3.2. Describe nutrients needed by the body

This guide will help you answer 3.2. Describe nutrients needed by the body.

The human body needs a wide range of nutrients to work well. Nutrients are substances found in food and drink. They help the body grow, stay healthy, and do everyday tasks. Some nutrients provide energy, some build and repair tissues, and others support important chemical reactions.

These nutrients fall into groups. There are macronutrients, which the body needs in larger amounts, and micronutrients, needed in smaller amounts. Water is another important nutrient group. In this guide, we will cover these groups and about individual nutrients within them.

Macronutrients

Macronutrients are nutrients we need in significant amounts. They provide energy or help the body use energy. There are three main macronutrients:

Carbohydrates
Proteins
Fats

Each group plays a specific role. Let’s look more closely at each one.

Carbohydrates

Carbohydrates are the main source of energy for most people. The body breaks them down into glucose (a type of sugar), which is used for fuel. Glucose powers the brain, muscles, and many organs.

Sources of carbohydrates include:

Bread
Rice
Pasta
Potatoes
Fruit
Vegetables

Carbohydrates can be sorted into two types:

Simple carbohydrates: Found in sugar, sweets, and fruit. They are broken down quickly and used for fast energy.
Complex carbohydrates: Found in foods like whole grains and vegetables. They take longer to break down and provide lasting energy.

The body uses carbohydrate energy first before looking for other fuel. Not eating enough carbohydrates can leave a person feeling weak or tired.

Proteins

Proteins build, repair, and maintain body tissues. Muscles, organs, skin, and even blood contain proteins. Proteins are made of smaller parts called amino acids.

The body needs twenty different amino acids. Twelve can be made by the body, but eight must come from food. These are called essential amino acids.

Good sources of protein are:

Meat and fish
Eggs
Dairy products such as milk, cheese, and yoghurt
Beans, lentils, and peas
Nuts and seeds

Protein is not only about muscle. It is part of every cell in the body. It helps make enzymes (which support chemical reactions), hormones, and a strong immune system.

Fats

Fats are another source of energy. They are more dense than carbohydrates, giving more calories per gram. Fats help absorb vitamins, protect organs, and keep the body warm.

There are a few main types of fats:

Saturated fats: Found in animal products, such as butter, cheese, and fatty meat. Eating too much can raise cholesterol, which can harm heart health.
Unsaturated fats: Found in plant oils, nuts, seeds, and oily fish. These support heart health when eaten instead of saturated fats.
Trans fats: These are often found in processed foods. They are made by changing the structure of oils and are considered harmful.

The body uses fat for energy when carbohydrates are low. It is important not to eat too much or too little fat in the diet.

Micronutrients

Micronutrients are vitamins and minerals. These are needed in small amounts but play important roles in the body.

Without enough micronutrients, a person can develop health problems over time. Let’s look at the main groups.

Vitamins

Vitamins are chemicals that help the body carry out everyday processes. There are two types:

Fat-soluble vitamins (A, D, E, K): These dissolve in fat and are stored in body tissue.
Water-soluble vitamins (B group and C): These dissolve in water and are not stored for long.

Vitamin A

Helps vision, skin health, and the immune system.
Found in liver, oily fish, eggs, dairy, and colourful fruits and vegetables.

B Vitamins

The B vitamin group includes B1 (thiamine), B2 (riboflavin), B3 (niacin), B6, B12, folic acid and others. Each B vitamin supports different body systems.

Help release energy from food
Support the nervous system and red blood cell production
Found in whole grains, meat, eggs, dairy, green veg, and beans

Vitamin C

Supports the immune system, helps wounds heal, and keeps skin and vessels healthy.
Found in citrus fruit, berries, peppers, tomatoes, and broccoli.

Vitamin D

Keeps bones, teeth, and muscles strong by helping the body use calcium.
Made in the skin from sunlight, and found in oily fish, eggs, fortified foods.

Vitamin E

Protects cell membranes from damage.
Found in vegetable oils, nuts, seeds, and green leafy vegetables.

Vitamin K

Helps blood clot and keeps bones healthy.
Found in green leafy vegetables, such as spinach and kale, and in smaller amounts in other foods.

Minerals

Minerals are solid natural substances in food that help the body do many jobs.

Calcium

Builds and keeps bones and teeth strong.
Needed for muscle movement and nerve signals.
Found in milk, cheese, yoghurt, green leafy veg, and nuts.

Iron

Makes haemoglobin, the part of red blood cells that carries oxygen.
A lack of iron causes tiredness and may lead to anaemia.
Found in red meat, pulses, fortified cereals, spinach.

Potassium

Helps control fluid balance, muscle contractions, and nerve signals.
Found in bananas, potatoes, beans, fish, and dairy.

