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

Abstract

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.

Foods Consumed with Rice that Elicit a Reduction in Glucose Response among Healthy Individuals

“…steel-cut oats resulted in a much lower glucose iAUC compared to highly processed oats such as Honey Nut Cheerios (HNC). 39 The addition of dried fruit taken together with rice meals also has a beneficial effect on reducing the postprandial GR. 40 The combination of kiwi fruit with rice compared to rice alone were also found to be able to lower postprandial GR 41…”

Effect of a regular consumption of traditional and roasted oat and barley flakes on blood lipids and glucose metabolism–A randomized crossover trial

“…Cell walls of the endosperm and aleurone layer of barley and oat grains contain the highest amounts of β-glucan compared to other cereals ( 7 – 9 ). Oat and barley flakes contain an average of 4.6 and 5.2% β-glucan, respectively ( 10 – 12 ). Numerous studies indicated the health-promoting effects of barley and oat and provide the basis for official health claims by the European Food Safety Authority (EFSA) ( 13 – 33 ).…”

Ultra‐processed foods: Processing versus formulation

“…13 As a result of processing, quick oats and rolled oats have a higher glycemic index than steel cut oats. 13 Simple grinding of peanuts to make peanut butter can increase the absorption of fat and thus provide more kilocalories. 14 Fat absorption is even higher when consuming peanut oil.…”

“…Processing itself can have negative effects on nutrient availability of foods and thus on health. Overprocessing of grains can cause an increase in the glycemic index which can impact circulating glucose levels and hemoglobin A1C 13 . As a result of processing, quick oats and rolled oats have a higher glycemic index than steel cut oats 13 .…”

“…Overprocessing of grains can cause an increase in the glycemic index which can impact circulating glucose levels and hemoglobin A1C 13 . As a result of processing, quick oats and rolled oats have a higher glycemic index than steel cut oats 13 . Simple grinding of peanuts to make peanut butter can increase the absorption of fat and thus provide more kilocalories 14 .…”