Deficiency of vitamin A most characteristically causes which condition?

The human body requires six major nutrients: carbohydrates (energy source), proteins (growth and repair), fats (energy storage and insulation), vitamins (regulatory functions), minerals (bone and metabolic functions), and water. Each nutrient plays a specific role in maintaining health. A balanced diet includes all these nutrients in proper proportions.

Vitamins are organic compounds required in small quantities for normal body function. They are classified as fat-soluble (A, D, E, K) and water-soluble (B-complex, C). Vitamin A maintains vision, D helps calcium absorption, C builds immunity and prevents scurvy, B1 (thiamine) prevents beriberi, and B12 is essential for nerve function and blood formation.

Nutrient deficiency diseases include: Scurvy (Vitamin C deficiency), Rickets (Vitamin D deficiency in children), Beriberi (Vitamin B1/thiamine), Night blindness (Vitamin A), Anaemia (Iron or B12 deficiency), Goitre (Iodine deficiency), Kwashiorkor and Marasmus (protein-energy malnutrition), and Pellagra (Niacin/Vitamin B3 deficiency).

Carbohydrates provide immediate energy (4 kcal/g) and are found in rice, wheat, and fruits. Proteins are building blocks made of amino acids (4 kcal/g), essential for growth and repair, found in eggs, meat, legumes. Fats store energy (9 kcal/g), insulate organs, and aid vitamin absorption; found in oils, butter, nuts.

A balanced diet contains all essential nutrients — carbohydrates, proteins, fats, vitamins, minerals, and water — in the right proportions. It supports growth, maintains energy, boosts immunity, and prevents deficiency diseases. ICMR recommends a daily intake that includes cereals, pulses, vegetables, fruits, dairy, and adequate water.