CORRELATION BETWEEN GLYCEMIC INDEX AND STARCH CONTENT

CORRELATION BETWEEN GLYCEMIC INDEX AND STARCH CONTENT

ABSTRACT: Food consumed in the body has become a major problem in society with regards to carbohydrates and starch contents. Glycemic index (GI) helps to determine the number of carbohydrates in a portion of a particular food and how it affects blood glucose in the body. Carbohydrates with a low GI value (55 or less) are more slowly digested, absorbed and metabolized and cause a lower and slower rise in blood glucose and, therefore usually, insulin levels. Starch or amylum is a polymeric carbohydrate consisting of numerous glucose units joined by glycosidic bonds. It has also resulted in some critical health risks from dietary foods. An increase or decrease of the blood glucose can cause many health risks which is why the correlation between glycemic index and starch contents of the dietary food is necessary. In this study, careful laboratory analysis was carried out on some food samples in which the results were interpreted. Proximate analysis, Starch contents, Amylose, and amylopectin contents were analyzed in a laboratory for ten food samples which are rice, corn, sweet potatoes, yam, cassava, plantain, semovita, noodles, bread and spaghetti in their processed and unprocessed states. The proximate analysis shows that the samples contain mainly carbohydrates with an average composition of 73.27% with regards to a range of 61.7 – 68.8%. Bread has the least carbohydrate with 61.7% while rice has the highest carbohydrate 78.8%. The average moisture, protein, fat, fiber and ash content for the unprocessed samples were: 8.4, 4.1, 2.9, 75.3, 6.9 and 2.2 respectively. While for the processed samples were: 10.5, 4.2, 3.0, 73.3, 6.7 and 2.2. The coefficient of correlation (r) between starch content and glycemic index is + 0.9047. Spaghetti has the highest starch content and yam with the least starch content as 32.6 and 21.7 respectively. This shows that starch content increases while the glycemic index increases for the unprocessed food samples. The coefficient of correlation ® for processed food samples is +0.783089. For the processed food samples, Noodles has the least with 29.7% while spaghetti has the highest starch content of 47.2% The diet evaluated in this study was chosen to signify the nutrient inconsistency that matures Nigerians ingest. With this research work, producers and consumers can understand what is contained in a portion of a particular food and the range of consumption to prevent health risks. Producers can also try out more foods with a low Glycemic index for consumption.

CHAPTER ONE

INTRODUCTION

Background of Study

In current times, it is apparent that major health threats and safeties are linked with nutritional option. Some starchy diets break down speedily secreting glucose into the blood for circulation, however some carbohydrate diets are processed gradually discharging glucose steadily into the blood for circulation (Jenkins et al., 1994).  The statistical measure used to specify how quickly and high a certain diet can increase the blood glucose value is identified as glycemic index.  Glycemic index is ranked as one to hundred (1-100).  Diet that elevates the blood glucose value rapidly after consumption is seen as high glycemic index diet and is usually given a rate of 70 upwards, while food that discharges glucose steadily into the blood for circulation is recognized as low glycemic index and is rated as 55 and lower (Brand-Miller et al., 1996).

Studies done on the value of carbohydrate (CHO) foods has in the last years started to incline towards fats (Jenkins et al., 1994). Great epidemiological researches have been linked to a glycemic reaction to chronic illnesses by connecting decreased glycemic index (GI) or glycemic load (GL) to foods with several health benefits (Longo et al., 1998). Thus carbohydrate foods find themselves front-and-center in a nutritional controversy. No longer are they viewed merely as a staple or as a source of energy, but rather they have been added to a list of food components to be evaluated when deciding how much and which type to include in the diet. Thus the GI/GL of some diets may be more about what is or is not present with the CHO rather than the glycemic effect of the CHO (Björck et al., 2000).

