Postprandial Plasma Lipid Responses To Different Types Of Breads

High-carbohydrate (HC) diets are recommended for lowering the risk of coronary heart disease because they decrease plasma low-density lipoprotein (LDL) cholesterol concentrations. In the study by Queenan et al. (2007), 75 hypercholesterolemic men and women were randomly assigned to either the 6 g/day concentrated oat b-glucan treatment group or the 6 g/ day dextrose (control) treatment group. After 6 weeks, it was observed that 6 g concentrated oat b-glucan per day during this period significantly reduced the total and LDL cholesterol in subjects with elevated cholesterol, and the LDL cholesterol reduction was greater than the change in the control group. In a study comparing the effects of whole wheat bread and b-glucan supplemented oat bread on the lipid profile, the oat-derived b-glucan was found to significantly improve high-density lipoprotein (HDL) cholesterol while diminishing LDL cholesterol and non-HDL cholesterol in overweight individuals with mild

60 50 40 30 20 10

Whole grain Wheat bran rye white

Bread types P = 0 297

3 0 min m 120 min

FIGURE 39.2

Insulinemic effects of different bread types. No significant difference was found between insulinemic effects of four different types of breads. Results are expressed as mean ±SD, n= 121. Source: Reproduced from Mesci, B, Oguz, A, Sagun, H. G, Uzunlulu, M, Keskin, E. B, and Coksert, D. (2008). Dietary breads: Myth or reality? Diabetes Res. Clin. Pract. 81, 68—71.

TABLE 39.2 Glucose, Insulin, C-Peptide, Glucose-Dependent Insulinotropic Polypeptide (GIP), and Glucagon-like Peptide 1 (GLP-1) Responses to the Consumption of Test Breadsj^^H^H^^^^^HI

Refined Wheat

Endosperm

Traditional Rye

High-Fiber

Bread

Rye Bread

Bread

Rye Bread

Glucose (mmol/l)

2.1 ± 0.2

2.0 ± 0.2

2.0 ± 0.1

1.7 ± 0.2

Insulin (pmol/l)

299.2 ± 28.1

206.1 ± 18.8*

220.5 ± 20.8*

222.2 ± 29.1*

C-peptide (nmol/l)

1.9 ± 0.1

1.4 ± 0.1*

1.4 ± 0.1*

1.5 ± 0.1*

GIP (pmol/l)

107.2 ± 7.4

87.7 ± 10.3

59.1 ± 4.6*'**

60.5 ± 5.0*'**

GLP-1 (pmol/l)

28.3 ± 4.7

30.6 ± 6.3

25.9 ± 3.3

26.4 ± 5.4

Source: Reproduced with permission from Juntunen, K. S., Laaksonen, D. E., and Autio, K. (2003). Structural differences between rye and wheat breads but not total fiber content may explain the lower postprandial insulin response to rye bread. Am. J. Clin. Nutr. 78, 957—964.

aRye bread leads to a lower postprandial insulin response compared to the other types of breads. Results are expressed as mean ± SEM; n = 19. Significantly different from refined wheat bread; p < 0.05. Significantly different from endosperm rye bread; p < 0.05.

Source: Reproduced with permission from Juntunen, K. S., Laaksonen, D. E., and Autio, K. (2003). Structural differences between rye and wheat breads but not total fiber content may explain the lower postprandial insulin response to rye bread. Am. J. Clin. Nutr. 78, 957—964.

aRye bread leads to a lower postprandial insulin response compared to the other types of breads. Results are expressed as mean ± SEM; n = 19. Significantly different from refined wheat bread; p < 0.05. Significantly different from endosperm rye bread; p < 0.05.

hypercholesterolemia (Reyna-Villasmil et al., 2007). However, the effects of breads on the blood lipid profile are not as harmless as they were originally thought to be. An unfavorable effect of HC diets is the rise in plasma triacylglycerol concentrations (Coulston et al., 1989; Dreon et al., 1990) resulting from increased rates of very low-density lipoprotein— triacylglycerol secretion (Mittendorfer and Sidossis, 2001). In a study that compared whole wheat brown bread, rice, and roti (a traditional Indian dish) having equal carbohydrate contents with respect to the effects on the blood lipid profile (Ezenwaka and Kalloo, 2005), whole wheat brown bread elicited the highest postprandial triacylglycerol increase among the three foods tested in both diabetic and nondiabetic subjects (Tables 39.3 and 39.4).

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