Food Choice and Factors Affecting Nutrient Composition

Food Choice

Food selection is influenced by a variety of factors, both biological and environmental. Understanding these factors is essential for making healthy dietary choices.

• Personal Preferences: Taste, texture, and cultural background can affect food choices.

• Health Considerations: Dietary restrictions, allergies, and health goals (e.g., weight management).

• Availability and Cost: Accessibility of foods and economic factors.

• Social and Psychological Factors: Family, peer influence, and emotional state.

• Knowledge and Education: Awareness of nutrition and healthy eating practices.

Factors Affecting Nutrient Composition of Foods

The nutrient content of foods can vary due to several external and internal factors. These factors impact the quality and quantity of nutrients available for absorption.

• Growing Conditions: Soil quality, climate, and agricultural practices.

• Maturity and Ripeness of Plants: Nutrient levels change as plants mature.

• Food Processing: Methods such as canning, freezing, and drying can alter nutrient content.

• Shipping Conditions: Temperature and handling during transport.

• Storage Time: Prolonged storage can lead to nutrient degradation.

• Cooking Processes: Heat and cooking methods can destroy or enhance certain nutrients.

• Health: The body's ability to absorb nutrients depends on individual health status.

Macronutrient Calculations

Calculating Kilocalories from Macronutrients

Each macronutrient provides a specific amount of energy per gram. Calculating total energy intake is important for dietary planning.

• Carbohydrates: 4 kcal/gram

• Protein: 4 kcal/gram

• Fat: 9 kcal/gram

Example Calculation:

• If a food contains 10g carbohydrates, 4g protein, and 2g fat per serving, and someone eats 6 servings:

• Carbohydrates: kcal

• Protein: kcal

• Fat: kcal

• Total: kcal

Vitamins: Classification and Examples

Fat-Soluble vs. Water-Soluble Vitamins

Vitamins are classified based on their solubility, which affects their absorption, transport, and storage in the body.

Healthy Eating Guidelines

MyPlate and Cultural Adaptations

The USDA's MyPlate model provides a visual guide for balanced eating, emphasizing the importance of fruits, vegetables, grains, and protein. This model can be adapted to various cultural dietary patterns.

• Half the plate: Fruits and vegetables

• One quarter: Grains (preferably whole grains)

• One quarter: Protein (plant or animal-based)

• Dairy or water: On the side

• Cultural flexibility: All cultures can create a healthy plate using local foods

Example: A traditional Chinese plate may include rice (grain), tofu (protein), and a variety of vegetables.

Carbohydrates: Structure and Types

Saccharides: Classification

Carbohydrates are organic molecules composed of carbon, hydrogen, and oxygen. They are classified based on the number of sugar units.

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

• Disaccharides: Two monosaccharides joined together (e.g., maltose, sucrose, lactose)

• Polysaccharides: Long chains of monosaccharides (e.g., starch, glycogen, fiber)

Monosaccharides

Monosaccharides are the simplest carbohydrates and serve as building blocks for more complex sugars.

• Glucose: Most abundant monosaccharide; primary energy source for cells

• Fructose: Found in fruits; sweeter than glucose

• Galactose: Part of lactose in milk

• All three are hexoses (6-carbon sugars)

Disaccharides

Disaccharides are formed by joining two monosaccharides via a glycosidic bond, typically through a dehydration reaction.

Equation for Dehydration Synthesis:

Polysaccharides

Polysaccharides are complex carbohydrates with multiple sugar units. They serve as energy storage and structural components.

• Starch: Plant storage polysaccharide; digestible by humans

• Glycogen: Animal storage polysaccharide; highly branched, stored in liver and muscle

• Fiber: Non-digestible plant polysaccharide; promotes digestive health

Example: Glycogen can be converted to glucose to maintain blood sugar levels.

Additional info:

• Some slides reference essential nutrients, digestive enzymes, and hormones, which are core topics in General Biology and Nutrition.

• Further details on absorption, metabolism, and dietary recommendations may be covered in subsequent slides or lectures.