High Fiber Diet and Diabetes: effect of soluble and insoluble fiber on plasma glucose levels.

Introduction

Obesity associated with low physical activity is a leading cause of type II diabetes mellitus. (Montonen J et al. 2002) Diet and eating habits are major contributing factors in the development of obesity, thus diet is one of the modifiable risk factors that can ultimately lead to or prevent the development of non-insulin dependent diabetes mellitus. (Ventura E. et al 2009) Strong evidence has shown that a high fiber, particularly one that is high in whole grain diet can play a preventative role against developing type II diabetes mellitus. (Montonen J et al 2002) Moreover, low glycemic index, high fiber diets have shown a beneficial effect in controlling diabetes and reducing diabetes occurrence. (Jenkins D. J. A. et al 2008) In addition to significantly lowering values for fasting and postprandial plasma glucose, high-fiber diets have also positively contributed to long-term weight loss and to decrease the risks of cardiovascular disease (CVD) risks. (Lindstrom J et al. 2006)

Types of dietary fiber and their properties

Fiber exists in two forms, soluble and insoluble. Some examples of soluble fibers are pectin, gums ß-glucans and hemicelluloses. Foods that contain soluble fibers are fruits such as oranges and apples. Oats, barley, chickpeas, okra, and legumes also contain soluble fibers. Soluble fibers can adsorb or bind nutrients such as lipids and bile acids and decrease their absorption, which leads to decreased serum lipids. Some of their function is to bind water causing a decrease in transit time and an increase in fecal volume. They also have the ability to form gels that lead to a decrease in nutrient absorption. Examples of dietary fibers classified as insoluble are cellulose, lignin, and some hemicelluloses. Insoluble fibers are generally known to lower the digestive function by decreasing intestinal transit time. Some food sources include wheat bran, whole-grain breads and cereals as well as vegetables such as cabbage, carrots, and brussel sprouts.

Studies on fiber and blood glucose

Literature suggests that the component of fiber that is associated with lowering cholesterol and effects blood glucose and postprandial insulin levels is soluble fiber (Kim H. et al 2009). A study done by Kim et al. tested the insulin response to soluble fiber in overweight individuals with type II diabetes. Results showed that higher consumption of soluble fibers promoted remarkable reduction in insulin responses (P