In today’s world everyone knows about carbohydrates but one doesn't know the right amount and the type of carbs to consume. It is due to this misconception that people think carbohydrate is the main culprit for the increasing weight or obesity. So their first step is to limit the consumption of carbs but this is not actually true. People still believe in the half knowledge perceived from the surrounding. Moreover, half of the world’s population derives their energy from carbohydrates.
Carbohydrates are one of the major macronutrients in our daily diet while proteins and fats being the other. Carbs are ubiquitously present around us in various forms. When ingested, carbs proffer energy to our cells as it is the main source of energy. Moreover, it is the primary fuel for our working muscles. Glucose is considered as the most nutritional significant because almost all the carbs ultimately break down into glucose (i.e. simplest sugar) in our gut. Therefore, some cells of the body likely brain cells and red blood cells wholly rely on glucose for their functioning. In plants, excess glucose molecules are stored in the form of starch whereas in animals skeleton and liver are the main storage house. Besides being an energy molecule, carbs also play a major role in the structure and functioning of cells, tissue and organs. Hou and Lowary (2009) said that the backbone of inherited molecule i.e. deoxyribonucleic acid is composed of ribose.
What are Carbohydrates?
Sugar molecules are the building blocks of all types of Carbohydrates. Each sugar molecule in turn comprises of three atoms i.e. carbon, hydrogen and oxygen. They are also known as polyhydroxy alcohol containing a potentially active carbonyl group (either aldehyde or keto group) at the terminal end.
Types of Carbohydrates
There are different forms of carbohydrates existing in nature. Therefore, it is important to group these carbohydrates into different categories for the better understanding of their roles. The categorisation of carbohydrates is based on their chemical structure, complexity and glycemic index. They are classified into two broader categories:-
- Simple carbs
- Complex carbs
Simple carbs constitute of sugars such as monosaccharides and disaccharides while complex carbs constitute oligosaccharides and polysaccharides. Further polysaccharides are distinguished into starchy and non-starchy polysaccharides.
As the name suggests, they include a simple unit of carbs. They show a high glycemic response after their ingestion. Glycemic index is referred to as the value assigned to foods on the basis of their ability to release glucose into the bloodstream and spike the blood glucose level. Foods rich in simple carbs have a high glycemic index (GI) as they release sugar immediately after their ingestion and instantly hike the blood glucose level. Long-term compliance with high GI foods such as refined food, sugars, dietary supplements high in calories, sugar beverages may result in nutritional imbalance. This may lead to non-communicable diseases like obesity, hidden malnutrition, type-2 diabetes mellitus, cardiovascular diseases, etc.
Simple carbs have both advantages as well as disadvantages. It is the main ingredient in most of the advertised energy drinks available in the market. It provides a number of benefits to endurance athletes by instantly hiking their blood glucose level and provide fuel to their dynamic muscles. That’s why, endurance athletes (swimmers, cyclist, sprint racers, etc.) consume food high in GI before the competition, in between the competition to maintain their glycogen stores and after the competition high GI foods allow recovery of muscles so as to prevent the breakdown of muscle protein.
The excess non-utilised glucose in our body is converted and accumulated as triacylglycerol in the adipose tissues which in turn, contributes in increasing the body fat and bad cholesterol i.e. LDL (Low-Density Lipoproteins) cholesterol and VLDL (Very Low-Density Lipoprotein) cholesterol. The excess of body fat accumulated in the blood vessels causes narrowing of the vessels and forms a plague that restricts the path of the blood flow. This results in atherosclerosis, peripheral vascular disease and cardiovascular diseases.
A brief description of some of the simple sugars:
Monosaccharides: They cannot be hydrolysed further into simpler units such as glucose, galactose, fructose, mannose and many more. Glucose is the main component of blood sugar and most of the complex carbs are converted into glucose by gut enzymes. Campbell et al. (2010) showed that fructose is the reducing sugar which is predominantly found in different fruits and honey. It is also known as fruit sugar. Fructose can also be derived in the body by the action of sucrase enzyme on sucrose. After fructose, galactose is another reducing sugar which can be obtained from milk.
Disaccharides: They comprise of two sugars which are linked by glycosidic linkage like sucrose (Gucose+Fructose), maltose (Glucose+Glucose), lactose (Glucose+Galactose), etc.
- Lactose: It is the milk sugar present in the body. It gets hydrolyzed by a lactase enzyme which gives glucose and galactose. Venema et al. (2008) indicated that lactase deficiency results in the condition referred to as lactose intolerance where an individual is unable to digest milk and its products. Diarrhoea is one of the symptoms of lactose intolerance.
- Sucrose: It is a non-reducing sugar which is commonly named as table sugar. Table sugar is frequently used for making foods, energy drinks, sugar beverages, etc. Alexander et al. (2004) demonstrated overconsumption of this sugar is correlated with the metabolic syndrome such as diabetes mellitus.
- Maltose: Also known as malt sugar. In human, it is hydrolyzed in the intestine by maltase enzyme to yield 2 molecules of glucose.
When sugar molecules combine to form a long complex chain of carbohydrates. The complex carbs include oligosaccharides and polysaccharides. They are further distinguished as starchy and non-starchy carbohydrates.
Starches for energy
Starchy carbohydrates along with calories also provide vitamins, minerals and fibres. For e.g. whole grains, peas, beans, oatmeal, etc. Complex carbs have a low glycemic response because first, they have to be broken down into simplest unit i.e. glucose before absorption. Due to which they maintain the steady supply of glucose into the bloodstream for a longer time and provide energy for the functioning of the human body. The processing of starchy food is directly correlated to an increase in the glycemic index because it reduces the time and rapidly raises the blood sugar level. Another unique type of starch i.e. resistant starch which remains undigested but fermented by intestinal bacteria yields a number of short-chain fatty acids. It possesses a great benefit for gut health.
It is a complex carbohydrate which remains undigested in the small intestine but gets fermented in the colon by good bacteria. Fibres are also of two types-soluble fibre and insoluble fibre. Soluble fibres, when dissolved in water forms a clear gel while insoluble fibre absorbs water and swell. Soluble fibre is usually recommended during constipation for its ability to extract water and provide relief from the stress condition. In contrast, insoluble fibre is commonly used during diarrhoea as it helps in absorbing water and adds bulk.
Now that we are aware of the positives of carbohydrates before taking the next meal keep in mind the nutritional value of what you eat. It should always be a balance of both simple and complex carbs. Types of simple sugar are monosaccharides, disaccharides, lactose, sucrose, maltose. And complex sugars are starch and fibre.
- Hou, D., & Lowary, T.L.(2009).Recent advances in the synthesis of 2-deoxy-glycosides, Review Article. Carbohydrate Res.344(15):1911-194
- Campbell, B.K., Onions, V., Kendall, N.R., Guo, L., & Scaramuzzi, L.R. (2010). The effect of monosaccharide sugars and pyruvate on the differentiation and metabolism of sheep granulosa cells in vitro. J. Soc.. Reprod. Fertil. 140:541-550
- Alexander, Alfonso., Hernández D, Guillermo., & Lara B, M. (2004). Effects of fish oil on hypertension, plasma lipids, and tumour necrosis factor-alpha in rats with sucrose-induced metabolic syndrome. J. Nutr. Biochem.15 (6): 350–57
- He, T., Venema, K., Priebe, M.G., Welling, G.W., Brummer, R.J., & Vonk, R.J. (2008).The role of colonic metabolism in lactose intolerance. Eur. J. Clin. Invest. 38(8):541-7