Carbohydrates and Their Impact on Diet

Carbohydrates Overview

• Definition: Nutritional category for sugars and molecules that the body breaks down into sugars.
• Types:
  • Simple Carbohydrates: Monosaccharides (e.g., glucose, fructose, galactose).
  • Disaccharides: Two simple sugars linked (e.g., lactose, maltose, sucrose).
  • Complex Carbohydrates:
    • Oligosaccharides: 3-10 linked sugars.
    • Polysaccharides: More than 10 linked sugars.

Digestion of Carbohydrates

• Breakdown: Complex carbohydrates are broken down into monosaccharides for energy.
• Blood Sugar Response: Eating carbohydrate-rich foods raises blood sugar levels, normally about a teaspoon.

Starch vs. Fiber

• Both are polysaccharides derived from plants but differ in structure and digestion.
  • Starch:
    • Composed of glucose with alpha linkages, easily digested.
    • Found in foods like crackers and white bread, leading to rapid glucose release.
  • Fiber:
    • Composed of monosaccharides with beta bonds, indigestible by the body.
    • Slows glucose release and provides health benefits.

Glycemic Index (GI)

• Definition: Measures how much a food raises blood sugar levels.
• High GI Foods:
  • Soda and white bread are similar due to rapid glucose release.
  • Foods high in starch have a high GI.
• Low GI Foods:
  • High in fiber (e.g., vegetables, fruits, whole grains), which slow down glucose release.
  • Proteins like eggs, cheese, and meats have the lowest GI.

Role of Insulin in Blood Sugar Management

• Insulin: Hormone that helps manage blood sugar levels.
  • Secreted by the pancreas when blood sugar rises, allowing glucose to enter muscle and fat cells.
  • Initiates conversion of sugar to energy.
• Insulin Sensitivity:
  • Higher sensitivity means better glucose uptake with less insulin.
  • Insulin resistance occurs when cells become less responsive, leading to higher blood sugar and insulin levels.

Risks of High Carbohydrate Diets

• Chronic high carbohydrate consumption can lead to insulin resistance.
• Metabolic Syndrome:
  • Symptoms include high blood sugar, increased waist circumference, high blood pressure.
  • Increases risk for cardiovascular disease and type 2 diabetes.
  • Prevalence is rising (32% of US population affected).

Dietary Recommendations

• Sugar Management: Regardless of taste, excessive carbohydrate intake can be problematic.
• Foods to Limit or Avoid:
  • Pasta, sushi rolls, pita, burritos, donuts, burgers, sandwiches.