment and variety on content and molecular weight of β-glucan in oats. J Cereal Sci 54, 122128.
29. Herrera, MP, Gao, J, Vasanthan, T, et al. (2014) β-Glucan content, viscosity, and solubility of Canadian grown oat as influenced by cultivar and growing location. Can J Plant Sci 96, 183196.
30. Després, J-P, Lemieux, I & Prud’homme, D (2001) Treatment of obesity: need to focus on high risk abdominally obese patients. Br Med J 322, 716720.
31. European Food Safety Authority (2012) Guidance on the scientific requirements for health claims related to appetite ratings, weight management, and blood glucose concentrations. EFSA J 10, 2604.
32. Health Canada (2013) Draft guidance document on food health claims related to the reduction in post-prandial glycaemic response. (accessed June 2013).
33. Wolever, TMS (2017) Yogurt is a low-glycemic index food. J Nutr 147, 1462S1467S.
34. Rebello, CJ, Johnson, WD, Martin, CK, et al. (2016) Instant oatmeal increases satiety and reduces energy intake compared to a ready-to-eat oat-based breakfast cereal: a randomized crossover trial. J Am Coll Nutr 35, 4149.
35. Anderson, GH, Catherine, NLA, Woodend, DM, et al. (2002) Inverse association between the effect of carbohydrates on blood glucose and subsequent short-term food intake in young men. Am J Clin Nutr 76, 10231030.


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Impact of oat processing on glycaemic and insulinaemic responses in healthy humans: a randomised clinical trial

  • Thomas M. S. Wolever (a1), Jodee Johnson (a2), Alexandra L. Jenkins (a1), Janice C. Campbell (a1), Adish Ezatagha (a1) and YiFang Chu (a2)...


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