Nutrition Basics: Carbohydrates Practice Flashcards

Carbohydrates are organic compounds with a ratio of $1$ carbon atom to $2$ hydrogen atoms to $1$ oxygen atom.
Fast-Releasing Carbohydrates (Simple Sugars):
- Monosaccharides: Simplest units (Glucose, Fructose, Galactose).
- Disaccharides: Two units linked; must contain at least one glucose (Lactose, Maltose, Sucrose).
Slow-Releasing Carbohydrates (Complex Carbohydrates):
- Polysaccharides: Long chains (branched or unbranched) including Starches and Fibers.
- Subgroups include amylose, amylopectin, glycogen, dietary fiber, and functional fiber.

Mouth: Chewing provides mechanical digestion; salivary amylase begins chemical breakdown by breaking glycosidic bonds.
Stomach: Acidic conditions stop salivary amylase; no further chemical breakdown occurs.
Small Intestine: Pancreatic amylase and disaccharidases finish breakdown into monosaccharides.
Absorption: Transport proteins move monosaccharides into the bloodstream; the liver is the first organ to receive them.
Large Intestine: Bacteria digest some indigestible carbohydrates.

Hormonal Control: Insulin and glucagon (released by the pancreas) regulate blood glucose.
Glycemic Index (GI): Measures the effects of foods on blood-glucose levels.
Glycemic Load (GL): Calculated as $\frac{(\text{GI} \times \text{Available Carbohydrate content})}{100}$ .
- High GL: $\geq 20$ points.
- Medium GL: $11 - 19$ points.
- Low GL: $\leq 10$ points.

Energy Production: Glucose is broken down via glycolysis (ten-step process yielding $2$ ATP) and cellular respiration in the mitochondria.
Energy Storage: Excess glucose is stored as glycogen. The body stores approximately $4,000 \, kcal$ ( $3,000 \, kcal$ in muscle, $1,000 \, kcal$ in the liver).
Building Macromolecules: Glucose is used to synthesize ribose and deoxyribose for RNA, DNA, and ATP, as well as NADPH for oxidative stress protection.
Sparing Protein: Prevents gluconeogenesis (the destruction of muscle tissue to create glucose from noncarbohydrate sources like lactate or amino acids).
Lipid Metabolism: Glucose inhibits the use of lipids for fuel ("fat-sparing" effect) and prevents ketosis (elevation of ketone bodies).

Type 1 Diabetes: Immune system destroys insulin-secreting cells; usually occurs before age $30$ ; requires insulin injections.
Type 2 Diabetes: Metabolic disease of insulin insufficiency or resistance; often gradual onset; managed by low-GI diet and physical activity.
Metabolic Syndrome: A condition characterized by having three or more risk factors for Type 2 diabetes and cardiovascular disease.

Added Sugars: Recommended limits are $\leq 9$ teaspoons/day for men and $\leq 6$ teaspoons/day for women.
Oral Disease: Fermentable sugars (glucose, fructose, maltose) metabolized by bacteria cause cavities.
Whole Grains: Rich in fiber and plant chemicals; reduce risks of obesity, Type 2 diabetes, and cardiovascular disease.
Low-Carbohydrate Diets: Can improve insulin resistance, lower blood pressure, and reduce triglycerides.

Recommended Dietary Allowance (RDA): $130 \, g/day$ (minimum for optimal brain function).
Acceptable Macronutrient Distribution Range (AMDR): $45 \% - 65 \%$ of total calories.
Adequate Intake (AI) for Fiber: $38 \, g$ for men; $25 \, g$ for women (ages $19 - 50$ ).
Fiber Content in Specific Foods:
- Lentils (1 c.): $16.0 \, g$
- Popcorn (homemade 100 g): $10.0 \, g$
- Apple (1 medium): $4.4 \, g$

Sugar-free: < 0.5 \, g sugar per serving.
High fiber: $\geq 20 \%$ of daily value per serving.
Good source of fiber: $10 - 19 \%$ of daily value per serving.
Nutrient-Dense Choices: Prioritize whole-wheat flour, cornmeal, legumes, and whole grains (barley, quinoa, bulgur) while avoiding HFCS and long ingredient lists.