CHAPTER 3 NOTES

  1. Monosaccharides – The simplest form of carbohydrates, consisting of single sugar molecules (e.g., glucose, fructose, galactose).

  2. Disaccharides – Carbohydrates composed of two monosaccharides bonded together (e.g., sucrose, lactose, maltose).

  3. Polysaccharides – Complex carbohydrates made of long chains of monosaccharides (e.g., starch, glycogen, fiber).

  4. Sucrose – A disaccharide made of glucose and fructose; commonly known as table sugar.

  5. Lactose – A disaccharide made of glucose and galactose; the primary sugar in milk.

  6. Fibers – Indigestible carbohydrates found in plant-based foods that aid digestion and provide health benefits.

  7. Gluconeogenesis – The process of producing glucose from non-carbohydrate sources, such as proteins.

  8. Insulin – A hormone produced by the pancreas that helps lower blood sugar levels by facilitating glucose uptake into cells.

  9. Glucagon – A hormone that raises blood sugar levels by promoting glycogen breakdown in the liver.

  10. Glycogen – A polysaccharide that serves as stored glucose in the liver and muscles.

  11. Soluble fiber – A type of fiber that dissolves in water and helps lower cholesterol and regulate blood sugar (e.g., oats, beans).

  12. Insoluble fiber – A type of fiber that does not dissolve in water and promotes digestive regularity (e.g., whole grains, vegetables).

  13. Nutritive sweeteners – Sweeteners that provide calories, such as sugar and high-fructose corn syrup.

  14. Nonnutritive sweeteners – Artificial or natural sweeteners that provide little or no calories, such as aspartame and stevia.

  15. Glycemic index (GI) – A measure of how quickly a carbohydrate-containing food raises blood glucose levels.

  16. Glycemic load (GL) – A measure that accounts for both the glycemic index and the carbohydrate content of a food serving.

Key Concepts:

  • Main function of carbohydrates – Provide energy for the body, particularly for the brain and muscles.

  • Basic unit of all carbohydrates – Monosaccharides.

  • Differences between carbohydrate types:

    • Monosaccharides: Single sugar units (glucose, fructose, galactose).

    • Disaccharides: Two sugar units (sucrose, lactose, maltose).

    • Polysaccharides: Long chains of sugar units (starch, glycogen, fiber).

  • Purpose of insulin – To regulate blood glucose by promoting glucose uptake in cells.

  • Low carbohydrate intake consequences – Can lead to gluconeogenesis and ketosis.

  • Blood glucose regulation – Managed by insulin (lowers blood sugar) and glucagon (raises blood sugar).

  • White sugar – Sucrose.

  • Principal carbohydrate in milk – Lactose.

  • Fiber digestion – Beneficial gut bacteria help ferment and break down fiber.

  • Glycogen storage – Stored in the liver and muscles as an energy reserve.

  • Soluble vs. Insoluble fiber:

    • Soluble fiber examples – Oats, beans, apples, carrots.

    • Insoluble fiber examples – Whole wheat, brown rice, leafy greens.

  • WHO recommendation for added sugars – Less than 10% of total daily energy intake.

  • Carbohydrate digestion enzymes:

    • Amylase – Breaks down starch into maltose.

    • Maltase – Breaks maltose into glucose.

    • Lactase – Breaks lactose into glucose and galactose.

    • Sucrase – Breaks sucrose into glucose and fructose.

  • Fiber and cholesterol:

    • High-fiber diet – Can lower cholesterol by binding bile acids.

    • Low-fiber diet – May lead to higher cholesterol and heart disease risk.

  • Adequate fiber intake:

    • Women: ~25g/day

    • Men: ~38g/day

    • Fiber-rich foods – Whole grains, fruits, vegetables, legumes.

  • AMDR for carbohydrates – 45-65% of total daily calories.

    • Example calculation: If consuming 2000 kcal/day, carbs should be 900–1300 kcal (225–325g of carbs).

  • Who should monitor glycemic index? – People with diabetes or those managing blood sugar levels.

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