What Are Food Components?
Every time we eat a roti, dal, or banana, we’re actually consuming a mix of different nutrients — chemicals that our body uses for energy, growth, and staying healthy. These nutrients are the building blocks of food, and understanding them is the foundation of everything you’ll study in biology for the next several years.
The big idea: different foods contain different nutrients, and our body needs all of them to function properly. A mango and a piece of chicken look completely different, but both contain nutrients our body needs — just different ones in different amounts.
Class 6 NCERT covers six main components: carbohydrates, fats, proteins, vitamins, minerals, and water. Roughage is the seventh, though it’s not technically a nutrient in the traditional sense.
Key Terms and Definitions
Nutrients — Substances in food that our body uses for energy, building materials, and regulating body functions. Not everything we eat is a nutrient (roughage, for example, has no nutritional value but is still essential).
Carbohydrates — The primary energy source for the body. Made of carbon, hydrogen, and oxygen. Found in rice, wheat, potatoes, sugar, and fruits. Starch and sugar are both carbohydrates.
Fats — A concentrated energy source — fats give more than twice the energy per gram compared to carbohydrates. Found in ghee, butter, oil, nuts, and meat. Also called lipids.
Proteins — The building and repair materials of the body. Made of amino acids. Found in dal, eggs, milk, meat, and soybean. Called body-building foods.
Vitamins — Substances needed in tiny amounts for specific functions — keeping eyes healthy, clotting blood, protecting from infections. There are many types (A, B, C, D, E, K), each with a distinct job.
Minerals — Inorganic elements like calcium, iron, and iodine. Like vitamins, needed in small amounts but critical for specific functions.
Roughage (Dietary Fibre) — The indigestible part of plant foods (cellulose). Doesn’t provide nutrients but helps the digestive system move food along and prevents constipation.
Water — Makes up about 70% of the human body. Every chemical reaction inside us happens in water. We lose water through sweat, urine, and breath — so constant replenishment is necessary.
The Main Food Components — Explained
Carbohydrates
Carbohydrates are divided into two types:
- Simple carbohydrates (sugars): glucose, fructose, sucrose — found in fruits, honey, table sugar. These digest quickly and give instant energy.
- Complex carbohydrates (starch): found in rice, wheat, potatoes. These take longer to digest and provide sustained energy.
Why do athletes eat a lot of rice and pasta before a competition? Because carbohydrates are the fastest fuel source the body can use.
The starch test in Class 6 practical: add 2–3 drops of iodine solution to a food sample. If it turns blue-black, starch is present. If it stays brown-orange, no starch. This test is frequently asked in CBSE practicals.
Proteins
Think of proteins as the bricks and cement of your body. Every muscle fibre, every enzyme, every antibody is made of protein. When you get a cut, proteins repair the tissue. When you exercise, proteins rebuild stronger muscle fibres.
Protein-rich foods: Eggs, milk, cheese, paneer, dal, rajma, chana, soybean, fish, chicken.
The protein test in the lab uses copper sulphate solution and caustic soda (sodium hydroxide). A violet/purple colour confirms protein. This is called the Biuret test — you’ll formally study it in Class 10 and 12, but knowing the name now is a bonus.
Fats
Fats are the body’s energy reserve. When carbohydrates run out — for example, during a long fast — the body starts burning fat for energy.
Fats are also needed to absorb fat-soluble vitamins (A, D, E, K). This is why eating a completely fat-free diet is actually harmful — those vitamins simply won’t get absorbed no matter how much spinach or carrot you eat.
Fat-rich foods: Ghee, butter, cooking oil, nuts, seeds, fatty fish, meat.
The fat test in Class 6: rub a food sample on a piece of paper. Hold it against light. If you see a greasy translucent patch, fat is present. This is the simplest test in the syllabus — easy marks in practicals.
Vitamins
Vitamins are grouped into two categories based on how they dissolve:
| Vitamin | Main Function | Deficiency Disease | Source |
|---|---|---|---|
| A | Vision, skin health | Night blindness | Carrot, papaya, milk |
| B (complex) | Energy metabolism, nerves | Beriberi (B1), Anaemia (B12) | Whole grains, eggs |
| C | Immunity, wound healing | Scurvy | Amla, citrus fruits |
| D | Calcium absorption, bones | Rickets | Sunlight, fish liver oil |
| K | Blood clotting | Excessive bleeding | Green leafy vegetables |
CBSE marking pattern: Deficiency diseases are high-scoring one-mark questions. The five most tested pairs: Vitamin A → Night blindness, Vitamin B1 → Beriberi, Vitamin C → Scurvy, Vitamin D → Rickets, Vitamin C → Scurvy. Learn all five cold.
