CARBOHYDRATES-2022

Carbohydrates Overview

  • Author: Javier Duldulao

  • Date: February 14, 2022

Facts About Carbohydrates

  • Carbohydrates (CHO) are organic compounds composed of carbon, hydrogen, and oxygen.

  • The term "carbohydrate" originates from the German term "Kohlenhydrate."

History of Carbohydrates

  • The original definition of carbohydrates was misleading; for example, compounds like acetic acid and lactic acid were inaccurately included.

  • The term was coined by Karl Schmidt.

  • In biochemistry, carbohydrates are referred to as "saccharides" derived from the Latin word "saccharum," meaning sugar.

  • Justus von Liebig, a German chemist, recognized that energy for the body comes from the oxidation of carbohydrates and fats rather than just carbon and hydrogen.

  • Claude Silbert Hudson is known as the father of carbohydrate chemistry and established "Hudson's rules" for optical rotation of sugars.

Definition of Carbohydrates

  • Common names include sugars, starches, saccharides, and polysaccharides.

  • The term means "hydrate of carbon," with the general formula: Cn(H2O)n. Example: Glucose = C6(H2O)6 or C6H12O6.

  • They are classified chemically as polyhydroxy aldehydes or ketones, their derivatives, or polymers.

  • Carbohydrates are organic biomolecules found abundantly in nature.

Occurrence of Carbohydrates

  • Present in plant and animal cells.

  • Predominantly biosynthesized by plants through photosynthesis (converting CO2, H2O, and solar energy into glucose).

  • The process involves chlorophyll, a green pigment, facilitating glucose conversion.

Classification of Carbohydrates

  • Types:

  • Monosaccharides: Smallest form, cannot be hydrolyzed further; general formula: CnH2nOn.

  • Disaccharides: Comprised of two monosaccharides; examples are sucrose, lactose, and maltose.

  • Polysaccharides: Large number of monosaccharide units; oligosaccharides have 3-6 units, polysaccharides have more than 6.

Detailed Types of Carbohydrates

  • Monosaccharides:

  • Simplest form: Examples include glucose, fructose, and galactose.

  • Glucose is the most important, with the formula C6H12O6.

  • Disaccharides:

  • Composed of two monosaccharides.

  • Common types include:

    • Sucrose: (Glucose + Fructose)

    • Lactose: (Glucose + Galactose)

    • Maltose: (Glucose + Glucose)

  • Classified as reducing (lactose, maltose) or non-reducing (sucrose).

  • Polysaccharides:

    • Generally have the formula (C6H10O5)n.

    • Include starch, glycogen, and cellulose (plant fiber).

    • Homopolysaccharides: Composed of the same type of monosaccharide.

    • Heteropolysaccharides: Composed of different monosaccharides.

Biomedical Importance of Carbohydrates

  • Provide energy; calorific value is approximately 4 Cal/gm.

  • Stored in reserve forms such as glycogen and fat for emergencies.

  • Non-digestible carbohydrates like cellulose function as dietary fiber, preventing constipation and aiding in weight management.

  • Dietary reference: Adults should consume 20-25 gm/day; children 5-10 gm/day.

Therapeutic and Diagnostic Uses

  • Carbohydrates in Medicine:

  • Cardiac glycosides like digoxin treat cardiac insufficiency.

  • Mannitol used as a diuretic in acute renal failure.

  • Lactulose alleviates hyperammonaemia.

  • Inulin is used in the Inulin Clearance Test to measure renal function.

Dietary Guidelines

  • Recommended intake for carbohydrates: 55% of total caloric intake.

  • No more than 8 tsp of added sugars per day is suggested based on a 2,000 calorie diet.

  • Preference for carbohydrates from whole foods (fruits, vegetables) over refined sugars.

Sugar Substitutes

  • Include both natural and artificial sweeteners.

  • Importance of understanding caloric values and potential health implications of use.

Conclusion

  • Carbohydrates are essential not only as an energy source but also for their role in overall health and in clinical applications.