Comprehensive Overview of Carbohydrates: Structure, Function, and Nutrition

Comprehensive Overview of Carbohydrates: Structure, Function, and Nutrition

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  CARBOHYDRATES An Introduction toStructure, Function & Nutrition Biology & Nutrition Fundamentals Amit Kumar Singh Assistant Professor Department of Medical Laboratory Science Chandigarh University
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  What Are Carbohydrates? •Carbohydrates are organic molecules made of carbon, hydrogen, and oxygen — usually in a ratio of roughly 1:2:1. • They are the body's primary and most efficient source of energy. • Plants produce carbohydrates through photosynthesis, converting sunlight, water, and carbon dioxide into sugar. • Along with proteins and fats, carbohydrates are one of the three macronutrients. General Formula C (H O) ₙ ₂ ₙ Example: Glucose C H O ₆ ₁₂ ₆ 4 kilocalories of energy per gram Carbohydrates — An Introduction 2
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  Three Classes ofCarbohydrates Classified by the number of sugar units they contain 1 Monosaccharides Single sugar units — the simplest form of carbohydrate. Cannot be broken down further. Glucose · Fructose · Galactose 2 Disaccharides Two monosaccharides joined together by a glycosidic bond. Sucrose · Lactose · Maltose 3 Polysaccharides Long chains of many monosaccharide units, used for storage or structure. Starch · Glycogen · Cellulose Carbohydrates — An Introduction 3
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  Monosaccharides — TheSimple Sugars G Glucose The body's main energy source; circulates in the blood as blood sugar. Fruits, honey, grains F Fructose The sweetest natural sugar; metabolized primarily in the liver. Fruits, honey G Galactose Rarely found alone; combines with glucose to form lactose. Dairy products Carbohydrates — An Introduction 4
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  Disaccharides — TwoSugars Joined Formed when two monosaccharides bond, releasing a water molecule (condensation reaction) G F Sucrose Glucose + Fructose Common table sugar; found in sugar cane and beets. G G Lactose Glucose + Galactose The natural sugar found in milk and dairy products. G G Maltose Glucose + Glucose Formed during starch breakdown; found in malted grains. Carbohydrates — An Introduction 5
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  Polysaccharides — LongChains of Sugar Starch ENERGY STORAGE IN PLANTS The main carbohydrate humans digest for energy; found in grains, potatoes, and legumes. Glycogen ENERGY STORAGE IN ANIMALS Stored in the liver and muscles; rapidly broken down into glucose when energy is needed. Cellulose STRUCTURAL — PLANT FIBER Cannot be digested by humans; forms dietary fiber that supports digestive health. Carbohydrates — An Introduction 6
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  Functions of Carbohydratesin the Body 1 Primary Energy Source Provide 4 kcal per gram; glucose fuels nearly every cell in the body. 2 Energy Storage Excess glucose is stored as glycogen in the liver and muscles for further use. 3 Protein-Sparing Action Adequate carbohydrate intake prevents protein from being broken down for energy. 4 Brain & Nervous System Fuel The brain relies almost exclusively on glucose for normal function. 5 Structural Role Fiber (cellulose) supports digestive health and regulates blood sugar absorption. Carbohydrates — An Introduction 7
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  Food Sources ofCarbohydrates G Grains Rice, wheat, oats, corn F Fruits Apples, bananas, berries V Vegetables Potatoes, carrots, peas L Legumes Beans, lentils, chickpeas D Dairy Milk, yogurt (lactose) A Added Sugars Candy, soda, desserts Carbohydrates — An Introduction 8
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  Digestion & Metabolism Howcarbohydrates travel from plate to cell 1 Mouth Salivary amylase begins breaking starch into shorter chains. 2 Stomach Digestion pauses; acid halts enzyme activity temporarily. 3 Small Intestine Enzymes (maltase, sucrase, lactase) break sugars into monosaccharide's . 4 Absorption Glucose, fructose & galactose pass into the bloodstream. 5 Cells & Liver Glucose is used for energy, stored as glycogen, or converted to fat. → → → → Carbohydrates — An Introduction 9
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  Simple vs. ComplexCarbohydrates Simple Carbs • Quick source of energy • Digested and absorbed rapidly • Can cause fast blood sugar spikes • Found in candy, soda, table sugar Complex Carbs • Longer, steadier energy release • Takes longer to digest • Supports stable blood sugar levels • Found in whole grains, legumes, vegetables Glycemic Index (sample foods) Lentils Oats Brown Rice White Bread 0 10 20 30 40 50 60 70 80 32 55 68 75 Carbohydrates — An Introduction 10
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  Dietary Recommendations 45–65% of dailycalories should come from carbohydrates 25–38 g of dietary fiber recommended per day <10% of daily calories from added sugars • Favor whole, minimally processed sources — whole grains, fruits, vegetables, and legumes — over refined sugars and starches. • Prioritize fiber-rich carbohydrates to support digestion, heart health, and steady blood sugar. • Limit foods and drinks high in added sugar, such as soda, candy, and pastries. Carbohydrates — An Introduction 11
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  Key Takeaways • Carbohydratesare the body's primary energy source, built from carbon, hydrogen, and oxygen. • They come in three forms: monosaccharides, disaccharides, and polysaccharides. • Beyond energy, they support brain function, spare protein, and provide dietary fiber. • Choosing complex, fiber-rich carbohydrates over added sugars supports long-term health. Thank you