Introduction to Nutrition

Food vs. Nutrients

Understanding the distinction between food and nutrients is foundational in nutrition science.

• Food: Any substance consumed to provide nutritional support for the body. It is usually of plant or animal origin and contains essential nutrients.

• Nutrients: Chemical substances in food that are used by the body for growth, maintenance, and repair. Examples include carbohydrates, proteins, fats, vitamins, minerals, and water.

• Example: An apple (food) contains carbohydrates, fiber, vitamin C, and water (nutrients).

Wellness and Its Definition

Wellness is a holistic concept that encompasses physical, mental, and social well-being.

• Wellness: An active process of becoming aware of and making choices toward a healthy and fulfilling life.

• National Wellness Institute Definition: Wellness is a conscious, self-directed, and evolving process of achieving full potential.

Nutrition and Disease

Many leading causes of death are influenced by nutrition.

• Leading Cause of Death in the US: Heart disease.

• Diseases with Strong Nutritional Components:

  • Heart disease

  • Type 2 diabetes

  • Obesity

  • Some cancers (e.g., colorectal cancer)

Factors Influencing Daily Caloric Needs

Caloric needs vary based on several factors.

• Age: Metabolic rate changes with age.

• Gender: Males and females have different energy requirements.

• Physical Activity Level: More active individuals require more calories.

• Additional info: Other factors include body size, composition, and health status.

Essential Nutrients

Essential nutrients are those that the body cannot synthesize in sufficient amounts and must be obtained from the diet.

• Most Essential Nutrient: Water is often considered the most essential because it is required for all bodily functions.

Energy Provided by Nutrients

Different macronutrients provide different amounts of energy.

• Carbohydrates: 4 calories per gram

• Proteins: 4 calories per gram

• Fats: 9 calories per gram

Functions of Macronutrients

• Carbohydrates: Main source of energy for the body, especially the brain and muscles during exercise.

• Proteins: Build and repair tissues, make enzymes and hormones, support immune function.

• Lipids (Fats): Provide energy, support cell growth, protect organs, and help absorb fat-soluble vitamins.

Role of Water in the Body

Water is involved in numerous physiological processes.

• Regulation of body temperature

• Transport of nutrients and waste products

• Lubrication of joints

• Additional info: Water is also essential for chemical reactions and maintaining blood volume.

Obtaining Nutrients

• Sources: Nutrients are obtained from a variety of foods, including fruits, vegetables, grains, proteins, and dairy.

• Balanced Diet: Eating a variety of foods ensures adequate intake of all essential nutrients.

Supplements

• Definition: Products taken orally that contain dietary ingredients intended to supplement the diet.

• When to Use: When dietary intake is insufficient or specific health conditions require supplementation.

• Concerns: Overuse, contamination, and lack of regulation.

Obesity: Causes and Complexity

• Scientific Causes: Energy imbalance (calories in > calories out), genetics, environment.

• Practical Complexity: Social, psychological, and economic factors also play a role.

Trustworthy Nutrition Advice

• Most Trustworthy Source: Registered Dietitian Nutritionist (RDN) due to their education and credentialing.

• Government Role: The US government provides guidelines (e.g., Dietary Guidelines for Americans) to promote public health.

• Scientific Consensus: General agreement among experts based on evidence from multiple studies.

• Retail Advice: Advice from supplement stores may not always be evidence-based; always verify credentials.

Chapter 2: Tools for Healthy Eating

Principles of Healthy Eating

Three key principles guide healthy eating patterns.

• Balance: Consuming the right proportions of foods from all food groups.

• Variety: Including many different foods in the diet to ensure nutrient adequacy.

• Moderation: Avoiding excessive intake of any one food or nutrient.

• Additional info: Proportionality and nutrient density are also important concepts.

Dietary Reference Intakes (DRIs)

DRIs are a set of reference values used to plan and assess nutrient intakes.

• Definition: Quantitative estimates of nutrient intakes to be used for planning and assessing diets for healthy people.

• Determination: Based on scientific evidence and set by expert panels.

Acceptable Macronutrient Distribution Ranges (AMDRs)

AMDRs specify the percentage of total calories that should come from each macronutrient.

• Carbohydrates: 45–65% of total calories

• Fats: 20–35% of total calories

• Proteins: 10–35% of total calories

Estimated Energy Requirement (EER)

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

• Three Main Themes:

  • Basal metabolic rate (BMR)

  • Physical activity

  • Thermic effect of food

• Formula:

Dietary Guidelines for Americans

• Purpose: To provide science-based advice for people aged 2 years and older to promote health and reduce risk of chronic diseases.

• Target Audience: Policymakers, health professionals, and nutrition educators.

Nutrient Density vs. Caloric Density

• Nutrient Density: The amount of nutrients per calorie of food.

• Caloric (Energy) Density: The amount of calories per gram or serving of food.

• Example: Vegetables are nutrient-dense but low in calories; fried foods are energy-dense but low in nutrients.

Portion vs. Serving Size

• Portion: The amount of food you choose to eat at one time.

• Serving Size: A standardized amount of food, such as a cup or ounce, used to quantify recommended amounts.

• Example: A portion may be two cups of pasta, while the serving size is one cup.