CARBOHYDRATES AND IT’S CLASSIFICATION

We need many essential nutrients for the optimum functioning of our body. Proteins, for example, help repair and grow body tissues. Fats act as energy reserves and provide warmth and insulation to the body. Carbs are also one of the essential macronutrients which perform various body functions, and we should take the recommended amounts in our diet to stay healthy.

However, many people know little about carbohydrates and don’t know how much carbs they should put on their plates. This mindless eating and confusion about carbs is quite common in Americans. According to an Atkins^TM Carb Index Survey, six out of ten Americans do not know how much carbohydrates they should eat daily. At the same time, most of them are unaware of the differences between healthy and unhealthy carbs and related food choices (1).

As both overconsumption and under-consumption of carbohydrates are detrimental to health and cause various health problems, it is essential to know how to balance your diet and why carbs are essential for your body. This article will help you understand everything about carbohydrates.

WHAT ARE CARBOHYDRATES?

Carbohydrates are one of the essential macronutrients the human body requires to generate energy. They are mainly used to produce glucose, the primary energy source utilized by the cells for performing various body functions. The extra glucose is stored in the body for future use. Carbs are generally acquired from plant foods, dairy products, vegetables, grains, etc.

CLASSIFICATION OF CARBOHYDRATES

There are several classifications of carbohydrates. Based on the number of sugar units, carbohydrates are mainly classifiedas (2):

• Monosaccharides: ‘Mono’ means one, which depicts that these are simple sugars as they have only one sugar unit and can not be broken or hydrolyzed into smaller units any further—for example, glucose, mannose, ribose, etc.
• Disaccharides: ‘Di’ means two, and so these contain two units of carbohydrates. Therefore they can be broken down into two monosaccharide units upon hydrolysis. For example, sucrose (glucose and fructose), lactose (glucose and galactose), and maltose (two units of glucose).
• Oligosaccharides: ‘Oligo’ means few. They contain 3 to 10 units of the same or different monosaccharides that can be yielded on hydrolysis—for example, raffinose (three saccharide units of galactose, glucose, and fructose).
• Polysaccharides: ‘Poly’ means many. These carbohydrates yield more than ten units of monosaccharides upon digestion—for example, cellulose.

These structural differences render specific properties and functions to different types of carbohydrates. For example, simple carbohydrates are sweet, unlike polysaccharides, so their presence makes the food sweeter.  Fruits are sweet because they are loaded with fructose (a monosaccharide). The same applies to milk, in which galactose is a sweetening agent. 

Polysaccharides, on the other hand, have a complex structure and are made up of many units of monosaccharides. They can provide structural stability and storage units for subsequent energy release after hydrolysis.

METABOLISM OF CARBOHYDRATES IN THE BODY

The body’s digestive system helps break down complex carbohydrates into simple molecules, which the cells store or utilise for energy production. The metabolism of different carbohydrate types in the body differs from each other. Simple sugars are absorbed as such; complex sugars are broken down into simple sugars before absorption; while fibres are not digested, they play an essential role in the health of the digestive system.

The digestion and absorption of carbohydrates are discussed below;

DIGESTION

Each part of the digestive system plays an integral role in the digestion of carbohydrates (3).

• The digestion process starts as soon as we take a bite of our food into the mouth. The salivary glands release saliva which provides lubrication. A digestive enzyme, amylase, present in the saliva starts the process of breakdown of complex sugars into simpler units.

(Fun Fact: Only 5% of the breakdown of complex carbohydrates occurs in the mouth; as a result, maltose is produced, which enhances the sweetness.)

• The swallowed food, whose digestion has already started in the mouth, gets into the stomach, where an acidic environment kills the bacteria in the ingested food. Although no chemical digestion of carbohydrates occurs in the stomach, the organ helps in the mechanical breakdown of the food into smaller pieces. It makes a uniform mixture which is then delivered to the next part of the digestive tract.
• The major breakdown and digestion of carbohydrates occur in the small intestine (4). Bile from the gall bladder and the enzymes in the pancreatic juice and intestinal secretions play a significant part and complete the breakdown of carbohydrates into simple sugars. These simple units of carbohydrates, or monosaccharides, are absorbed by the gut and distributed throughout the body.
• Fibres and some complex resistant carbohydrates that do not get digested or absorbed into the body eventually form the bulk of stools and are excreted out of the body.

ABSORPTION

Several transport proteins are present in the cells of the small intestine, which pick up the digested carbohydrates from the gut lumen and transfer them into the bloodstream (4).

The blood then delivers them to different organs of the body. The first organ to receive these sugar units is the liver. The liver either converts them into glucose or stores them in the form of glycogen.

