Mis à jour : 3 août 2020
Carbohydrates are a major source of nutrient to provide energy for our bodies, consisting of 45-65% of calories in the standard American diet. Carbohydrates are found in grains, vegetables, fruits, legumes, soda, juice, and desserts, among other sources, and it is more abundant and affordable because of the genetic modification of plants and products that make them easier to grow, as well as more palatable.
We need Energy to move and to perform work. This energy consumed in the form of carbohydrates. Carbohydrates primary starches an easily obtained and readily digested form of energy.
A starch is simply a more complex form of sugar that is broken down by the body into glucose. are from grains and starchy vegetables like potatoes, beans, and legumes. Starches from grains are predominantly flour products, as well as other grains like oats.
Dietary fiber is most often found in many of the same foods as starches, such as whole grains. Fiber can’t be broken down into sugar and is most beneficial because of the indigestible compounds it contains. These are used by bacteria also in the body for multiple benefits. Fiber is very important to proper health.
Simple Definition: Carbohydrate actually covers three separate groups: sugar, starch and fiber. In its simplest form, a carbohydrate is glucose a vital source of energy.
The basic structure of carbohydrates are carbon chains (C), hydrogen (H), and oxygen (O), with two functional groups: a polyhydroxy, or –OH group, and a carbonyl, or C=O group. Carbohydrates are classified depending on number of Sugar units as simple and complex carbohydrates
Functions of carbohydrates
Glucose- they are important for maintaining the functional integrity of the nervous tissue and proper functioning of brain
Protein action- if sufficient amount of carbohydrate are not available in the diet the body will convert protein to glucose in order to supply energy
Fat metabolism- they are essential to maintain normal fat metabolism. Insufficient carbohydrates may lead to the accumulation of acidic intermediate products called Ketone bodies
Synthesis of body substances -They are used in synthesize of non-essential amino acids, glycoproteins and glycolipids. Lactose remains in the intestine longer than other disaccharides and thus increase growth of beneficial bacteria.
Types of dietary carbohydrates
Based on size and chemical composition
We have only one or two units of sugar that is monosaccharide and disaccharides
Types of monosaccharide
Type of disaccharides
They are polysaccharides they are more than two units of sugar also called oligosaccharides
Carbohydrate Digestion and Absorption: The body can only absorb monosaccharides, so oligo- and polysaccharides must be broken down into monosaccharide units during digestion. This digestion happens in the oral cavity (or the mouth), the stomach, and the small intestine, and involves multiple enzymes, some of which are general, and some of which are specific to a certain type of carbohydrate. For example, the enzyme alpha amylase breaks down both oligo- and polysaccharide bonds in the oral cavity, while the enzyme lactase works specifically on the breakdown of the bonds in lactose, an oligosaccharide, in the small intestine.
Starch- this are easy to digest carbohydrates store in plant found in the inner part of the plant foods mainly serials and vegetables
· Fiber- this is the non-digestible protective covering in plants found in the outer part of the food mainly fruits cereals and vegetables
· Muscle glycogen- carbs found in muscle and liver of living human and animals.
Based on the speed of digestion
Hence all fiber rich carbs are categorized as low absorbed carbohydrates and low fiber carbs are categorized as fast absorbed carbohydrates
Implications in the Body: Carbohydrates, once they are broken down into glucose, are the first source the body uses for energy in cells. Blood glucose levels must be tightly regulated within the body. Not enough blood glucose in the body, or hypoglycemia, in the short term can result in excessive hunger, fatigue, lightheadedness, and a lack of mental clarity because the body doesn't have enough fuel for energy. Too much blood glucose, or hyperglycemia, can result in weight gain, and in the long term can result in Type 2 Diabetes, obesity, and heart disease
Sources. Quora.com and Essentials of biochemistry by mushtaq Ahmed.