Minerals
Calcium — builds bones and teeth. Found in milk, curd, ragi. Deficiency causes weak bones.
Iron — part of haemoglobin in red blood cells. Found in spinach, jaggery, liver. Deficiency causes anaemia — you feel tired because blood can’t carry enough oxygen.
Iodine — needed for the thyroid gland to work properly. Found in iodised salt, seafood. Deficiency causes goitre — swelling of the thyroid gland in the neck.
Goitre due to iodine deficiency is a CBSE Class 6 standard question. Many students write “iodised salt prevents goitre” — correct, but the complete answer should explain why: the thyroid gland needs iodine to produce thyroxine hormone, and iodised salt provides this iodine.
Water
The functions of water in the body:
- Dissolves nutrients so they can be absorbed
- Carries nutrients to cells through blood (blood is mostly water)
- Removes waste products through urine and sweat
- Regulates body temperature through sweating
A person can survive weeks without food but only a few days without water. This tells you how critical water is.
Roughage
Roughage (dietary fibre) comes from plant cell walls — primarily cellulose. Our body cannot digest it, but it:
- Absorbs water and adds bulk to stool
- Stimulates the walls of the intestine to push food along (peristalsis)
- Prevents constipation
Sources: whole grain flour (atta vs. maida), vegetables, fruits with skins, oats, pulses.
Students often say roughage is a “nutrient.” Technically, it is not a nutrient because the body doesn’t digest or absorb it. It’s a component of food, but not a nutrient. Write this carefully in exams.
Balanced Diet
A balanced diet contains all nutrients in the right proportions — not too much of any one thing, and not too little of another.
The key idea: no single food is “complete” on its own. Rice gives carbohydrates but almost no protein. Dal gives protein but little fat. Milk gives protein, fat, calcium, and Vitamin D — making it one of the most complete foods, but even milk lacks Vitamin C and iron.
This is why we eat a variety of foods. A meal of rice + dal + sabzi + curd is a classic balanced combination covering carbohydrates, protein, fat, vitamins, and minerals together.
Carbohydrates (energy) + Proteins (building) + Fats (energy reserve) + Vitamins (regulation) + Minerals (regulation) + Water + Roughage = Balanced Diet
Solved Examples
Example 1 — Easy (CBSE Class 6)
Q: Name two foods rich in Vitamin C and state what happens if we don’t get enough Vitamin C.
Solution: Foods rich in Vitamin C: Amla (Indian gooseberry) and lemon (or orange, guava — any citrus fruit is acceptable).
Deficiency of Vitamin C causes scurvy — a disease where gums bleed, teeth become loose, and wounds heal slowly.
Example 2 — Easy (CBSE Class 6)
Q: Rajesh eats only white rice and refined flour (maida) products. What nutrient is he likely missing and what problem might this cause?
Solution: Rajesh is missing roughage (dietary fibre) because white rice and maida are processed foods with the outer fibre-rich bran removed.
The likely problem: constipation — difficulty passing stools because there’s no fibre to add bulk and stimulate intestinal movement.
Example 3 — Medium (CBSE Class 6)
Q: A doctor notices a child has bowed legs and a curved spine. The child lives indoors most of the time and eats very little fish or dairy. Which vitamin is deficient? How would you treat this?
Solution: The symptoms — bowed legs and curved spine in a child — point to rickets, caused by Vitamin D deficiency.
Vitamin D is needed for the body to absorb calcium. Without enough Vitamin D, bones don’t harden properly and bend under body weight.
Treatment: exposure to sunlight (the body makes Vitamin D when skin absorbs UV rays) and including fish liver oil, eggs, and milk in the diet.
Sunlight is free and one of the best sources of Vitamin D — which is why rickets used to be rare in India despite dietary gaps. As children spend more time indoors (phones, AC rooms), Vitamin D deficiency is increasing even in sunny India.
Example 4 — Medium (CBSE Class 6)
Q: Perform the iodine test on the following foods and predict the result: (a) potato (b) sugar (c) cooked rice (d) raw carrot
Solution:
| Food | Contains starch? | Iodine test result |
|---|---|---|
| Potato | Yes | Blue-black |
| Sugar | No (it’s sucrose, a simple carbohydrate, not starch) | Brown-orange (no change) |
| Cooked rice | Yes | Blue-black |
| Raw carrot | Trace amounts | Faint blue, mostly unchanged |
Common mistake here: students assume all carbohydrates will turn blue-black with iodine. Only starch does this. Sugar does not — the iodine test is specifically a starch test, not a general carbohydrate test.