Hormones, like insulin and glucagon secreted from the pancreas, control the amount of glucose and glycogen stored by the liver or their utilization for energy production.

FUNCTION OF CARBOHYDRATES

Carbohydrates are essential macronutrients and perform various functions in the human body. These include (5):

• Energy Production: It is the most important function of carbohydrates as they are the body’s primary energy source. Carbohydrates’ breakdown generates glucose molecules which are broken down via glycolysis to release ATP. This ATP is the body’s ultimate energy currency which the cells use to perform their respective functions. Some cells and organs depend mainly on glucose for energy, such as red blood cells and the brain.
• Energy Storage: The excess glucose is stored as glycogen for later use. The two main storage sites of glycogen are the muscles and the liver. The body uses these energy stores in a time of need.
• Synthesis of Macromolecules: Some of the absorbed glucose is used to make macromolecules such as ribose and deoxyribose, which are the key component of RNA, DNA, ATP, NADPH, etc. These macromolecular are structural components of every cell in the body and perform essential functions.

It must be noted that when glucose reserves are low, the body starts utilizing proteins and lipids for energy production. If proteins and fats get used up for energy purposes instead of performing their function, this can lead to disturbance causing several detrimental effects on the body. Hence, carbohydrates must be taken in the recommended amounts to meet the body’s energy requirements.

FOODS RICH IN CARBOHYDRATES

Some common foods that contain lots of carbohydrates include (6):

•  Grains such as rice, cereals, wheat, etc.
• Milk and milk products, like yoghurt
• Fruits, e.g., apple, banana, mango, orange
• Vegetables like potatoes, corn, etc.
• Legumes, lentils, and peas – etc

However, other food sources also contain carbohydrates, but they are in low amounts—for example, poultry, fish, cheese, oils, nuts, etc.

GOOD CARBS AND BAD CARBS

Some nutritionists classify carbohydrates into “good” and “bad” categories for people to understand the nutritional value of these carbohydrates.

Good carbs are carbohydrates that do not raise blood sugar levels quickly, like whole grains, rice, legumes, etc. Usually, complex carbohydrates and fibres are considered good carbs because they are not easily digested and create a sense of satiety and fullness. So, along with providing health benefits to the digestive system, they also prevent overeating and obesity.

Bad carbs, conversely, are carbohydrates that are easily digested and quickly raise the blood sugar level, causing a spike. These carbs also make you feel hungry sooner, resulting in overeating. Foods containing bad carbs include sweets, cakes, soft drinks, etc.

Therefore, experts recommend including foods rich in good carbs in our diet.

HEALTH BENEFITS OF EATING CARBOHYDRATES

Carbohydrates have multiple health benefits for the body. As they are the primary energy source, they allow the organs and tissues to function properly, leading to a healthy body. These health benefits of carbohydrates are listed below (7):

• Make us feel energetic: With an adequate supply of energy in the body, the person feels energetic all day, performing all his functions properly without feeling weak and tired.
• Good for Mood: Intake of carbohydrates releases a happy hormone called serotonin which gives a sense of satiety and uplifts the mood.
• Better Sleep: Good carbohydrates at bedtime or dinner help you have a good night’s sleep.
• Good Digestive Health: Fibres are mostly plant-based food that forms the bulk of stool. However, they are essential for the proper functioning of the bowels.
• Memory and Skin Benefits: Energy-rich carbohydrates and fibers improve memory and provide healthy skin.
• Prevention Risk Of Diseases And Cancer: Healthy fibrous foods help prevent certain diseases like obesity, diabetes, and cardiovascular disorders. Moreover, plant fibres, such as whole grains and vegetables, decrease the risk of certain malignancies, like stomach and colon cancer.

DISADVANTAGES OF TAKING TOO MANY CARBOHYDRATES

While carbohydrates have numerous health benefits, they can be unhealthy for the human body if they are taken in excessive amounts or consumed with the wrong type of carbohydrates. These possible risks and disadvantages associated with carbohydrates include (8, 9);

• Weight Gain and Obesity: Taking too many carbs and calories can lead to weight gain, causing obesity, which is itself a risk factor for many diseases.
• Increased Blood Sugar Levels and Diabetes: Increased uptake of carbohydrates and eating sugary foods can lead to spikes in blood sugar levels. The persistent rise in blood sugar levels can make you pre-diabetic or even diabetic. Diabetes can worsen over time if poorly controlled and can cause acute emergencies and many chronic health disorders.
• Cavities and Dental Problems: Carbohydrates containing too much starch, such as pasta, bread, fries, and sweets, can cause cavities and many other dental problems. Bacteria feed on these simple sugars = and produce acids that can lead to tooth decay.
• Fatigue and Slow Brain: High intake of carbohydrates can lead to feelings of tiredness and a sluggish brain. It can also disturb sleep patterns, making a person feel exhausted and low mood.
• Acne: Foods rich in carbohydrates and added sugars were found to have caused acne outbreaks and dull skin.

