Nutrients
Nutrients are the fundamental substances required by living organisms to survive and function properly. Think of them as the input materials that keep the body running.
They perform four essential roles:
- Growth (building new tissues)
- Energy production (fuel for activities)
- Repair (healing damaged tissues)
- Maintenance of life processes (like digestion, respiration, immunity)
Classification of Nutrients
Nutrients are broadly divided into two categories based on the quantity required by the body:
(A) Macronutrients
These are required in large amounts and form the bulk of our diet.
They:
- Provide energy
- Support growth and structure
Examples → Carbohydrates, Proteins, Lipids (fats), Water
👉 Water, although not an energy source, is extremely crucial because:
- It helps in absorption of nutrients
- It assists in removal of waste through urine and sweat
(B) Micronutrients
These are required in small amounts, but their importance is no less. Examples → Vitamins, Minerals. They mainly regulate → Metabolism, Immunity, Physiological balance
Biomolecules
Now, all these nutrients ultimately exist in the form of biomolecules.
Biomolecules are:
- Organic compounds essential for life
- Made primarily of Carbon (C), Hydrogen (H), Oxygen (O), Nitrogen (N)
- Sometimes also include Phosphorus (P) and Sulphur (S)
Four Major Types of Biomolecules
- Carbohydrates → Primary energy source
- Proteins → Structure + enzymes + repair
- Lipids → Energy storage + insulation
- Nucleic acids (DNA/RNA) → Genetic information
Biomacromolecules vs Biomicromolecules
This is a very important conceptual distinction.
| Feature | Biomacromolecules | Biomicromolecules |
| Definition | Large molecules (> 10,000 Daltons) | Small molecules (< 1000 Daltons) |
| Structure | Complex, polymeric (repeating units) | Simple, monomeric |
| Acid Solubility | Insoluble | Soluble |
| Function | Structural support, genetic storage, energy storage | Building blocks + quick energy |
| Examples | Proteins, DNA/RNA, polysaccharides | Amino acids, monosaccharides, nucleotides, fatty acids |
👉 Key Insight:
Biomicromolecules are the building blocks, while biomacromolecules are the final structures.
For example:
- Amino acids → Proteins
- Monosaccharides → Polysaccharides
Deficiency Diseases – When Nutrients are Lacking
If the body does not receive adequate nutrients over a prolonged period, it leads to deficiency diseases.
Major Deficiencies and Their Effects
| Nutrient | Deficiency Disease / Symptoms |
| Protein | – Kwashiorkor (edema, stunted growth) – Marasmus (severe wasting, energy deficiency) |
| Carbohydrates | – Hypoglycemia (low blood sugar) – Ketoacidosis (excess ketones, acidic blood) |
| Fats | – Dry skin – Hormonal imbalance – Poor brain function |
| Vitamins & Minerals | Various diseases (covered in upcoming sections) |
Important Concepts:
- Edema → Swelling due to fluid accumulation in tissues
- Ketosis → Body burns fat due to lack of carbohydrates
- Ketoacidosis → Dangerous condition where ketone levels become excessively high
👉 So, the body shifts from carbohydrate metabolism → fat metabolism, which can become harmful if uncontrolled.
Balanced Diet – The Preventive Strategy
A balanced diet means → All nutrients are present in the right proportion according to body requirements
It ensures → Proper growth, Efficient functioning, Prevention of deficiency diseases