Basic info on ''Carbohydrates''
Carbohydrates in Food:
Carbs are one of three main nutrients in food, the others being fats and protein. There are three common types of carbs in foods: (1) Sugar; (2) Starch; and (3) Dietary fiber. Only sugar and starch is digested, as the human body lacks the digestive enzymes to break down (metabolize) dietary fiber in the intestinal tract.
Carbs in Natural Foods
Sugar-carbs are found in a range of natural food, including milk (containing lactose, or milk sugar), fruits (containing fructose, or fruit sugar) and sugar beet (containing sucrose).
Starch-carbs are found in all cereal grains, as well as roots and tubers. Starchy foods include: bread, pasta, rice, noodles, couscous, tapioca, potatoes, sweet potatoes and yams.
Dietary fiber carbohydrates (soluble and insoluble fiber) are found in most plant foods, like fruits and vegetables, legumes and whole grain cereals.
Foods Contain Different Types of Carbs
Many foods contain a mixture of different types of carbohydrate. For example, many whole grain cereals and beans contain both starch and fiber (soluble and insoluble).
Digestible or Net Carbs
With the advent of low carb diets and carb-counting, it is common to see the phrase "Net Carbs" or "Digestible Carbs." In simple terms, this refers to the total amount of carbs in a particular food that can be absorbed and digested in the intestinal tract. It therefore excludes dietary fiber as this cannot be digested. In simple terms, the easiest way to calculate "net carbs" in a food, is to subtract its content of dietary fiber from it's total carb content.
Glycemic Response to Carb Foods:
To see how rapidly carb-rich foods raise blood glucose levels--> Click http://www.carbs-information.com/gi-values-carbohydrates.htm for GI Values for Carbohydrates'.
Note:
Excellent info on Glycemic Index and Glycemic Load click http://www.alsearsmd.com/pdf/Glycemic_Index.pdf
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.
Source and Refs:
http://www.carbs-information.com/carbs-in-food.htm
http://www.carbs-information.com/carbohydrates.htm
http://www.lowcarbohydratediets.info/low-carbohydrate-food-lists/
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