Nutrition: Carbohydrates, Starch, Sugars and Fiber

Chapter 4: Carbohydrates, Sugar, Starch, and Fiber

  • Content sourced from Dr. Devries Aboud and Cengage.

Key Concepts for Term Test

  • Microbiome Activities

  • Lymphatic vs. Vascular System

    • Differences in routes and functions.

    • Lymphatic system carries lymph; vascular system carries blood.

  • Functions in the GI Tract

    • Microvilli and villi increase surface area for absorption.

    • Globular cells produce secretions.

    • Crypt cells produce new cells for the lining of the intestines.

  • Digestive Secretions

    • Various secretions aid in digestion (e.g., enzymes, acids).

  • GI Tract Structure

    • Familiarity with accessory organs and where they fit in the digestion process.

  • Food Movement Through the GI Tract

    • Terms change (e.g., bolus, chyme) as food progresses.

  • Nutrition Assessment Components

    • Different examinations; challenges associated.

  • Nutrient Deficiencies

    • Distinction between primary (due to inadequate intake) and secondary deficiencies (due to absorption or utilization issues).

    • Physical signs of deficiency are not required for this assessment.

  • Key Experiment Principles

    • Understand control groups and blinding in studies.

What are Carbohydrates?

Types of Carbohydrates

  • Monosaccharides

    • Single sugar units (e.g., glucose, fructose, galactose).

  • Disaccharides

    • Two monosaccharides (e.g., maltose = glucose + glucose, sucrose = glucose + fructose, lactose = glucose + galactose).

  • Polysaccharides

    • Long chains of monosaccharides (mostly glucose)—e.g., starch and fiber.

Complex Carbohydrates and Simple Sugars

Monosaccharides

  • Glucose

    • Blood sugar; part of all disaccharides.

  • Fructose

    • Found in fruits; sweetest sugar.

  • Galactose

    • Present in dairy products.

Disaccharides

  • Maltose

    • Found in barley; consists of two glucose units.

  • Lactose

    • Milk sugar; glucose + galactose.

  • Sucrose

    • Common table sugar; glucose + fructose.

Chemical Processes

  • Condensation

    • Creates bonds; water is a by-product.

  • Hydrolysis

    • Breaks down compounds; water is consumed.

The Role of Polysaccharides

  • Glycogen

    • Storage form of glucose in animals; highly branched.

  • Starch

    • Storage form in plants; comprises branched and unbranched chains.

  • Dietary Fiber

    • Non-starch polysaccharides; crucial for gut health.

    • Includes soluble (slows digestion) and insoluble fibers (adds bulk).

Digestive Process of Carbohydrates

  • Initially:

    • No carbohydrate digestion in the stomach; limited energy available for the colon and liver.[

  • Absorption in the Small Intestine

  • Glucose: Active transport when CHO concentration is high.

  • Galactose: Similar absorption method as glucose.

  • Fructose: Facilitated transport; leads to slower blood glucose rise.

Irritable Bowel Syndrome (IBS)

  • Symptoms: Pain, diarrhea/constipation, bloating; involuntary irregularities in GI function.

  • Etiology: Complex; involves physiological and environmental factors, includes dietary influences. Women are more frequently diagnosed.

Low FODMAP Diet as Potential Treatment

  • Definition:

    • Focus on reducing highly fermentable carbs (oligosaccharides, disaccharides, monosaccharides, and polyols) that may exacerbate IBS symptoms.

  • Common Trigger Foods:

    • Dairy, wheat, beans, certain vegetables (e.g., onions, garlic).

Lactose Intolerance

  • Lactase Enzyme: Tends to decrease after childhood; affects absorption of lactose leading to digestive discomfort.

  • Managing Lactose Intolerance:

    • Individualized dietary changes; gradual exposure to lactose may improve tolerance.

    • Use of lactose-free products or enzyme supplements can assist those with intolerance.

Glucose Metabolism

  • Energy Source:

    • Essential for cells; excess glucose turns into glycogen for short-term storage in liver and muscle.

  • Fasting Phase:

    • Liver converts glycogen back to glucose as needed.

  • Long-term Glucose Storage:

    • Excess glucose converted to fat.

Synthesizing Glucose

  • Gluconeogenesis:

    • Uses proteins for glucose synthesis; ketone bodies accumulation can occur if carbohydrates are absent.- Daily Requirement:

    • Minimum of 50–100 grams of carbohydrates recommended to spare protein use.

Hormones Regulating Blood Glucose

  • Insulin and glucagon play essential roles in glucose uptake and metabolism.

Diabetes

  • Type 1 & Type 2:

    • Type 1 involves insulin deficiency, whereas Type 2 is linked to insulin resistance and obesity.

  • Management Goals:

    • Stabilize blood glucose via controlled meals and dietary balance.

Hypoglycemia

  • Low blood glucose levels; symptoms include weakness, anxiety, trembling.

  • Ways to manage: eat more complex carbohydrates, maintain regular meal intervals.

Glycemic Response

  • The rate at which glucose enters the bloodstream impacts blood sugar levels.

  • High Glycemic Foods:

    • Cause rapid fluctuations.

  • Low Glycemic Foods:

    • Provide steady energy and are often accompanied by fiber.

Recommended Intakes of Sugar

  • Daily Recommendations:

    • WHO and FAO suggest less than 10% of total daily calories from added sugars; ideally below 5%.

  • Health Canada Guidelines:

    • Advises limiting processed foods high in overall sodium and sugars.

Added Sugars and Health Effects

  • High consumption linked to obesity, diabetes, cardiovascular disease, and dental issues.

High Fructose Corn Syrup

  • Common in many foods; doesn’t provide same satiety as whole foods; may contribute to fatty liver.

Identifying Added Sugars

  • Recognize various names for sugars in food products (e.g., sucrose, glucose, maltose).

Malnutrition Issues

  • Double Burden: Overnutrition alongside nutrient deficiencies driven by empty calorie foods.

Artificial Sweeteners

  • Considered non-nutritive but can have varying digestive impacts and may contain calories.

Whole Grains and Other Benefits

  • Beneficial for nutrient density; enhances gut health, and helps manage weight.

Recommended Intakes of Starch and Fiber

  • Daily carbohydrate intake recommendations and fiber guidelines vary to promote health.

Benefits of Soluble versus Insoluble Fiber

  • Soluble Fiber: Slows digestion and may lower blood sugar responses.

  • Insoluble Fiber: Helps with bowel regularity and increases stool bulk.