Food Components
Food Components
What you'll learn
- The six major nutrients and their roles.
- What constitutes a balanced diet.
- Deficiency diseases caused by nutrient shortages.
- Tests to detect nutrients in food.
Key concepts
Six major nutrients
| Nutrient | Main role | Food sources |
|---|---|---|
| Carbohydrates | Energy (primary fuel) | Rice, wheat, bread, potato, sugar |
| Proteins | Growth, repair, build muscles | Pulses, eggs, milk, meat, soybean |
| Fats | Energy store, insulation, absorb fat-soluble vitamins | Butter, oil, nuts, cheese |
| Vitamins | Regulate body processes; protect from disease | Fruits, vegetables, dairy |
| Minerals | Strong bones/teeth, blood, nerve function | Milk (Ca), fish (I), green veg (Fe) |
| Water | Transport nutrients, regulate temperature, remove waste | Water, fruits, vegetables |
| Roughage (Dietary fibre) | Aids digestion; prevents constipation | Whole grains, fruits, vegetables |
Roughage is not a nutrient (body doesn't digest it) but is essential for healthy digestion.
Vitamins in detail
| Vitamin | Key role | Food sources | Deficiency disease |
|---|---|---|---|
| A | Vision (especially at night), skin health | Carrot, papaya, egg, milk | Night blindness |
| B₁ (Thiamine) | Nerve function, energy metabolism | Whole grains, legumes | Beriberi |
| B₂ (Riboflavin) | Energy production, skin | Milk, eggs, green veg | Cracked lips/skin |
| B₁₂ | Blood cell formation, nerve function | Meat, eggs, dairy | Anaemia |
| C (Ascorbic acid) | Immune system, collagen production | Amla, citrus, guava, capsicum | Scurvy (bleeding gums) |
| D | Calcium absorption; strong bones | Sunlight, fish, eggs | Rickets (children), Osteomalacia (adults) |
| K | Blood clotting | Green leafy vegetables | Poor clotting/bleeding |
Minerals in detail
| Mineral | Role | Sources | Deficiency |
|---|---|---|---|
| Calcium (Ca) | Bones, teeth, muscle contraction | Milk, cheese, ragi | Weak bones, rickets |
| Iron (Fe) | Haemoglobin in red blood cells | Spinach, meat, lentils | Anaemia (fatigue, pale skin) |
| Iodine (I) | Thyroid hormone production | Iodised salt, seafood | Goitre (swollen thyroid) |
| Phosphorus (P) | Bones, teeth, energy (ATP) | Dairy, meat, nuts | Weak bones |
Balanced diet
A balanced diet contains all six nutrients in the right proportions to meet the body's needs.
Key principles:
- Eat a variety of foods from all food groups.
- Proportion: ~50–60% carbohydrates, ~10–15% proteins, ~20–30% fats (with most from healthy sources).
- Choose whole foods over processed.
- Adequate water (6–8 glasses/day).
- Sufficient roughage (25–30 g/day for adults).
Factors affecting dietary needs:
- Age (children need more calcium and protein for growth).
- Activity level (athletes need more carbohydrates and proteins).
- Health status (pregnant women need more iron and calcium).
Deficiency diseases summary
| Disease | Nutrient missing | Symptoms |
|---|---|---|
| Scurvy | Vitamin C | Bleeding gums, loose teeth, slow wound healing |
| Rickets | Vitamin D / Calcium | Soft, bent bones in children |
| Beriberi | Vitamin B₁ | Weakness, nerve damage, fluid retention |
| Night blindness | Vitamin A | Can't see in dim light |
| Goitre | Iodine | Enlarged thyroid gland (neck swelling) |
| Anaemia | Iron / B₁₂ | Fatigue, pale skin, breathlessness |
| Kwashiorkor | Protein (severe) | Swollen belly, growth stunting |
| Marasmus | Calories + protein | Extreme wasting, very low body weight |
Testing for nutrients (food tests)
| Test | Nutrient detected | Result if present |
|---|---|---|
| Iodine test | Starch (carbohydrate) | Blue-black colour |
| Biuret test | Protein | Violet/purple colour |
| Paper spot test | Fat | Translucent (oily) patch on paper |
| Benedict's test | Reducing sugars (glucose) | Brick-red precipitate |
| Vitamin C test | Vitamin C | Decolourises DCPIP solution |
Quick check
- Name the six major nutrients. Which one is NOT actually digested but is still important?
- What disease is caused by lack of Vitamin C? What are its symptoms?
- What is a balanced diet? Name two factors that affect a person's dietary needs.
- Why is iron important? What disease results from iron deficiency?
- Which food test detects starch? What colour change occurs?
Open the Practice tab for graded questions on Food Components.
3 topics • Notes • Practice • AI explanations available
1. Nutrients
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2. Balanced Diet
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3. Deficiency
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