The effects of prebiotic bread containing oat ß-glucan and resistant starch on the glycemic index and glycemic load in healthy individuals

Purpose

The enrichment of bread with non-digestible prebiotic ingredients may exert health-promoting effects and provide healthier food choices for those suffering from metabolic diseases, including obesity and diabetes. The purpose of this study was to investigate the effects of ß-glucan and resistant starch incorporation on the glycemic index (GI) and glycemic load (GL) of white bread.

Design/methodology/approach

Seven different formulations of prebiotic bread were produced using different proportions of ß-glucan (0.8, 1 and 1.2 per cent), resistant starch (5.5, 8 and 10.5 per cent) and the combination of resistant starch and ß-glucan in a ratio of 4:0.5.

Findings

The GI and GL of the prebiotic bread prepared with 1 per cent ß-glucan (w/w) were 55.7 and 7.8, respectively, whereas those of the prebiotic bread prepared with 8 per cent resistant starch (w/w) were 64.8 and 8.42, respectively, with both breads having significantly lower GI and GL values than the control (P < 0.05). It was concluded that the incorporation of 1 per cent ß-glucan may be beneficial in producing prebiotic bread with both low GI and low GL.

Originality/value

Although white bread is a main food source in human diet, its high GI and GL make it an unhealthy food choice. The incorporation of ingredients with prebiotic effects, such as ß-glucan and resistant starch, can improve the nutritional value of this product by lowering its GI and GL.

Effects of beta-glucan and resistant starch on wheat dough and prebiotic bread properties

White wheat flour is a poor source of dietary fiber. Therefore a demand exists for enrichment of bread with non-digestible prebiotic ingredients that exert health-promoting effects. In this study, the effects of beta-glucan (BG) and resistant starch (RS) on the dough properties and bread-making characteristics were investigated. The water absorption of doughs increased with increasing BG and RS levels. Also, development time and farinograph quality number of BG-enriched doughs remained similar to that of the control while the doughs stability decreased, and all of these values decreased when the RS was added. BG was more effective in increasing the dough softening than RS. The resistance to deformation, energy, maximum resistance and ratio number values; increased with the addition of RS or BG, but their extensibility was decreased in comparison to the control. Formulation containing BG/RS combination showed the best farinograph (development time, stability) and extensograph (resistance and extensibility) parameters. The application of BG and RS had similar effect on specific volume, and moisture content while it caused a decrease in firmness after 5 days of storage.

The relationship between established coronary risk factors and serum copper and zinc concentrations in a large Persian cohort

INTRODUCTION

The relationship between demographic and biochemical characteristics, including several established coronary risk factors, and serum copper and zinc was assessed in a large Iranian population sample.

MATERIALS AND METHODS

A group of 2233 individuals, 15-65 years of age [1106 (49.5%) males and 1127 (50.5%) females] was recruited from residents of the Greater Khorasan province in northeast of Iran. Demographic data were collected using questionnaires. Coronary risk factors were determined using standard protocols, and trace elements were measured in serum using atomic absorption spectroscopy.

RESULTS

Degree of glucose tolerance and smoking habit were not associated with serum zinc and copper levels. Serum copper levels were significantly higher in obese and hypertensive than in normal subjects (p<0.001). In the whole group and for the female subgroup, serum zinc (p<0.01) and copper (p<0.001) were both significantly lower in individuals with normal versus high levels of low-density lipoprotein cholesterol. A strong positive correlation was found between serum copper and body mass index (BMI) (r=0.85, p<0.001). Weaker positive associations were found between serum copper and calculated 10 years' coronary risk (r=0.11, p<0.001). Serum zinc/copper ratio was strongly inversely associated with calculated 10 years' coronary risk (r=-0.10, p<0.001). The partial Eta squared (PES) values for factors determining serum zinc were hypertension (0.007, p=0.01) and BMI (0.004, p=0.01); and for serum copper, they were gender (0.02, p=0.001), hypertension (0.004, p=0.009), and 10 years' coronary risk for men (0.003, p=0.03) and women (0.002, p=0.07).

CONCLUSION

Significant associations between serum trace element concentrations and several coronary risk factors, including calculated 10 years' coronary risk scores, were found.