Sodium

Regulates water levels and blood pressure.
Found in salt. Too much can raise blood pressure.

Magnesium

Needed for muscle and nerve function, and to make energy.
Found in nuts, seeds, whole grains, and green vegetables.

Zinc

Helps the immune system and heals wounds.
Found in meat, dairy, bread, and cereal.

Iodine

Needed to make thyroid hormones, which control the body’s metabolism.
Found in dairy and seafood.

Water

Water is an often overlooked nutrient, but it is just as important as any other. The body is made up of over half water. Every cell, tissue, and organ needs water to work.

Water has many uses:

Helps control body temperature through sweating
Moves nutrients around the body
Removes waste through urine
Supports digestion and keeps skin healthy

Signs of not enough water include thirst, dry mouth, headache, and tiredness. Adults should aim to drink 1.5 to 2 litres a day, more in hot weather or if active.

Fibre

Fibre is a part of plant food that the body cannot fully digest. It does not count as a nutrient in the strictest biochemical sense, but it is important for good digestion and health.

Sources of fibre:

Wholemeal bread and pasta
Brown rice
Fruits and vegetables
Beans and lentils

Eating enough fibre keeps the digestive system regular, lowers cholesterol, and can help with weight control.

Phytochemicals and Other Nutritional Compounds

Phytochemicals are natural compounds in plant foods. They are not essential for health but appear to help prevent disease and keep people feeling well.

Some well-known phytochemicals are:

Flavonoids (in fruit, veg, tea, and chocolate)
Carotenoids (in carrots, sweet potatoes, spinach)
Polyphenols (in berries, olives, nuts)

These protect cells from damage. They are believed to support the immune system and may lower the risk of illness.

Nutrient Needs at Different Life Stages

Nutrient needs change at different points in life. For example:

Babies need more fat for brain growth.
Children and teenagers require extra protein, calcium, and iron as they grow.
Pregnant and breastfeeding women need more of many nutrients to support their baby’s development.
Older adults may need more vitamin D and calcium to keep bones strong.

It is important to adjust the diet at different ages to meet changing body needs.

Nutrient Interactions and Balance

The body needs many nutrients work together. For example, vitamin C helps the body absorb iron from plants. Too much of one nutrient can sometimes cause problems with another. A balanced diet, with a variety of foods, will usually provide what the body needs.

Getting nutrients from food, not supplements, is safest for most people. The body absorbs and uses nutrients from food better than those from pills.

Deficiency and Excess

When the body does not get enough of a nutrient, it is called a deficiency. This can cause:

Tiredness (lack of iron)
Weak bones (lack of calcium or vitamin D)
Poor growth (lack of protein or other nutrients)
Trouble fighting illness (lack of zinc or vitamins)

On the other hand, too much of a nutrient can harm health. For example:

Too much fat or sugar can cause weight gain and illness.
Too much salt can raise blood pressure.
Too much vitamin A can damage the liver.

There is a recommended amount for each nutrient, called the Reference Nutrient Intake (RNI), to help people know how much they need.

Meeting Nutrient Needs Through Diet

The best way to get nutrients is by eating a balanced diet. This includes:

Starchy carbohydrates (about a third of the diet)
Plenty of fruit and vegetables (at least five portions a day)
Moderate amounts of protein foods
Some dairy or alternatives
A small amount of fats and oils
Not too much sugar, salt, or processed food

People with special diets, like vegans or those with allergies, may need to plan more carefully to get all nutrients.

How Food Labels Help

Food labels show the amounts of energy (kilojoules/kilocalories), protein, carbohydrates, fats, fibre, vitamins, and minerals in food. These labels help people check if they are getting enough of each nutrient.

Reading labels can also help people avoid too much fat, sugar, or salt.

Final Thoughts

Nutrients are the foundation of good health. The body needs a balance of macronutrients (carbohydrates, proteins, and fats), micronutrients (vitamins and minerals), water, and fibre to work properly. Each nutrient has its own role, from powering the body and fighting illness, to keeping bones and muscles strong.

Striking the right balance between different nutrients keeps both the body and mind in good condition. A diet with a wide variety of foods, plenty of fruit and vegetables, whole grains, healthy fats, and enough protein is the most reliable way to get what the body needs.

Paying attention to how the body feels, reading food labels, and making small changes to food choices can go a long way to support better health. For most people, food should be the main source of nutrients, with supplements only used when there is a real need.

Remember, hunger, tiredness, poor concentration, or feeling unwell can be signs something is missing in the diet. If you suspect a nutrient problem, or if health conditions or special diets complicate things, ask for advice from a dietitian or doctor.

Giving the body everything it needs, in the right amounts, lays the groundwork for long, strong, and healthy living. Balancing nutrients does not have to be difficult when meals are varied, colourful, and enjoyed every day.