Lesson 1

Balanced diet: macro/micro nutrients

<p>Learn about Balanced diet: macro/micro nutrients in this comprehensive lesson.</p>

Overview

A balanced diet is crucial for maintaining good health, growth, and energy. It involves consuming the right proportions of various nutrients to meet the body's needs. These nutrients are broadly categorised into macronutrients and micronutrients, each playing distinct and vital roles in bodily functions. Macronutrients, such as carbohydrates, proteins, and fats, are required in large quantities as they provide the bulk of the energy and building blocks for the body. Micronutrients, including vitamins and minerals, are needed in smaller amounts but are equally essential for regulating metabolism, maintaining immune function, and supporting overall physiological processes. Water and fibre are also critical components of a balanced diet, contributing to hydration, digestion, and waste elimination. Understanding the function of each nutrient and the consequences of their deficiency or excess is fundamental to making informed dietary choices. This topic explores the specific roles of each nutrient, their sources, and how a balanced intake contributes to preventing deficiency diseases and promoting long-term well-being.

Key Concepts

  • Balanced Diet: A diet providing all necessary nutrients in correct proportions for health.
  • Macronutrients: Nutrients required in large quantities for energy and building (carbohydrates, proteins, fats).
  • Micronutrients: Nutrients required in small quantities for regulating body processes (vitamins, minerals).
  • Carbohydrates: Primary energy source; found in sugars and starches.
  • Proteins: Essential for growth, repair, enzymes, and antibodies; found in meat, fish, beans.
  • Fats (Lipids): Concentrated energy, insulation, organ protection; found in oils, nuts, butter.
  • Vitamins: Organic compounds vital for specific body functions (e.g., Vitamin A for vision, Vitamin C for immunity).
  • Minerals: Inorganic substances vital for body functions (e.g., Calcium for bones, Iron for blood).
  • Water: Essential solvent, transport medium, temperature regulation.
  • Fibre (Roughage): Indigestible plant material that aids digestion and prevents constipation.
  • Deficiency Disease: Illness caused by a lack of a specific nutrient (e.g., Scurvy from Vitamin C deficiency).
  • Rickets: Bone softening in children due to Vitamin D or Calcium deficiency.

Introduction to a Balanced Diet

A balanced diet is a diet that contains the right amounts of all the nutrients required by the body to function correctly, grow, and repair itself. It ensures that the body receives adequate energy and all the necessary components for health.

Components of a Balanced Diet:

  • Macronutrients: Needed in large quantities.
    • Carbohydrates
    • Proteins
    • Fats
  • Micronutrients: Needed in small quantities.
    • Vitamins
    • Minerals
  • Other Essential Components:
    • Water
    • Fibre (roughage)

The specific requirements for a balanced diet can vary depending on several factors:

  • Age: Growing children and adolescents need more nutrients.
  • Sex: Males generally require more calories than females.
  • Activity Level: Active individuals need more energy-providing nutrients.
  • Health Status: Pregnant women, lactating mothers, or those recovering from illness have different nutritional needs.
  • Environmental Conditions: People in cold climates may need more energy.

Macronutrients: Carbohydrates, Proteins, and Fats

Macronutrients are nutrients required in large amounts by the body, primarily for energy and building materials.

Carbohydrates

  • Function: Primary source of energy for the body, especially for the brain and muscles. Stored as glycogen in the liver and muscles.
  • Sources:
    • Sugars (simple carbohydrates): Glucose, fructose, sucrose (fruits, honey, table sugar).
    • Starches (complex carbohydrates): Bread, pasta, rice, potatoes, cereals.
  • Deficiency: Lack of energy, fatigue, weight loss.

Proteins

  • Function: Essential for growth and repair of tissues, production of enzymes, hormones, and antibodies. Can be used as an energy source if carbohydrates and fats are insufficient.
  • Sources: Meat, fish, eggs, dairy products, beans, lentils, nuts.
  • Deficiency: Stunted growth, muscle wasting, oedema (swelling due to fluid retention), weakened immune system (e.g., Kwashiorkor in children).

Fats (Lipids)

  • Function: Concentrated source of energy, insulation against cold, protection of organs, absorption of fat-soluble vitamins (A, D, E, K), component of cell membranes.
  • Sources: Butter, oils, nuts, seeds, fatty fish, avocado.
  • Deficiency: Weight loss, difficulty absorbing fat-soluble vitamins, poor insulation.
  • Excess: Obesity, increased risk of heart disease.