Sicknesses have been linked with carbohydrate-rich diets that have a high glycemic Index, starchy contents and increased digestibility level. The key nutritive organization of starches is to distinguish among the processed and the engrossed in the small intestine, availing carbohydrate to the body cells (accessible carbohydrates, ‘‘glycemic carbohydrates’’), and others transitory to the large intestine, provide a substrate for the colon microflora, that is dietary fiber. The glycemic index (GI) notion was presented by Jenkins et al. in 1981. the glycemic index is well-defined as the increment in blood sugar level ensuing consumption of 50g of accessible starch as established on a summit organized by Swedish Nutrition Foundation (SNF) 2223 August 2003.

Another metanalysis by Barclay et al.,1999 suggested that lower GI/GL diets might similarly be beneficial in the inhibition of type 2 DM, a type of DM characterized by insulin resistance and the comparative absence of insulin secretion.

The glycemic index is the measure of immediate influence on plasma glucose levels after food consumption. It is shown as a ratio of the increment of glucose area below the curvature (iAUC) of a trial food with references to standard foods (white bread or glucose) constituting the same available carbohydrates (Salmerón et al., 1997).

1. Approximately 104 million individuals internationally are plagued with Diabetes. This number is increasing every day. Diabetes is a standard public health syndrome (Seal et al., 2003). Food is the major foundation of diabetes maintenance as defined in thorough control. The key emphasis in the dietary management of diabetes to enhance glycemic management is to harmonize nutrient ingestion by endogenous and/or exogenous insulin value (Heacock et al., 2004). Factually, efforts to manage glycemic reaction to food have been made, especially carbohydrate-rich foods, as well as usage of actual little carbohydrate and inadequate diet, synthetic sweetener, and pharmacological supplies which include quick performing insulin and carbohydrate absorption preventions (Heacock et al., 2004). Among Nigerians, the nature of food consumed by the individuals is mainly carbohydrate gotten from roots and tubers or cereals (grain). Potential studies propose small glycemic index foods can decrease the threat of diabetes, metabolic-condition, cardiovascular-syndrome and perhaps other forms of cancer (Liu et al., 2000, Salmeron et al; 1997). The overall carbohydrate in the diet appears to trump the GI or GL of the diet when considering fuel for exercise. For the meal before endurance exercise, data indicate there may be a competitive advantage to selecting low-to-moderate GI/GL foods, and limited data indicating an advantage of a higher GI/GL diet or food for replenishing glucose after exercise (Bornet et al., 1987; Wolever et al., 1996).

Therefore, the requirement for further study of the Glycaemic Index of traditionally consumed diets to develop information that will proficiently facilitate the usage of Glycaemic Index alongside additional nutritional endorsements in the controlling, managing and inhibition of illnesses.

Problem Statement

The amount of sugar (blood glucose) in the body is related to many body functions. This blood glucose depends on the starch contents and glycemic index of the food especially carbohydrate foods. Blood glucose (high or low) has been linked to many-body ailments such as diabetes, high blood pressure (HBP), low blood pressure (LBP), cancer. Hence the need to investigate the correlation between glycemic index, starch content and the corresponding blood glucose level.

Aim and Objectives of the Study

The research work aims to ascertain the correlation between glycemic index and starch content of selected food substances. The specific objectives include;

1. To determine the proximate contents of selected food samples
2. To ascertain the starch contents of selected food samples.
3. To determine amylose: amylopectin ratios in the food samples.
4. To establish the correlation between the glycemic index and the starch content of selected food samples.

Scope of the Study

The study is limited to the top ten carbohydrate food samples representing the most consumed food samples in Nigeria. Proximate analysis was carried out on the samples to ascertain its nutritional content, starch contents, amylose: amylopectin ratios of all the samples were also determined.

Significance of the Study

Diet is the major foundation of diabetes management as defined in severe controlling. The key concentration in dietary supervision of diabetes is to enhance glycemic regulation by harmonizing nutrient intake with endogenous and/or exogenous insulin value (Heacock et al., 2004). There have been several established profits of the Glycaemic index in nutrition which this study can provide.

This result will help nutritionists in providing dietary advice to people with health challenges as well as normal people for longevity. The result will influence food producers and manufacturers to improve better level of low Glycemic index of foods from local farm yield. The findings would have obvious significance in articulating cogent nutritive and beneficial aims for diabetic patients and others with medical circumstances requiring carbohydrate constraint.