Nutrition in humans is the process by which the body takes in food, digests it, absorbs useful substances called nutrients, and uses them for energy, growth, repair, and protection. Every activity we perform—walking, thinking, breathing, studying, playing, or sleeping—depends on proper nutrition.
Humans cannot make their own food like plants. Instead, we depend on a variety of foods such as grains, fruits, vegetables, milk, eggs, meat, and pulses. These foods contain different nutrients like carbohydrates, proteins, fats, vitamins, minerals, and water. Each nutrient has a specific role in keeping the body healthy and functioning smoothly.
Nutrition is not just about eating food. It also includes how food is broken down by the digestive system, how nutrients are absorbed into the blood, and how they are used by different body parts like the brain, muscles, bones, and organs. Poor nutrition can lead to weakness, disease, poor growth, and low immunity, while balanced nutrition helps us stay active, strong, and healthy.
What Is Food?
Food is any substance that we eat or drink to obtain energy and nutrients required for life. Food provides:
- Energy to perform activities
- Materials for growth and repair
- Substances that protect us from diseases
What Are Nutrients?
Nutrients are useful substances present in food that are needed by the body. The main nutrients required by humans are:
- Carbohydrates
- Proteins
- Fats
- Vitamins
- Minerals
- Water
Process of Nutrition in Humans
Nutrition in humans occurs in five main steps:
1. Ingestion
The process of taking food into the mouth.
2. Digestion
Breaking down complex food into simple, soluble substances with the help of digestive juices.
3. Absorption
Digested nutrients are absorbed into the blood through the small intestine.
4. Assimilation
Absorbed nutrients are transported to different body cells and used for energy, growth, and repair.
5. Egestion
Removal of undigested and waste materials from the body.
Digestive System and Nutrition
The digestive system includes:
- Mouth
- Oesophagus
- Stomach
- Small intestine
- Large intestine
Each part helps convert food into nutrients that the body can use.
Major Nutrients and Their Functions
1. Carbohydrates
Carbohydrates are the main source of energy for the body.
Sources:
- Rice
- Wheat
- Bread
- Potatoes
- Sugar
Functions:
- Provide instant energy
- Support brain activity
- Help in daily physical work
Examples: Glucose, starch
2. Proteins
Proteins are body-building nutrients.
Sources:
- Pulses
- Eggs
- Milk
- Meat
- Fish
- Soybean
Functions:
- Growth of body tissues
- Repair of damaged cells
- Formation of muscles, skin, and enzymes
3. Fats
Fats are concentrated sources of energy.
Sources:
- Butter
- Ghee
- Oil
- Nuts
- Cheese
Functions:
- Store energy
- Keep the body warm
- Protect internal organs
- Help absorb vitamins A, D, E, and K
4. Vitamins
Vitamins are protective nutrients needed in small amounts.
Types and Functions:
- Vitamin A – Good vision and skin
- Vitamin B – Energy metabolism
- Vitamin C – Immunity and wound healing
- Vitamin D – Strong bones
- Vitamin K – Blood clotting
Sources: Fruits, vegetables, milk, sunlight
5. Minerals
Minerals are inorganic nutrients essential for body structure and function.
Important Minerals:
- Calcium – Bones and teeth
- Iron – Hemoglobin formation
- Iodine – Thyroid function
- Sodium & Potassium – Nerve and muscle function
6. Water
Water is essential for life.
Functions:
- Transport nutrients
- Remove waste products
- Regulate body temperature
- Aid digestion
Role of Nutrition in the Human Body
Energy Production
Carbohydrates and fats provide energy for:
- Walking
- Running
- Thinking
- Breathing
Growth
Proteins, minerals, and vitamins help in:
- Muscle development
- Bone growth
- Overall body growth
Repair and Maintenance
Nutrition helps:
- Repair damaged tissues
- Heal wounds
- Replace old cells
Protection from Diseases
Vitamins and minerals strengthen the immune system and protect against infections.
Balanced Diet
A balanced diet contains all nutrients in the right proportion.
Components of a Balanced Diet
- Carbohydrates
- Proteins
- Fats
- Vitamins
- Minerals
- Water
- Roughage (dietary fiber)
A balanced diet keeps us:
- Healthy
- Active
- Disease-free
Importance of Roughage (Dietary Fiber)
Roughage:
- Helps in digestion
- Prevents constipation
- Improves gut health
Sources: Fruits, vegetables, whole grains
Malnutrition
Malnutrition occurs when the body does not get proper nutrition.
Types of Malnutrition
- Undernutrition – Lack of nutrients
- Overnutrition – Excess intake of nutrients
Diseases Caused by Malnutrition
- Kwashiorkor
- Marasmus
- Anemia
- Rickets
Common Nutrition-Related Problems
- Weakness and fatigue
- Poor growth in children
- Low immunity
- Bone disorders
- Obesity
FAQs – Nutrition in Humans
1. Why do humans need nutrition?
To obtain energy, grow, repair tissues, and stay healthy.
2. Which nutrient gives instant energy?
Carbohydrates.
3. Which nutrient helps in body building?
Proteins.
4. Why are vitamins called protective foods?
They protect the body from diseases.
5. What is a balanced diet?
A diet containing all nutrients in proper amounts.
6. Can we live without fats?
No, fats are essential in small quantities.
7. Why is water important in nutrition?
It helps digestion, absorption, and waste removal.
8. What happens if we lack iron?
It causes anemia and weakness.
9. Which nutrient helps in bone strength?
Calcium and vitamin D.
10. What is malnutrition?
A condition caused by lack or excess of nutrients.
