Information About Carbohydrates - Guide to Different Types of Carbs and Their Effects on Blood Sugar Metabolism

Carbs in Food
Glycemic Index GI of Carbs
Glycemic Load of Carbs
GI Diet - Low GI Diet

Information About Carbs | Carbohydrates Guide
Carb Science | Synthesis of Carbohydrates | Benefits of Carbs

Carbohydrates - Introduction

What Are Carbohydrates? - Monosaccharides - Disaccharides - Oligosaccharides - Polysaccharides - Starch - Sugars

Nutrients

Carbohydrates are macronutrients - foods we need to eat in reasonably large quantities, unlike vitamins and minerals, which are micronutrients and necessary in only small amounts. The two other macronutrients are protein and fat. Carbs are easily converted to energy by the body, so they supply most of our energy needs. There are basically two main classes of carbohydrate - simple carbs and complex carbs - although this classification of carb-types has been superceded by the Glycemic Index (GI) and Glycemic Load (GL), see below.

Types of Carbs

Simple carbs are sugars, like glucose, fructose and lactose. Common sources include table sugar (sucrose), boiled sweets, syrups and honey.

Complex carbs are either starches, or indigestible dietary fiber. Common sources of starches include, bread, pasta, rice, beans and some vegetables. Common sources of dietary fiber are fruits, vegetables, beans, and the indigestible parts of wholegrains like wheat bran and oatbran. Complex carbohydrate is rich in Nutrition and micronutrients like: Vitamins, Minerals and Phytochemicals.

At present, roughly speaking, about 55 percent of the carbohydrates we eat are starchy complex carbs, about 5 percent are dietary fiber (another type of complex carb) and about 40 percent are sugary simple carbs.

Carbohydrates and Glucose

To understand the importance of carbohydrates in our diet, and how carbs differ from (say) protein and fats, remember two things:

• The human body runs on glucose. Therefore all foods need to be converted into glucose before they can provide energy.
• Carbohydrates are more readily converted into glucose than protein or fat, and may be considered the body's "preferred" source of energy.

Note: Carbs may be a very efficient source of energy, but this doesn't mean that carbs are more important than fats or protein. Indeed, both fat and protein are absolutely vital for good health, and without a balanced diet of carbs, fat and protein, the human body quickly becomes malnourished. Also, it's important to realize that nearly all foods (except for oils/fats) contain a mixture of carbs, protein and fat.

Effects of Simple or Complex Carbohydrates
on Blood Sugar

Due to their differing chemical structures, simple carbs and complex carbs affect the body in different ways.

Simple carbs (with the exception of fructose, fruit sugar) are basically sugars (glucose) so they are immediately absorbed into the bloodstream, causing a rise in blood-sugar levels. Because blood sugar-levels must be kept within a certain range, the body responds by telling the pancreas to secrete insulin into the digestive system. Why? Because insulin helps to "mop up" excess blood sugar and disperse it to other parts of the body. Unfortunately, the pancreatic gland typically "overreacts" to this sudden rise in blood sugar (thinking a huge amount of food has been eaten) and secretes too much insulin. Result? Within an hour or so, the insulin has mopped up too much blood sugar, so levels drop too far and this triggers hunger. This rapid rise and fall in blood sugar levels caused by excess production of insulin, is not good for our health or our eating habits. Over time, these "sugar spikes" can lead to impaired glucose tolerance, insulin insensitivity and type 2 diabetes. See also Diabetes information

By comparison, complex carbs need more time to be broken down into glucose. So they don't raise blood sugar levels as fast as simple carbs. This is why nutritionists recommend that we restrict our consumption of simple carbohydrates and eat complex carbohydrates instead.

Very complex carbohydrate (dietary fiber) has such a complicated chemical structure that the human body cannot metabolize it (break it down into glucose or other nutrients) at all. So it passes through the body mostly undigested. However, fiber remains very important for both health and weight control because it helps the body to process waste efficiently and helps us to feel fuller for longer. Fiber also helps protect us against some serious diseases, including various cancers.

Rating Carbohydrate Foods by the Glycemic Index

Recently, the Glycemic Index (GI) has become the benchmark for classifying carbohydrates. The glycemic index is a measure of how rapidly a particular food causes blood sugar to rise, compared with glucose. Foods are divided into high, medium or low glycemic index foods.

Although a valuable tool, especially for diabetics, the glycemic index confines itself to measuring a standard amount of carbs (50g). Since some foods contain only a small percentage of carbs, their glycemic index value may not be as relevant as their Glycemic Load, which takes into account portion size and carb content.