Nutrition Fundamentals

Key Abbreviations in Nutrition

Understanding common abbreviations is essential for interpreting nutrition guidelines and research.

• DRI: Dietary Reference Intake – a set of reference values used to plan and assess nutrient intakes of healthy people.

• RDA: Recommended Dietary Allowance – the average daily intake level sufficient to meet the nutrient requirements of nearly all (97–98%) healthy individuals.

• UL: Tolerable Upper Intake Level – the highest daily nutrient intake that is likely to pose no risk of adverse health effects.

• EAR: Estimated Average Requirement – the daily intake value estimated to meet the requirement in half of the healthy individuals in a group.

Estimated Energy Requirement (EER)

The EER is the average dietary energy intake predicted to maintain energy balance in a healthy adult.

• Definition: The amount of energy (calories) required to maintain body weight, physical activity, and health.

• Formula:

Metabolism: Anabolism and Catabolism

Metabolism encompasses all chemical reactions in the body, divided into two main processes:

• Anabolism: The synthesis of complex molecules from simpler ones, requiring energy (e.g., building proteins from amino acids).

• Catabolism: The breakdown of complex molecules into simpler ones, releasing energy (e.g., breaking down glucose for energy).

ATP: Adenosine Triphosphate

ATP is the primary energy carrier in cells.

• Function: Stores and supplies energy for cellular processes.

• Equation:

Calorie and Kilocalorie

Calories measure energy in food.

• Calorie: The amount of energy needed to raise the temperature of 1 gram of water by 1°C.

• Kilocalorie (kcal): Equal to 1,000 calories; commonly used on food labels.

Macronutrients and Micronutrients

Macronutrients provide energy and are required in large amounts, while micronutrients are needed in smaller quantities for health.

• Macronutrients: Carbohydrates, proteins, and fats.

• Micronutrients: Vitamins and minerals.

Energy Balance

Energy balance is the relationship between energy intake and energy expenditure.

• Positive energy balance: Intake exceeds expenditure, leading to weight gain.

• Negative energy balance: Expenditure exceeds intake, leading to weight loss.

Acceptable Macronutrient Distribution Ranges (AMDR)

AMDR defines the recommended percentage of total energy intake from each macronutrient.

• Carbohydrates: 45–65% of total calories

• Proteins: 10–35% of total calories

• Fats: 20–35% of total calories

Basal Metabolic Rate (BMR)

BMR is the rate at which the body uses energy while at rest to maintain vital functions.

• Factors affecting BMR: Age, sex, genetics, body composition, and hormone levels.

• Equation: (where S = +5 for males, -161 for females)

Dietary Guidelines and Patterns

USDA Food Patterns

The USDA food patterns group foods based on nutrient content to help individuals meet nutritional needs.

• Food Groups: Fruits, vegetables, grains, protein foods, dairy.

• Purpose: To promote balanced nutrition and prevent chronic diseases.

Choose My Plate

Choose My Plate is a visual guide for healthy eating developed by the USDA.

• Guidelines: Emphasizes portion control and variety from all food groups.

• Example: Half the plate should be fruits and vegetables; grains and protein make up the other half, with a serving of dairy.

DASH Diet

The DASH (Dietary Approaches to Stop Hypertension) diet is designed to lower blood pressure.

• Features: High in fruits, vegetables, whole grains, and low-fat dairy; low in saturated fat and sodium.

• Application: Recommended for individuals with or at risk for hypertension.

Mediterranean Diet

The Mediterranean diet emphasizes plant-based foods, healthy fats, and moderate consumption of fish and poultry.

• Key components: Olive oil, nuts, whole grains, fruits, vegetables, fish, and moderate wine intake.

• Health benefits: Associated with reduced risk of cardiovascular disease.

Nutrition Classifications and Comparisons

Macronutrients vs. Micronutrients

Macronutrients and micronutrients differ in quantity required and function.

Energy Density

Energy density refers to the amount of energy (calories) per gram of food.

• High energy density: Foods with many calories per gram (e.g., oils, nuts).

• Low energy density: Foods with fewer calories per gram (e.g., fruits, vegetables).

Kcal/g Values

Each macronutrient provides a specific amount of energy per gram.

Digestion and Absorption

Major Organs and Accessory Organs

The digestive system includes major and accessory organs that work together to process food.

• Major organs: Mouth, esophagus, stomach, small intestine, large intestine.

• Accessory organs: Liver, pancreas, gallbladder.

• Functions: Accessory organs produce enzymes and bile to aid digestion.

Structure of the Gastrointestinal Tract

The GI tract is a continuous tube from mouth to anus, specialized for digestion and absorption.

• Layers: Mucosa, submucosa, muscularis, serosa.

• Function: Each layer contributes to movement, secretion, and absorption.

Digestion of Macronutrients

Macronutrients are broken down by specific enzymes in the digestive tract.

• Carbohydrates: Digested by amylase and other enzymes into simple sugars.

• Proteins: Digested by proteases into amino acids.

• Fats: Digested by lipases into fatty acids and glycerol.

Vitamins and Minerals

Fat-Soluble vs. Water-Soluble Vitamins

Vitamins are classified based on their solubility.

Functions of Vitamins and Minerals

Vitamins and minerals are essential for various physiological functions.

• Vitamins: Support metabolism, immune function, and cell growth.

• Minerals: Build bones, transmit nerve impulses, regulate fluid balance.

Antioxidants

Antioxidants protect cells from damage caused by free radicals.

• Examples: Vitamins C and E, selenium.

• Function: Reduce oxidative stress and may lower risk of chronic diseases.

Recommended Water Intake

Calculating Water Needs

Water requirements depend on body weight, activity level, and environmental conditions.

• General guideline: About 30–35 mL of water per kg of body weight per day.

• Example: A 70 kg adult needs approximately 2.1–2.45 liters of water daily.

Dietary Patterns Comparison

Mediterranean Diet vs. DASH Diet

Both diets promote heart health but differ in specific recommendations.

Additional info: These notes expand on brief quiz questions to provide a comprehensive overview suitable for exam preparation in a college-level Nutrition course.