Exam-Specific Tips
CBSE Class 6 Board Pattern
- This chapter carries 8–12 marks in the Class 6 annual exam — one of the heavier chapters.
- Questions are typically: one-mark (name/define), two-mark (state two functions/give two examples), three-mark (compare/give deficiency diseases table), and five-mark (explain balanced diet with examples).
- The practical component — iodine test, fat test, protein test — is often part of the Term 2 assessment or activity-based questions.
Memorise this table completely for CBSE:
| Nutrient | Function | Source | Deficiency |
|---|---|---|---|
| Carbohydrate | Energy | Rice, wheat | Fatigue |
| Protein | Growth & repair | Dal, egg | Kwashiorkor, Marasmus |
| Fat | Energy reserve | Ghee, oil | Poor vitamin absorption |
| Vitamin A | Vision | Carrot | Night blindness |
| Vitamin C | Immunity | Amla | Scurvy |
| Vitamin D | Bone strength | Sunlight | Rickets |
| Iron | Blood | Spinach | Anaemia |
| Iodine | Thyroid | Iodised salt | Goitre |
For Students Aiming Ahead (Class 9-10 Preparation)
The food components chapter connects directly to Class 9 Chapter “Why Do We Fall Ill?” (where nutrition links to health) and Class 10 “Life Processes” (digestion, absorption). Building a strong foundation now means less rote learning later.
Common Mistakes to Avoid
Mistake 1: Confusing roughage with a nutrient. Roughage is not a nutrient — it cannot be digested or absorbed. It’s a food component, but writing “roughage is a nutrient” will cost you marks.
Mistake 2: Thinking Vitamin D comes only from food. Vitamin D is unique — our skin manufactures it when exposed to sunlight. Food sources exist (fish liver oil, egg yolk), but sunlight is the primary source. Many students write only food sources and miss the sunlight point.
Mistake 3: Saying iodine turns blue-black with any carbohydrate. The iodine test detects starch specifically. Sugar (glucose, fructose, sucrose) does not give a blue-black result. Test answer: “Iodine solution turns blue-black in the presence of starch.”
Mistake 4: Confusing Kwashiorkor and Marasmus. Both are protein deficiency diseases, but they’re different:
- Kwashiorkor: protein deficiency with adequate calorie intake → swollen belly, puffy face
- Marasmus: both protein and calorie deficiency → extremely thin, wasted muscles
In Class 6, knowing both names exists is enough. Class 9 requires more detail.
Mistake 5: Writing “balanced diet means equal amounts of all nutrients.” A balanced diet means the right proportions — carbohydrates should be the largest component, proteins and fats moderate, vitamins and minerals in small amounts. “Equal amounts” is incorrect and will be marked wrong.
Practice Questions
Q1. Name the nutrient that gives the most energy per gram — fat or carbohydrate?
Fat. Fat provides approximately 9 kcal per gram, while carbohydrates provide about 4 kcal per gram. This is why fats are described as a “concentrated” or “high-energy” source.
Q2. Why should we use iodised salt instead of plain salt?
Iodised salt contains added iodine. Iodine is needed by the thyroid gland to produce the hormone thyroxine. Without iodine, the thyroid gland enlarges to try to absorb more iodine from the blood, causing a visible swelling in the neck called goitre. Using iodised salt prevents goitre.
Q3. Sunita eats plenty of spinach (palak) every day but her doctor says she is anaemic. What mineral might she still be lacking, and why might spinach not be enough?
Sunita is likely deficient in iron. Spinach does contain iron, but it also contains oxalic acid, which reduces iron absorption in the body. Additionally, plant-based iron (non-haeme iron) is absorbed less efficiently than the iron from animal sources like meat and liver. The doctor might also recommend eating spinach with Vitamin C (like lemon juice), which significantly improves iron absorption.
(Note: This level of detail goes beyond Class 6 NCERT but is good for curious students.)
Q4. Which of these meals is more balanced — (a) a plate of only white rice, or (b) a plate of rice + dal + cucumber slices? Explain why.
Meal (b) — rice + dal + cucumber slices — is more balanced.
- Rice provides carbohydrates (energy)
- Dal provides protein (body-building) and some B vitamins
- Cucumber provides water, roughage, and some minerals
Meal (a) provides only carbohydrates and virtually no protein, vitamins, minerals, or roughage. The body cannot build and repair itself without protein, and digestion suffers without roughage.