Micronutrients: Vitamins

Micronutrients are nutrients required in small amounts, but are vital for regulating body processes.

Vitamins

Organic compounds essential for normal growth and nutrition, required in small quantities.

1. Fat-Soluble Vitamins (A, D, E, K): Stored in the body's fatty tissues.

  • Vitamin A (Retinol):
    • Function: Good vision (especially in dim light), healthy skin, immune function.
    • Sources: Carrots, liver, dairy, eggs, leafy green vegetables.
    • Deficiency: Night blindness, dry eyes, impaired immune function.
  • Vitamin D:
    • Function: Helps absorb calcium and phosphorus for strong bones and teeth.
    • Sources: Sunlight exposure (skin synthesises it), oily fish, fortified milk/cereals.
    • Deficiency: Rickets (soft bones) in children, osteomalacia (soft bones) in adults.
  • Vitamin E:
    • Function: Antioxidant, protects cells from damage.
    • Sources: Vegetable oils, nuts, seeds, leafy green vegetables.
  • Vitamin K:
    • Function: Essential for blood clotting.
    • Sources: Leafy green vegetables (spinach, kale), broccoli.

2. Water-Soluble Vitamins (B-complex, C): Not stored in the body, must be consumed regularly.

  • Vitamin C (Ascorbic Acid):
    • Function: Healthy gums, skin, and blood vessels; wound healing; immune function; antioxidant.
    • Sources: Citrus fruits, berries, bell peppers, broccoli.
    • Deficiency: Scurvy (bleeding gums, poor wound healing, joint pain).
  • B Vitamins (e.g., B1, B2, B3, B12):
    • Function: Involved in metabolism, energy release from food, nerve function, red blood cell formation.
    • Sources: Whole grains, meat, eggs, dairy, leafy greens.
    • Deficiency: Beriberi (B1 - nerve damage), Pellagra (B3 - skin, digestive, neurological issues), Anaemia (B12 - fatigue, weakness).

Micronutrients: Minerals, Water, and Fibre

Minerals

Inorganic substances required for various body functions.

  • Calcium:
    • Function: Strong bones and teeth, muscle contraction, nerve function, blood clotting.
    • Sources: Dairy products, leafy green vegetables, fortified foods.
    • Deficiency: Rickets (children), Osteoporosis (adults - brittle bones), poor teeth development.
  • Iron:
    • Function: Component of haemoglobin in red blood cells, transports oxygen around the body.
    • Sources: Red meat, liver, leafy green vegetables, fortified cereals.
    • Deficiency: Anaemia (fatigue, weakness, pale skin).
  • Sodium:
    • Function: Fluid balance, nerve function, muscle contraction.
    • Sources: Table salt, processed foods.
    • Excess: High blood pressure (hypertension).
  • Iodine:
    • Function: Essential for thyroid hormones, which regulate metabolism.
    • Sources: Seafood, iodised salt.
    • Deficiency: Goitre (enlarged thyroid gland), developmental issues.

Water

  • Function: Solvent for chemical reactions, transports nutrients and waste, regulates body temperature, lubricates joints, component of cells and tissues.
  • Sources: Drinking water, beverages, fruits, vegetables.
  • Deficiency (Dehydration): Fatigue, headaches, dizziness, impaired bodily functions.

Fibre (Roughage)

  • Function: Adds bulk to food, aids peristalsis (movement of food through the digestive tract), prevents constipation, helps regulate blood sugar and cholesterol levels.
  • Sources: Whole grains, fruits, vegetables, legumes.
  • Deficiency: Constipation, increased risk of bowel disorders.

Exam Tips

  • •**Know the 'Big 7':** Be able to list carbohydrates, proteins, fats, vitamins, minerals, water, and fibre as the main components of a balanced diet.
  • •**Link Nutrient to Function and Source:** For each major nutrient, be able to state its primary function, good dietary sources, and the symptoms of its deficiency (and sometimes excess). Use tables for revision.
  • •**Understand Individual Needs:** Remember that dietary requirements vary based on age, sex, activity level, and health status. Be ready to explain why.
  • •**Distinguish Macro vs. Micro:** Clearly differentiate between macronutrients (large amounts, energy/building) and micronutrients (small amounts, regulatory).
  • •**Practice Deficiency Diseases:** Pay close attention to common deficiency diseases like scurvy, rickets, anaemia, and Kwashiorkor, and link them to the specific nutrient deficiency.