Classes and Functions of Nutrients

1. Vitamins: Organic compounds that help regulate various body processes.
2. Minerals: Inorganic elements that support structural and regulatory functions.

While micronutrients are found in most foods, fresh foods are often the best natural sources, though many processed foods are fortified with added vitamins and minerals.

Water: The Essential Macronutrient

Water is unique because it is required by the body in large amounts, classifying it as a macronutrient, yet it provides zero energy. Water is a fundamental component of human biology, making up approximately $60%$ of a healthy human body.

The Three Functions of Nutrients

Nutrients do not work in isolation; they work together to maintain the body's health through three primary functions: energy provision, structural formation, and the regulation of body processes.

1. Energy Provision

The body uses biochemical reactions to release the energy stored within carbohydrates, fats, and proteins. This energy is used to fuel physical activity and maintain essential internal body functions.

Note on Energy Balance: If you consume more energy (kcalories) than your body requires for its daily activities, that excess energy will be stored, and body weight will increase over time.

2. Forming Body Structures

Nutrients are the building blocks of the human body. Most of our body weight is derived from water, fat, and protein.

• Proteins are critical for forming ligaments and tendons that connect bones and muscles.
• Lipids (fats) and proteins are the primary components of the membranes that surround every cell in the body.
• Minerals like calcium and phosphorus are essential for hardening teeth and bones.

3. Regulating Body Processes (Metabolism and Homeostasis)

All the chemical reactions occurring within the body are collectively known as metabolism. The body's ability to regulate these metabolic reactions to maintain a stable internal environment is called homeostasis.

Each nutrient plays a specific role in this regulatory process:

• Vitamins and Minerals: Help speed up or slow down metabolic reactions (e.g., B vitamins regulate the use of macronutrients for energy).
• Water: Helps regulate body temperature, such as through sweating.
• Hormones: Certain lipids (like estrogen) and proteins (like leptin) act as signals to regulate reproductive cycles or fat stores.

Understanding Malnutrition

When the intake of nutrients is imbalanced, it results in a condition known as malnutrition. Malnutrition does not simply mean "not eating enough"; it refers to any imbalance in nutrient intake. It is categorized into two types:

1. Undernutrition: This occurs when a person consumes insufficient amounts of energy-providing foods or essential nutrients.
2. Overnutrition: This occurs when there is an excess consumption of energy-providing foods.

In modern diets, particularly in Canada, overnutrition is a significant concern. High consumption of processed foods often leads to an excess of sodium, saturated fats, and sugars, contributing to overweight and obesity.

Exam Tip: Remember that malnutrition is a spectrum. It includes both the deficiency of nutrients (undernutrition) and the excess of nutrients (overnutrition).

Summary Table of Nutrient Functions

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Sources: Lecture1_Chapter1 textbook 52 slides_copyright.pdf