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.