Sources of Nutrients and Deficiency diseases | Lucent For GK - UPSC PDF Download

Nutrients

By definition, a nutrient is any substance that is absorbed by the body and either provides energy or enables growth, repair or proper functioning of tissues and organs.

• There are seven main classes of nutrients that the body needs: carbohydrates, proteins, fats, vitamins, minerals, fibre and water.
• It is important that everyone consumes these seven nutrients on a daily basis to build the body and maintain health.
• Deficiencies, excesses and imbalances in diet can produce adverse effects on health and lead to specific deficiency diseases or metabolic disorders.
• The following sections list each nutrient class, their common dietary sources, principal functions, and characteristic deficiency conditions, together with brief notes on prevention and examples.

Essential Nutrients

Essential nutrients are those that the human body cannot synthesise in sufficient amounts and therefore must be obtained from the diet. This group includes certain amino acids, essential fatty acids, some vitamins and several minerals. A balanced diet supplies essential nutrients in appropriate proportions.

List of Nutrient Sources and their Deficiency diseases

The sections below describe each nutrient class in a concise, exam-oriented format: definition, principal functions, common dietary sources, notable deficiency diseases and practical prevention measures.

Carbohydrates

• Function: Main source of immediate energy for the body and brain; spare proteins from being used as fuel.
• Sources: Cereals (rice, wheat, maize), pulses, potatoes, fruits, sugar and milk (lactose).
• Deficiency and effects: Low carbohydrate intake causes fatigue, low energy and can lead to ketosis if the body breaks down fats for energy; prolonged inadequate calorie intake contributes to malnutrition.
• Prevention: Include adequate whole grains, fruits and starchy vegetables to meet daily energy needs.
• Notes: Excessive simple sugars increase risk of obesity and type 2 diabetes; emphasis should be on complex carbohydrates and fibre-rich choices.

Proteins

• Function: Provide amino acids for growth, repair and maintenance of body tissues, enzymes, hormones and antibodies.
• Sources: Animal sources - meat, fish, eggs, milk and dairy; plant sources - legumes (lentils, beans), peas, soy, nuts and some cereals.
• Deficiency diseases: Protein-energy malnutrition (PEM) which includes marasmus (severe calorie and protein deficiency) and kwashiorkor (protein deficiency with oedema, fatty liver and growth failure).
• Prevention: Ensure adequate intake of high-quality protein; combine cereals and pulses to improve amino-acid balance in vegetarian diets.
• Notes: Young children, pregnant and lactating women, and adolescents have higher protein requirements.

Fats (Lipids)

• Function: Concentrated source of energy; provide essential fatty acids (linoleic and alpha-linolenic acids), insulation, structural components of cell membranes and aid absorption of fat-soluble vitamins (A, D, E, K).
• Sources: Vegetable oils, ghee, butter, nuts, seeds, fatty fish and animal fats.
• Deficiency and effects: Total fat deficiency is uncommon but insufficient intake of essential fatty acids leads to dry scaly skin, poor wound healing and impaired growth in children.
• Excess: High intake of saturated and trans fats increases risk of cardiovascular disease and obesity.
• Prevention: Use moderate amounts of unsaturated vegetable oils and include sources of omega-3 (fish, flaxseed) and omega-6; limit trans fats and excessive saturated fats.

Vitamins

Vitamins are organic compounds required in small amounts for biochemical functions. Vitamins are classified as fat-soluble (A, D, E, K) and water-soluble (B-complex and C).

• Vitamin A
  Sources: Liver, milk and milk products, eggs, green leafy vegetables, orange and yellow fruits (carrots, mango).
  Deficiency disease: Night blindness and xerophthalmia (drying of conjunctiva and cornea); increases susceptibility to infections.
  Prevention: Vitamin A supplementation programmes, dietary diversity and consumption of coloured fruits and vegetables.
• Vitamin D
  Sources: Sunlight (skin synthesis), fortified milk, fish liver oils.
  Deficiency disease: Rickets in children (bone deformities) and osteomalacia in adults (bone pain, weakness).
  Prevention: Adequate sunlight exposure, dietary sources and supplementation where sunlight is inadequate.
• Vitamin C (Ascorbic acid)
  Sources: Citrus fruits, guava, tomato, green leafy vegetables.
  Deficiency disease: Scurvy - bleeding gums, petechiae, poor wound healing and general weakness.
  Prevention: Fresh fruits and vegetables daily; citrus or guava are inexpensive sources.
• Vitamin B complex
  Important types and deficiency conditions:
  Thiamine (B1): Deficiency causes beri-beri - peripheral neuropathy and cardiac symptoms.
  Riboflavin (B2): Deficiency leads to cheilosis, sore throat and sore tongue.
  Niacin (B3): Deficiency causes pellagra - dermatitis, diarrhoea and dementia.
  Cobalamin (B12): Deficiency causes megaloblastic anaemia and neurological problems.
  Folate (folic acid): Deficiency causes megaloblastic anaemia and in pregnancy is associated with neural tube defects in the foetus.
  Sources: Whole grains, pulses, meat, eggs, dairy, green vegetables and fortified cereals.
  Prevention: Diverse diet; folic acid and iron supplementation programmes for pregnant women; fortification where appropriate.
• Vitamin K
  Sources: Green leafy vegetables, produced by gut flora.
  Deficiency: Bleeding tendency; newborns are given vitamin K to prevent haemorrhagic disease.
• Vitamin E
  Sources: Vegetable oils, nuts and seeds.
  Deficiency: Rare; may cause haemolytic anaemia in susceptible individuals.

