continued from previous article published in march 2019.
Macronutrients : 1. Carbohydrates
Macronutrients are essential for proper body functioning, and the body requires large amounts of them. There are three macronutrients.: carbohydrates, protein and fats,. All macronutrients must be obtained through diet- the body cannot produce macronutrients on its own.
Carbohydrates represent the most important source of energy for the body, and are vital for a varied and balanced diet. The recommended daily amount (RDA) of carbohydrates for a normal healthy adult is 135 grams, Carbohydrate (carbs) intake for most people should be between 45 and 65 percent of total calories. One gram of carbohydrates equals about 4 calories, so a diet of 1,800 calories per day would equal about 202 grams on the low end and 292 grams of carbs on the high end. However, people with diabetes should not eat more than 200 grams of carbs per day,
Simple vs. complex carbohydrates
Carbohydrates are classified as simple or complex. The difference between the two forms is the chemical structure and how quickly the sugar is absorbed and digested. Generally speaking, simple carbs are digested and absorbed more quickly and easily than complex carbohydrates
Simple carbohydrates contain just one or two sugars, such as fructose (found in fruits) and galactose (found in milk products). These single sugars are called monosaccharides. Carbs with two sugars — such as sucrose (table sugar), lactose (from dairy) and maltose (found in beer and some vegetables) — are called disaccharides.
Simple carbs are also present in candy, soda and syrups. However, these foods are made with processed and refined sugars and do not have vitamins, minerals or fiber. They are called “empty calories” and can lead to weight gain.
Complex carbohydrates (polysaccharides) have three or more sugars. They are often referred to as starchy foods and include cereals, lentils (pulses), potatoes, corn etc.,
CLASSIFICATION OF DIETARY CARBOHYDRATES
|Classification of Carbohydrates|
|Monosaccharides||Glucose, fructose, galactose|
|Disaccharides||Sucrose, lactose, maltose|
|Polysaccharides||Amylose, amylopectin, maltodextrins|
|Non-starch polysaccharides (Dietary Fibre)||Cellulose, pectins, hemicelluloses, gums, inulin|
Energy source and storage
Starches and sugars are the main energy-providing carbohydrate sources and supply 4 kilocalories (17 kilojoules) per gram. Monosaccharides and mainly glucose, are absorbed by the small intestine into the bloodstream, where they are then transported to their place of use. Disaccharides are broken down by digestive enzymes into monosaccharides. The body also needs the help of digestive enzymes to break down the long chains of starches into their constituent sugars which are then absorbed into the bloodstream.
Glucose is the most important monosaccharide that is absorbed and the red blood cells, carry it to the different organs for the respective need. The brain needs a steady supply of glucose for its functioning. It is for this reason that glucose in the blood must be constantly maintained at an optimum level. Approximately 130g of glucose are needed per day to cover the energy needs of the brain. Glucose may come directly from dietary carbohydrates, from glycogen stores, or from the conversion of certain amino acids resulting from protein breakdown. Several hormones, including insulin, work rapidly to regulate the flow of glucose to and from the blood to keep it at a steady level.
To be continued……
Article written by:
Dr Manonmani Seenivasan