You may have heard that Carbohydrates are bad for you from friends, families, and even the media. Celebrities in the media and magazines have long advertised low-carb and high-protein or keto diets, but carbohydrates are found all around us. They are located in the foods we commonly eat, including noodles, potatoes, pasta, rice, etc. They can come in many forms, and our bodies process them, so how can they be harmful? The answer is that carbohydrates aren't exactly bad, but some might be better for our bodies than others. In the following, we will explore this idea and address misconceptions commonly associated with simple Carbohydrates.
Figure 1: Examples of carbohydrates. Pixabay.
Simple carbohydrates definition
Simple carbohydrates are carbohydrates made of one or two molecules of sugar.
Carbohydrates are the most common organic compounds that consist of carbon, hydrogen, and oxygen that serve as a source of energy for living organisms.
Organic compounds are essentially chemical compounds that contain carbon bonds. Carbon is essential for life as it quickly forms bonds with other molecules and components, allowing life to occur readily.
The arrangement of carbon to hydrogen and oxygen gives carbohydrates their name.
One carbon atom (\(C\)), two hydrogen atoms (\(H\)), and one oxygen atom (\(O\)) are what make up the foundation of carbohydrates.
You may have noticed that this combination of particles makes it a pairing of Carbon (carbo-) and water (-hydrate). How we differentiate carbohydrates is by the length of these atomic chains. Examining the atomic chain allows us to put carbohydrates into three main groups: Monosaccharides, disaccharides, and polysaccharides. All of these carbohydrates store energy for some time in some form.
Simple carbohydrates function
Carbohydrates are used to store energy. Every ounce of this energy is used by the human body when ingested, as carbohydrates are essential to our nutrition. Besides fueling your body, carbohydrates also assist in making lipids and building essential macromolecules, and their byproducts aid the immune system, reproduction, and energy production.
Macromolecules are large molecules vital to biological processes such as proteins, nucleic acids, and carbohydrates.
Proteins are organic compounds, like carbohydrates, but their main functions include acting as antibodies to protect our immune system, enzymes to speed up chemical reactions, etc.
Nucleic acids are organic compounds such as RNA and DNA. DNA (deoxyribonucleic acid) acts as the genetic information in living organisms.
Carbohydrates provide our bodies with glucose, a simple sugar that can be converted into energy or ATP to power our Cells.
ATP or adenosine phosphate is an organic compound that provides the cell energy for its metabolic processes. Metabolic processes are chemical reactions in Cells, such as Photosynthesis and cellular Respiration.
Cellular Respiration is the process by which we convert glucose, a simple carbohydrate, into ATP.
Types of simple carbohydrates
Monosaccharides are simple sugars, like glucose and fructose, and are considered Monomers or the building blocks of carbohydrates. Many of the foods that are eaten all over the world contain glucose or fructose. These foods include honey, grape juice, jackfruit, soft drinks, dried cranberries, apples, grapes, pears, and raisins.
- Fructose is a simple sugar easily found in the external environment via fruit. Glucose, on the other hand, is usually derived from the digestion of other carbohydrates. Both glucose and fructose have the same chemical formula, but with closer examination, we see that the atoms of glucose and fructose are arranged differently, making them isomers.
- Glucose is one of the most abundantly available simple carbohydrates and is utilized by almost everything on the planet. This simple sugar is created during the Photosynthesis process, after which it is used during the cellular respiration process to give energy.
- Glucose and fructose are isomers. Isomers are compounds that possess the same formula but have a different arrangement of atoms or structures. This difference in form gives glucose and fructose individual properties.
When specifically only two monosaccharides link together, it’s called a disaccharide. The most common disaccharide that many of us use today would be in the form of table sugar or sucrose.
- Table sugar is made up of both glucose and fructose. Another common form of a disaccharide is lactose.
- Lactose is a sugar created by pairing glucose with galactose and can be commonly found in the milk of Mammals.
Both monosaccharides and disaccharides are considered simple carbohydrates because of their less complex structure.
Simple carbohydrates examples
After going over a simple carbohydrate, its function, and its types, we need to go over the examples of simple carbohydrates.
Examples of common monosaccharides:
- Glucose: This simple sugar provides our cells with a significant energy source, and its formula is \(C_6H_{12}O_6\).
- Ribose: This is a five-carbon or pentose sugar crucial for creating ATP and RNA. RNA or ribonucleic acid acts as a messenger for DNA and controls the creation of proteins.
- Deoxyribose: Deoxyribose is a sugar synthesized when ribose's hydroxyl group is replaced with hydrogen. DNA or deoxyribonucleic acid is made of deoxyribose sugar and phosphate groups.
- Mannose: Mannose is a monosaccharide that is a hexose and can naturally occur in some plants like cranberries.
- Fructose: Fructose is a sugar mainly found in fruits and vegetables, an isomer of glucose.
- Glyceraldehyde: Glyceraldehyde is made of three carbon atoms and is one of the sugars we can get from photosynthesis and cellular respiration (the glycolysis step of cellular respiration).
Figure 2: Examples of glucose, fructose, and mannose are shown. Wikimedia.
Examples of common disaccharides:
- Sucrose: Sucrose or table sugar is produced by plants in photosynthesis and consists of fructose and glucose. We commonly use sucrose as a sweetener for desserts, a sugar found in fruits, vegetables, etc.