LOW-CARB DIET FOR WEIGHT LOSS

Low carb diet can help you lose weight and reduce the risk of diabetes and obesity. However, it must be done under supervision, as a low-carb diet can also lead to constipation, muscle cramps, headache, etc. A low-carb diet generally contains 20-55g of carbohydrates every day. It focuses on protein-rich foods with non-starchy vegetables. Different regimens and diet plans can be customized according to one’s needs.

INTERESTING STATS ABOUT CARBOHYDRATES CONSUMPTION IN THE USA

Americans should be extra vigilant about the carbs in their diet because of the increasing obesity, diabetes, and other health problems related to unhealthy eating. The following stats are an accurate depiction of it.

• America ranks number 1 in the consumption of sugars (10). It has been found that sugary drinks are the most common source of sugar consumption by Americans. Sugar consumption is directly linked to increased risk of weight gain, obesity, cardiovascular diseases, tooth decay, and many more. According to an estimate, every one in ten Americans has diabetes.
• Large populations in America do not eat enough fibres in their food. Only 5% of Americans eat the recommended daily intake of fibre, 25g for women and 38g for men. People are generally unaware of the health benefits of fibres, which include slowing down glucose absorption, preventing spikes of blood glucose after a meal, lowering blood cholesterol levels, etc. (11).

CONCLUSION

Carbohydrates are essential macronutrients that provide energy to the body. They perform various bodily functions, including energy production, storage, building macromolecules, and sparing proteins and fats. The recommended daily intake of carbs is around 275g per day, making up 45% to 65% of the daily calories requirement.

Good carbs can lead to an energetic body, good sleep, mood elevation, memory enhancement, and more. However, taking too many carbohydrates or taking the wrong type of carbohydrates can lead to increased risks of many health problems. Therefore, we need to monitor the amount and type of carbs in our diet.

References:

1. Atkins Nutritionals Inc. Atkins survey finds Americans are confused about carbohydrates [Internet]. 2018 [cited 2023 Jul 26]. Available from: https://www.prnewswire.com/news-releases/atkins-survey-finds-americans-are-confused-about-carbohydrates-150560005.html
2.  Singh A. Structure, classification, and functions of carbohydrates [Internet]. Conduct Science. 2021 [cited 2023 Jul 24]. Available from: https://conductscience.com/structure-classification-and-functions-of-carbohydrates/
3. Marcin A. Carbohydrate digestion: Absorption, enzymes, process, and more [Internet]. Healthline. 2018 [cited 2023 Jul 24]. Available from: https://www.healthline.com/health/carbohydrate-digestion
4. 3.3: Digestion and Absorption of Carbohydrates [Internet]. Medicine LibreTexts. 2017. Available from: https://med.libretexts.org/Courses/American_Public_University/APUS%3A_An_Introduction_to_Nutrition_(Byerley)/APUS%3A_An_Introduction_to_Nutrition_1st_Edition/03%3A_Carbohydrates/3.03%3A_Digestion_and_Absorption_of_Carbohydrates
5. ‌University of Hawai’i at Mānoa Food Science, Human Nutrition Program. The functions of carbohydrates in the body. In: Human Nutrition [DEPRECATED]. 2017.
6. Carbohydrates. Food and Nutrition [Internet]. 2003 [cited 2023 Jul 24]; Available from: https://medlineplus.gov/carbohydrates.html
7. Firdous H. Carbohydrates benefits, sources and its side effects [Internet]. Lybrate. 2017 [cited 2023 Jul 24]. Available from: https://www.lybrate.com/topic/carbohydrates-benefits-,-sources-and-side-effects
8. L.D EC R. D. The Disadvantages of Carbohydrates [Internet]. Weekand. 2013. Available from: https://www.weekand.com/healthy-living/article/disadvantages-carbohydrates-18008242.php
9. ‌Csatari J. 8 Side Effects of Eating Too Many Carbs [Internet]. Eat This Not That. 2020. Available from: https://www.eatthis.com/side-effects-of-eating-too-many-carbs/
10. Overview [Internet]. Healthy Food America. Available from: https://www.healthyfoodamerica.org/sugartoolkit_overview#:~:text=Consuming%20added%20sugars%20raises%20the
11. ‌Belluz J. Nearly all Americans fail to eat enough of this actual superfood [Internet]. Vox. 2019 [cited 2023 Jul 25]. Available from: https://www.google.com/amp/s/www.vox.com/platform/amp/2019/3/20/18214505/fiber-diet-weight-loss
12. ‌