Minerals

Minerals are inorganic elements needed for many structural and regulatory functions.

• Iron
  Sources: Red meat, green leafy vegetables, legumes, fortified cereals.
  Deficiency disease: Iron-deficiency anaemia - pallor, fatigue, reduced work capacity and impaired cognitive development in children.
  Prevention: Iron-rich diet, iron and folic acid supplementation, fortification and promoting vitamin C intake to enhance absorption.
• Iodine
  Sources: Iodised salt, seafood, dairy products.
  Deficiency disease: Goitre (thyroid enlargement), hypothyroidism and in severe deficiency during pregnancy cretinism (mental retardation, stunted growth) in offspring.
  Prevention: Use of iodised salt; public health iodine supplementation where needed.
• Calcium
  Sources: Milk and dairy products, green leafy vegetables, fortified foods.
  Deficiency disease: In children, poor bone mineralisation leads to rickets; in adults, osteomalacia and long-term low intake contributes to osteoporosis.
  Prevention: Adequate dietary calcium and vitamin D; weight-bearing exercise to maintain bone strength.
• Zinc
  Sources: Meat, shellfish, legumes, nuts and seeds.
  Deficiency effects: Growth retardation, impaired immunity, delayed wound healing and loss of appetite.
• Other minerals such as selenium, magnesium, phosphorus, potassium and sodium are essential for specialised functions; imbalance produces characteristic clinical features (muscle cramps, cardiac arrhythmias, fluid imbalance) and should be managed medically.

Fibre (Dietary Fibre)

• Function: Adds bulk to intestinal contents, aids regular bowel movements, helps control blood glucose and reduces blood cholesterol.
• Sources: Whole grains, bran, fruits, vegetables, pulses, nuts and seeds.
• Deficiency effects: Low fibre intake causes constipation, increased risk of diverticular disease and may increase long-term risk of colorectal cancer.
• Prevention: Include whole grains, vegetables and fruits daily; increase fibre gradually with adequate fluid intake.

Water

• Function: Universal solvent and medium for biochemical reactions; transports nutrients and waste, maintains body temperature and supports blood volume and circulation.
• Sources: Drinking water, beverages, soups, fruits and vegetables (many foods contain 60-95% water).
• Deficiency disease: Dehydration - headache, dizziness, decreased urine output, severe electrolyte disturbances and in extreme cases shock.
• Prevention: Regular fluid intake, more during hot weather or physical activity; treat drinking water to prevent waterborne diseases.

Practical guidance and public-health measures

• Balanced diet: A varied diet combining cereals, pulses, vegetables, fruits, dairy, and small amounts of oils and sugar meets most nutrient requirements.
• Fortification and supplementation: Fortified staple foods (iodised salt, iron-fortified flour) and targeted supplementation (iron and folic acid for pregnant women, vitamin A for young children) address population-level deficiencies.
• Special needs: Infants, children, adolescents, pregnant and lactating women, and the elderly have altered nutrient needs and may require dietary counselling or supplements.
• Food safety and diversity: Safe water and appropriate food storage prevent infection; dietary diversity reduces risk of single-nutrient deficiencies.
• When to seek medical advice: Persistent signs such as excessive fatigue, unexplained weight loss, swelling, bleeding gums, bone deformities or developmental delays require clinical assessment and appropriate laboratory tests.

Summary

Understanding the seven classes of nutrients-carbohydrates, proteins, fats, vitamins, minerals, fibre and water-their dietary sources, functions and characteristic deficiency disorders is essential for personal health and for planning public-health interventions. Prevention relies on a balanced diet, appropriate fortification and supplementation where necessary, and public-health measures such as iodised salt and safe drinking water.