- Lactose: Lactose consists of glucose and galactose and is a sugar found in milk. Bacteria also use lactose to synthesize yogurt and cheese.
- Maltose: Maltose or malt sugar is produced through the breakdown of starch and is usually used to make beer.
- Trehalose: Disaccharide sugar is made of two glucose Monomers, found in many organisms but not Mammals, to aid cells against desiccation or drying out.
Figure 3: Sucrose illustrated. Wikimedia.
Simple carbohydrates vs. complex carbohydrates
Polysaccharides and oligosaccharides are considered complex carbohydrates. The molecules are formed when many groups of simple sugars are chained together.
Polysaccharides consist of multiple monosaccharides or more complicated structures, making them complex carbohydrates.
Examples of polysaccharides would be starch, glycogen, cellulose, and chitin.
Oligosaccharides are carbohydrates usually consisting of three to ten monosaccharides, while polysaccharides are, on average, longer.
Examples of oligosaccharides include raffinose and oligofructose.
On the other hand, simple carbohydrates consist of one sugar or monosaccharide and two sugars or disaccharides. Simple carbohydrates are used for energy faster by the body than complex carbohydrates because they are shorter and less complex. This means that simple carbohydrates usually lead to a quicker rise in Blood sugar and pancreatic insulin secretion, sometimes resulting in harmful health effects.
Just because carbohydrates are simple or complex does not mean they will always be healthy or unhealthy. To obtain the whole story, we need to consider the glycemic index.
The glycemic index sorts carbohydrates based on how fast and how much it raises Blood sugar levels on a scale of 0 to 100. The closer to 100, the food scores on the index are quickly broken down, resulting in a fast rise in Blood sugar levels compared to foods that score closer to 0.
Examples of foods with high glycemic indexes include soda, fast food, potatoes, chips, etc. In contrast, foods with lower glycemic indexes include fruits, eggs, etc. A glycemic index of 56-69 makes it a medium-level food.
Consuming lots of foods with high glycemic index results in a higher risk of type 2 diabetes, heart disease, and colon cancer; in contrast, foods with low glycemic indexes have demonstrated can help regulate type 2 diabetes, lead to weight loss, and lead to some anti-inflammatory benefits.
Remember that any carbohydrate's glycemic index can be affected by processing, fiber amount, ripeness, acid and fat content, and physical form.
- Processed foods tend to have higher glycemic indexes because you can digest them more easily.
For example, fruit juice has a higher glycemic index when compared to fruits.
- High-fiber foods have a lower glycemic index than low-fiber foods.
- Un-ripened fruit and vegetables have a lower glycemic index than riper fruits and vegetables.
- The physical form of whole grains has a lower glycemic index when compared to processed grains such as whole-grain bread.
- Consuming carbohydrates with fat, acids, and proteins makes digestion slower and lowers the glycemic index.
Overall, simple carbohydrates are broken down or digested rapidly compared to complex carbohydrates causing changes in blood sugar and resulting in us getting hungry sooner. This can result in diabetes and high blood pressure.
Examples of some of the essential complex carbohydrates are:
- Cellulose: The most abundant biopolymer in the world, comprising glucose bonds that can form into dense fibers and compose the cell walls of plants and vegetables. It can be found in wood and cotton. Biopolymers are substances produced by living organisms' cells.
- Starch: The main form of energy storage for plants such as potatoes that are made of numerous glucose units combined. Starch exists in two structural forms: amylose is straight, and amylopectin is branched.
- Glycogen: Glycogen is the primary energy reserve of animals, lodged in bodily tissues and, to a lesser extent, in the liver. It can be broken down to glucose by hydrolysis in situations of energetic necessity and serves as a way to store energy for animals, fungi, and bacteria.
Chitin: Chitin is a structural polysaccharide that's rich in nitrogen and present in the structure of fungi and exoskeletons of arthropods.
It is the most abundant natural polymer in the world after cellulose.
Peptidoglycan: Also known as murein, it is a resistant copolymer that makes up the cell structure in numerous bacteria. Copolymers consist of more than one type of monomer in their chains.
Figure 4: Amylose structure illustrated. Wikimedia.
Figure 5: Amylopectin illustrated. Wikimedia.
Simple Carbohydrates - Key takeaways
- Simple carbohydrates are carbohydrates made of one or two molecules of sugar.
- Carbohydrates are the most common organic compounds that consist of carbon, hydrogen, and oxygen that serve as a source of energy for living organisms.
- Organic compounds are essentially chemical compounds that contain carbon bonds. Carbon is essential for life as it quickly forms bonds with other molecules and components, allowing life to occur readily.
- Polysaccharides and oligosaccharides are considered complex carbohydrates. The molecules are formed when many groups of simple sugars are chained together.
- Polysaccharides consist of multiple monosaccharides or more complicated structures, making them complex carbohydrates. Examples of polysaccharides would be starch, glycogen, cellulose, and chitin.
References
- Julie E. Holesh Sanah Aslam and Andrew Martin, Physiology Carbohydrates, 2022.
- Harvard T.H. Chan, Carbohydrates: quality matters, 2022.
- Harvard T.H. Chan, Carbohydrates and Blood Sugar, 2022.
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