Introduction to Nutrition: Key Concepts and Influences

Chapter 1: What Is Nutrition?

Learning Outcomes

This chapter introduces the foundational concepts of nutrition, including the definition of nutrition, the essential nutrients, factors influencing food choices, and the importance of a balanced diet. Students will also learn about the current nutritional state of the American diet and how to identify reliable sources of nutrition information.

• Discuss the factors that influence food choices.

• Define the term nutrition.

• Differentiate between the six categories of essential nutrients found in food and in the body.

• Understand the importance of a well-balanced diet in meeting daily nutrient needs.

• Discuss the current nutritional state of the American diet.

• Understand the scientific method in nutrition research and identify reliable sources of nutrition information.

Factors That Drive Our Food Choices

Basic Need for Nutrients

Humans need to eat and drink to obtain nutrients, which are chemical compounds in foods that provide fuel for energy, growth, maintenance, and regulation of body processes.

• Nutrients: Chemical compounds in foods essential for energy, growth, maintenance, and regulation of body processes.

• Six Classes of Nutrients:

  • Carbohydrates, lipids, proteins: Provide energy in the form of kilocalories (commonly referred to as calories).

  • Vitamins, minerals, water: Help regulate many body processes, including metabolism.

• Nonnutrient Compounds: Some foods also provide nonnutrient compounds that contribute to health and may play a role in fighting chronic diseases.

Other Influences on Food Choices

While the need for nutrients is fundamental, many other factors influence food choices beyond basic nutrition.

• Taste and Culture: Personal preferences and cultural traditions strongly affect food selection.

• Social Reasons and Trends: Social gatherings, peer influence, and popular trends can shape eating habits.

• Cost, Time, and Convenience: Economic factors, time constraints, and convenience often determine what foods are chosen.

• Habits and Emotions: Established routines and emotional states (such as stress or happiness) can impact food choices.

Definition of Nutrition

What Is Nutrition?

Nutrition is the science that studies how nutrients and compounds in foods nourish the body, support function, and affect health. Good nutrition is essential for maintaining health and preventing chronic diseases.

• Nutrition: The study of how food and its components affect body functions and health.

• Importance: Chronic deficiencies, excesses, and imbalances of nutrients can affect long-term health and increase the risk of diseases such as heart disease, cancer, diabetes, and stroke.

Essential Nutrients

Categories of Essential Nutrients

There are six categories of essential nutrients required to maintain bodily function. These are divided into macronutrients and micronutrients.

• Macronutrients: Energy-yielding nutrients needed in larger amounts.

  • Carbohydrates

  • Lipids (fats)

  • Proteins

• Micronutrients: Needed in smaller amounts.

  • Vitamins

  • Minerals

• Water: Required in copious amounts daily for hydration and physiological processes.

Energy Provided by Macronutrients

Macronutrients supply energy, measured in kilocalories (kcal). The amount of energy provided by each macronutrient is as follows:

• Carbohydrates: 4 kcal/gram

• Proteins: 4 kcal/gram

• Fats: 9 kcal/gram

Formula to calculate energy from food:

$\text{Total Energy (kcal)} = (\text{grams of carbohydrate} \times 4) + (\text{grams of protein} \times 4) + (\text{grams of fat} \times 9)$

Functions of Macronutrients

• Carbohydrates: Supply glucose, the major energy source for the body.

• Fats: Provide energy, cushion organs, and insulate the body to maintain temperature.

• Proteins: Can provide energy but are primarily used for growth, maintenance of muscle, tissues, organs, making hormones, enzymes, and supporting the immune system.

Functions of Micronutrients and Water

• Vitamins and Minerals: Essential for metabolism; many act as coenzymes assisting enzymes in chemical reactions (e.g., B vitamins in carbohydrate and fat metabolism).

• Water: Vital for chemical reactions, maintaining body temperature, transporting nutrients and oxygen, removing waste, lubricating joints, and protecting organs.

Additional info:

• Phytochemicals: Nonnutritive compounds in plant foods that may help fight chronic diseases.

• Fiber: The portion of plant foods not digested in the small intestine; found in whole grains, fruits, and vegetables.