Absorption of Carbohydrate

Introduction

Carbohydrates provide energy for the body. One of the key nutrients in a person's diet is carbohydrates. They give your cells energy, nourish your brain and neurological system, and maintain your body lean and fit.

Carbohydrates are found in a wide variety of foods, including pasta, bread, rice, sugar, fruit, potatoes, and vegetables, as well as cakes, candies, and soft drinks. This tutorial explores the many types of carbohydrates and how they work in the body, as well as the process of how they are absorbed.

Carbohydrates and its Types

The term "carbohydrates" refers to all different types of sugar and starch, however, not all types of carbohydrates are the same. The word "carbohydrate" is a synonym for the Greek word "saccharide," which implies sugar.

The three forms of carbohydrates are as follows −

• starches

• sugars

• fibre

Classification of a Carbohydrate

Carbohydrates are essentially hydrated carbons. "Carbo" refers to carbon, whereas "hydrate" refers to water. Glucose is the most common carbohydrate in the human body.

Fast-Releasing Carbohydrates

Fast-releasing carbohydrates are more commonly referred to as "sugars." Monosaccharides and disaccharides are two categories of fast-releasing carbohydrates.

Slow-Releasing Carbohydrates

Polysaccharides are a type of slow-releasing carbohydrate. Starches and fibres are the two main categories of polysaccharides.

Digestion and Absorption of Carbohydrates

The taste bud cells in our mouths include protein receptors that allow us to recognize sweetness, one of the five basic flavors of food and drink. Sweetness is stimulated by quickly released carbohydrates. The sweetness of the various forms of carbohydrates varies; some are significantly sweeter than others. In terms of sweetness, fructose ranks first among naturally occurring sugars.

Step 1: Mouth to the Stomach

The mouth is where carbohydrates are first mechanically and chemically broken down. Mastication, another term for chewing, breaks down of foods high in carbohydrates into ever-tinier pieces.

Saliva, produced by the salivary glands in the mouth cavity, coats the food particles. Salivary amylase, the enzyme found in saliva, dissociates the bonds that hold starches and converts amylose and amylopectin into dextrins and maltose. Starches are only partially broken down in the mouth - about 5%.

Since the amylase enzyme cannot work in the stomach's acidic environment, no additional chemical breakdown happens when carbohydrates reach the stomach. However, the mechanical breakdown continues as the stomach's powerful peristaltic contractions blend the carbohydrates into a more homogenous composition.

Step 2: Stomach to Small Intestine

The pancreas releases pancreatic juice and pancreatic amylase enzyme, which is present in this juice restarts the breakdown of dextrins into carbohydrate chains.

Sucrase, maltase, and lactase, collectively known as disaccharides, are three enzymes released by the intestinal cells lining the villi.

• Sucrase converts sucrose into molecules of glucose and fructose

• Lactase dissociates galactose from glucose

• Maltase dissociates the two glucose units in maltose

After being chemically reduced to single sugar molecules, carbohydrates are then transported inside intestinal cells.

Step 3: Moving to the Blood Stream

The small intestine transports monosaccharides and other nutrients into the blood so that they can be delivered to the rest of the body.

The liver is the first organ to receive glucose, fructose, and galactose. It absorbs them, breaks down fructose into even smaller carbon-containing units, transforms galactose to glucose, and either stores the glucose as glycogen or excretes it back into the blood. Hormones regulate the amount of glucose the liver exports to the blood.

Step 4: Leftover Carbohydrates: The Large Intestine

All carbohydrates are effectively digested and absorbed by the body, except dietary fiber and resistant starches (fatty acids and certain gases are produced as bacteria break down these slowly released carbs). These fatty acids are either used to generate energy, excreted, or absorbed into the colon.

Functions of Carbohydrates in the Body

In the human body, carbohydrates serve three main purposes.

Energy Production

Carbohydrates' main function is to give the body's cells energy. As an energy source, most cells favor glucose above other substances like fatty acids. Glucose is the only source of energy that red blood cells can use and even the brain relies only on glucose to generate energy and operate.

Energy Storage

Glucose that is in excess of what the body needs to function is stored as glycogen in the body. At any given time, the body contains roughly 4,000 kilocalories worth of glycogen—3,000 of which are stored in muscle tissue and 1,000 in the liver.

Building Macromolecules

Although the majority of ingested glucose is turned into energy, part of it is transformed into ribose and deoxyribose, which are crucial components of significant macromolecules like RNA, DNA, and ATP.

Health Benefits of Carbohydrates In The Diet

Eating slow-releasing carbohydrates is good for your health than fast-releasing ones, which can be harmful if consumed in excess. The positive effects of whole grains on health are due in large part to their excellent dietary sources of fibre, vitamins, minerals, and healthy fats.

Is there a precise daily intake limit for carbohydrates? Yes, 130 grams per day is the Recommended Dietary Allowance (RDA) for adults and children. This is the typical bare minimum that the brain needs to work effectively.

Dietary Sources of Carbohydrates

All five dietary groups—grains, fruits, vegetables, meats, beans, and dairy products—contain carbohydrates. Fruits, fruit juices, and dairy products are the main sources of fast-releasing carbohydrates, whereas starchy vegetables, legumes, and whole grains are the main sources of slow-releasing carbohydrates.

Factors that Affect Absorption of Carbohydrates

The food matrix and other foods taken at the same time are a couple of the variables that determine how quickly and effectively carbohydrates are digested and absorbed.

The Glycemic Index (GI) is a scale that categorizes foods rich in carbohydrates as "high GI," "mid GI," and "low GI" based on how quickly these foods are broken down and absorbed, as well as how quickly their consumption raises blood sugar levels.

Foods with a high GI are digested more quickly and result in a greater rise in blood glucose levels. Foods with a low GI digest more gradually and do not increase blood sugar levels as much or as rapidly.

The table below lists some instances of elements that influence how quickly carbohydrates are absorbed.

Factors that Affect Carbohydrate Absorption	Examples
COOKING Meals with a lower GI digest more slowly than foods with a higher GI because they have been less cooked or processed.	Slow-cooked oats or brown rice, have a lower GI than foods that are more processed, like instant oats or instant rice. Pasta that is prepared "al dente" has a lower GI.
FIBER Foods containing carbohydrates take longer to digest because of fiber content. High fiber meals often have a lower GI.	Low-fiber meals like white bread and rice cereal have a higher GI than high-fiber foods like whole grain breads, oats, beans, and lentils.
FAT AND PROTEIN Consuming fat or protein with carbohydrates slows down digestion and lowers the GI of the carbohydrates	Snacks with carbohydrates and protein or fat have a lower GI. For example − peanut butter on crackers has a lower GI than plain crackers
ACIDS IN FOODS Acids in food prolong the time it takes the stomach to empty after eating. The GI of carbohydrates is reduced by acids	Foods with vinegar, lemon juice, or citrus fruit added have a low GI.

FAQs

Qns 1. What slows the absorption of carbohydrates?

Ans.Protein and fats slow down the digestion of carbohydrates and delay their absorption into the blood.

Qns 2. What is the primary location for the absorption of carbohydrates?

Ans.The mouth and small intestine are the primary sites of carbohydrate digestion.

Qns 3. Why does the process of carbohydrate absoprtion temporarily stop in the stomach?

Ans.Because of the high acidity, salivary amylase is rendered inactive, which temporarily stops stomach digestion of carbohydrates.

Qns 4. What are the byproducts of carbohydrate absorption and digestion?

Ans.Glucose, fructose, and galactose are the byproducts of carbohydrate breakdown