Glucose and Insulin responses to barley products: influence of food structure and amylose-amylopectin ratio

Abstract

Postprandial glycemic and insulinemic responses and satiety with various barley products were evaluated in normal subjects. Also studied were the rate of in vitro starch digestion and the content of in vitro resistant starch (RS). Products tested were boiled intact (rice extender) and milled kernels (porridge) from four barley genotypes of Glacier with different amylose-amylopectin ratios (7-44% amylose). All barley products elicited lower metabolic responses and higher satiety scores when compared with white wheat bread. The lente behavior of the boiled flours was probably due to the viscous properties of the beta-glucans. However, the boiled flours produced higher glucose and insulin responses than did the corresponding boiled kernels. The impact of amylose: amylopectin on the metabolic responses was marginal. The high-amylose products released starch more slowly from a dialysis tubing during enzymic incubation of chewed samples compared with the corresponding products with less amylose. The RS content ranged from 0.4% in waxy to 5.6% in the high-amylose flour product (starch basis).

Cereal grains, legumes and diabetes

“…Although a grain variety having a high amylose/amylopectin ratio might be predicted to induce a lower glycaemic response to one containing a higher proportion of amylopectin, the evidence suggests that this is not true in all cases. In the study by Granfeldt et al (1994), an intact grain structure elicited lower glucose and insulin responses than the ground meals. Thus, the effect on measures of carbohydrate metabolism determined by structure and possibly particle size appears to be appreciably greater than the effect of starch type.…”

“…The areas under the 3 h plasma glucose curves were not different among rice varieties, although the 25% amylose rice induced a lower insulin response compared with the rice varieties containing less amylose (Goddard et al, 1984). Four varieties of barley containing 7, 33, 42 and 44% amylose as a percentage of starch were fed to healthy adults either as boiled whole kernels (all four varieties) or as ground barley porridge (the 33 and 42% varieties) (Granfeldt et al, 1994). Despite a large variation in the amylose contents, the effect on plasma glucose and insulin responses was marginal when making comparisons among kernel meals or between the ground meals.…”

Muesli with 4 g oat β-glucans lowers glucose and insulin responses after a bread meal in healthy subjects

“…In the present study we seem to have found a critical level, 4 g of b-glucans, for a significant decrease in glucose and insulin responses after a 50 g carbohydrate portion, in healthy people. We have previously shown that the naturally occurring levels in commercially available oat breakfast products like porridge or flaked cereals do not affect glucose and insulin responses (Granfeldt et al, 1994(Granfeldt et al, , 1995b. Thus, both a portion of oat flakes, and of oat porridge (50 g available carbohydrates) containing approximately 2.5 g b-glucans gave equally high glucose and insulin responses as white wheat bread.…”

“…Various studies have demonstrated positive acute effect of low-GI food, for example, increased satiety in healthy subjects (Granfeldt et al, 1994;Liljeberg and Björck, 1998;Ö stman et al, 2005) and decreased voluntary food intake in obese subjects (Ludwig, 1999). Further medium-to long-term studies in obese subjects are at hand, for example, the findings that a low-GI diet reduced fasting insulin levels in parallel to a weight loss in obese women in a 12-week study (Slabber et al, 1994), or that the body weight of obese children decreased more after a low-GI diet compared to a standard reduced fat diet in a 15-month study (Spieth et al, 2000) In the EURODIAB Complications Study of nearly 3000 adults with type I diabetes, consumption of lower GI diet was found to be related to lower measures of intra-abdominal fat mass and total body fat (waist-to-hip ratio and waist circumference) independently of carbohydrate, fat or fibre intake (Toeller et al, 2001).…”

Delayed gastric emptying rate may explain improved glycaemia in healthy subjects to a starchy meal with added vinegar

“…In contrast, pasta products (Granfeldt & Bjo Èrck, 1991) and certain rice display GI in the lower range (GI 45 ±70). The GI of legume products (Dilawari et al, 1981;Tovar et al, 1992) and intact cereal grains (Granfeldt et al, 1994;Jenkins et al, 1988b) have been found to be very low, and in fact among the lowest reported for starchy foods (GI 15± 65). In a few studies it has been demonstrated that the organic acids formed during fermentation of, for instance, vegetables (Torsdottir et al, 1992) and bread (Liljeberg et al, 1995) may signi®cantly improve the glucose tolerance to starch.…”