Q5. A child’s gums are swollen and bleeding. She gets tired easily and takes a long time to recover from small cuts. Which vitamin is deficient?
Vitamin C deficiency. The disease is called Scurvy.
Vitamin C is needed for:
- Making collagen — the protein that holds gum tissue and skin together
- Wound healing
- Immune function
Sources to include: amla, lemon, orange, guava, tomato.
Q6. Do fats serve any purpose other than providing energy? Name two.
Yes, fats serve several roles beyond energy storage:
- Absorbing fat-soluble vitamins: Vitamins A, D, E, and K can only be absorbed from the digestive system in the presence of fat. No dietary fat = these vitamins pass through unabsorbed.
- Insulation: Fat deposits under the skin (subcutaneous fat) keep the body warm in cold conditions.
- Protecting organs: Fat cushions internal organs like the kidneys and heart from physical shocks.
Q7. Why do we need roughage if it provides no nutrients?
Roughage (dietary fibre) is essential even though it provides no nutrients because:
- It adds bulk to stool, making it easier to pass through the intestine
- It stimulates the intestinal walls to contract (peristalsis), keeping food moving
- It prevents constipation and related problems like piles
Think of roughage as a broom for the digestive system — it doesn’t feed us, but it keeps the system clean and functioning.
Q8. Your friend says, “I drink a lot of milk, so I don’t need to eat anything else.” Is your friend right? What nutrients would they be missing?
Your friend is wrong. Milk is one of the most complete foods available — it contains protein, fat, carbohydrates, calcium, Vitamin D, and B vitamins. But it is significantly low in:
- Vitamin C (milk has almost none)
- Iron (very little iron in milk)
- Dietary roughage (milk has no fibre)
- Vitamin K
A person living only on milk would eventually develop scurvy (Vitamin C deficiency) and anaemia (iron deficiency). No single food can be a complete diet.
FAQs
What are the 7 components of food?
The seven components of food are: carbohydrates, fats, proteins, vitamins, minerals, water, and roughage (dietary fibre). Of these, the first six are considered nutrients — roughage is essential but not technically a nutrient since the body doesn’t absorb it.
What is the difference between vitamins and minerals?
Vitamins are organic compounds — they contain carbon and are made by living organisms (plants, animals, bacteria). Minerals are inorganic — they are elements from the earth (calcium, iron, iodine) and cannot be made by living organisms. Both are needed in small amounts and both regulate body processes.
Which food gives the most energy?
Fats give the most energy per gram (approximately 9 kcal/g). For a meal-based answer: foods rich in fat and carbohydrates like ghee-fried parathas, nuts, or full-fat dairy give the most energy per serving. However, for sustained, clean energy, complex carbohydrates (whole grains) are preferred over pure fats.
Is water a nutrient?
Yes, water is classified as a nutrient. It’s needed for every biochemical reaction in the body, for transporting nutrients, for regulating temperature, and for removing waste. Without water, the body cannot use any of the other nutrients effectively.
What happens if we eat too much protein?
The body cannot store excess protein the way it stores fat. Extra protein is broken down, and the nitrogen is excreted through urine (as urea). This puts extra load on the kidneys. Long-term very high protein intake can stress the kidneys — relevant for people taking high-protein supplements without need.
Which vitamin does sunlight give us?
Sunlight triggers the synthesis of Vitamin D in the skin. Specifically, UV-B radiation from sunlight converts a cholesterol compound in the skin into Vitamin D3. This is why Vitamin D is sometimes called the “sunshine vitamin.” About 15-20 minutes of sunlight exposure on the arms and face (without sunscreen) is enough to meet daily Vitamin D needs in most people.
What is the difference between Kwashiorkor and Marasmus?
Both are diseases caused by malnutrition:
- Kwashiorkor: caused by severe protein deficiency, even when total calories may be adequate. Symptoms include swollen belly (pot belly), puffy face, and thin limbs.
- Marasmus: caused by deficiency of both protein and calories. The child appears extremely thin with no muscle or fat tissue, often described as “skin and bones.”
Marasmus is more severe overall as the body has no energy reserves at all.
Why do we get tired when we don’t eat for a long time?
When we don’t eat, blood glucose levels fall. Since glucose (from carbohydrates) is the brain’s primary fuel, low glucose makes us feel mentally foggy and physically weak. After extended fasting, the body begins breaking down fat and then muscle protein for energy — which is why long-term starvation causes both fat loss and muscle wasting.