3.4 Describe the role of nutrients in maintaining health

This guide will help you answer 3.4 Describe the role of nutrients in maintaining health.

Nutrients are substances in food that the body needs for growth, energy, maintenance, and repair. Each nutrient has its own role and specific function. Eating the correct balance of nutrients keeps the body working well, supports the immune system, and helps prevent illness. Food is the body’s only source of these nutrients, so the diet has a big effect on health.

Carbohydrates

Carbohydrates are the main source of energy for the body. The body breaks down carbohydrates into glucose, which travels in the blood and is used by cells for energy. The brain and nervous system rely on glucose from carbohydrates.

There are two main types of carbohydrates:

• Simple carbohydrates – found in sugars, fruit, and sweets.
• Complex carbohydrates – found in bread, rice, pasta, potatoes, wholegrains, and cereals.

Complex carbohydrates provide longer-lasting energy. They usually contain more fibre, which benefits the digestive system.

Functions of carbohydrates include:

• Providing quick and steady energy.
• Supporting physical activity.
• Fuel for the brain, muscles, nerves, and other body systems.
• Sparing protein from being used for energy, so protein can focus on growth and repair.

Too few carbohydrates may lead to tiredness, low mood, and poor concentration. Eating too many sugary foods can cause tooth decay and weight gain.

Protein

Protein is made of amino acids, which are building blocks for the body. There are twenty amino acids in total. Nine of these are essential, meaning the body cannot make them and must get them from food.

Main sources of protein include:

• Meat, fish, eggs, dairy products.
• Beans, pulses, nuts, seeds, tofu, and some grains.

Protein is used to:

• Build and repair tissues, such as muscles, skin, and organs.
• Help produce enzymes and hormones.
• Support the immune system.
• Provide energy if other sources are not available.

Growth in children, teenagers, and pregnant women depends on enough protein.

A lack of protein may cause muscle wasting, poor wound healing, and a weaker immune system. Some people, such as athletes or pregnant women, may need more protein.

Fat

Fat is a concentrated source of energy. It helps the body absorb certain vitamins and forms part of every cell.

Types of fats:

• Saturated fat – found in animal products like meat, butter, and cheese.
• Unsaturated fat – found in plant oils, nuts, seeds, oily fish, and avocados.
• Trans fats – found in some processed foods like biscuits and cakes.

Functions of fat include:

• Providing energy storage.
• Cushioning organs to protect them from injury.
• Insulating the body against the cold.
• Transporting and absorbing fat-soluble vitamins (A, D, E, K).
• Producing hormones.

Eating too much saturated and trans fat can lead to raised cholesterol, which is linked with heart disease. Replacing saturated fat with unsaturated fat can lower cholesterol and support heart health. Some fats, such as omega-3 and omega-6 fatty acids, are called “essential fats” because the body cannot make them.

Vitamins

Vitamins are chemical compounds needed in small amounts. They help thousands of body processes run smoothly. Each vitamin has a different role.

Main groups:

• Fat-soluble vitamins (A, D, E, K) – stored in the body’s fatty tissue.
• Water-soluble vitamins (B group and vitamin C) – not stored, so regular intake is needed.

Vitamin A

• Found in: liver, dairy, eggs, carrots, green leafy vegetables.
• Helps: maintain good vision, skin health, immune system, and growth.

B Vitamins (e.g., B1, B2, B3, B6, B12, Folate)

• Found in: wholegrains, meat, dairy, green vegetables, eggs, beans.
• Help: release energy from food, support the nervous system, make red blood cells.

Vitamin C

• Found in: citrus fruits, strawberries, peppers, tomatoes, potatoes.
• Helps: absorb iron, heal wounds, boost the immune system, keep skin and gums healthy.

Vitamin D

• Found in: oily fish, eggs, fortified foods, sunlight on skin.
• Helps: absorb calcium, keep bones and teeth strong, support immune system.

Vitamin E

• Found in: vegetable oils, nuts, seeds, green leafy vegetables.
• Acts as an antioxidant to help protect cells from damage.

Vitamin K

• Found in: green leafy vegetables, dairy, liver, vegetable oils.
• Helps blood clot and support bone health.

Lack of specific vitamins has different results, such as scurvy (vitamin C), rickets (vitamin D), or anaemia (vitamin B12, folate).

Minerals

Minerals are chemical elements needed for many processes in the body. They are present in food in small amounts but have big effects on health.

Iron

• Found in: red meat, beans, lentils, nuts, green vegetables, fortified cereals.
• Used to: make haemoglobin (carries oxygen in red blood cells).
• Low iron can cause tiredness, weakness, and anaemia.

Calcium

• Found in: dairy products, tofu, green vegetables, nuts, seeds, fortified bread.
• Supports: strong bones and teeth, muscles and nerves.

Potassium

• Found in: bananas, potatoes, avocados, pulses, tomatoes.
• Important for: blood pressure control, nerve signals, and muscle function.

Zinc

• Found in: meat, fish, dairy, nuts, wholegrains, pulses.
• Needed for: immune function, wound healing, DNA production.

Iodine

• Found in: dairy products, fish, eggs, seaweed.
• Helps: make thyroid hormones to control metabolism and growth.

Sodium

• Mainly from: table salt, processed foods.
• Needed for: controlling body fluids, nerve and muscle function.

The right amount of minerals is important. Too much or too little affects health. For example, high sodium intake can raise blood pressure.

Fibre

Fibre (sometimes called roughage) is the part of plant food that the body cannot digest. There are two types:

• Soluble fibre – dissolves in water. Found in oats, beans, and lentils. Helps lower cholesterol.
• Insoluble fibre – does not dissolve in water. Found in wholegrains, nuts, seeds, skin of fruit and vegetables. Helps keep bowels regular.

Main functions:

• Keeps the digestive system healthy.
• Prevents constipation.
• Helps keep cholesterol in check.
• Aids in blood sugar control.

Many people do not get enough fibre. Low fibre increases the risk of constipation, bowel disease, and heart disease.

Water

Water is the main component of the human body, making up about two-thirds of body weight. Every system depends on water.

Main roles of water:

• Regulates body temperature (through sweating and breathing).
• Removes waste (through urine and faeces).
• Transports nutrients around the body in blood and other fluids.
• Cushions and protects joints.
• Helps with digestion.

Not drinking enough causes dehydration, which leads to tiredness, headaches, dizziness, and confusion. The body loses water all the time through breathing, sweating, and urination, so fresh intake is needed daily.

The Role of Nutrients in Specific Health Areas

Growth and Development

Children and teenagers need enough protein, vitamins, minerals, and energy for healthy growth. Lack of these nutrients delays development, affects learning, and weakens bones and teeth.

Pregnant women need more iron, calcium, folate, and other nutrients to support the growing baby. Folate prevents birth defects in the brain and spine.

Immune System Support

Protein, vitamins A, C, D, and minerals such as zinc and iron keep the immune system ready to fight infections. Poor nutrition makes it easier to catch colds, flu, and other illnesses.

Bone Health

Calcium and vitamin D are key for strong bones. Lack of these nutrients can lead to brittle bones or osteoporosis later in life. Children, older adults, and pregnant women have higher needs for these nutrients.

Energy and Mental Health

Carbohydrates supply energy for muscles and the brain. Iron is needed for carrying oxygen in the blood. Low iron or low carbohydrate intake may cause tiredness and poor concentration.

Some vitamins and minerals help with brain and nerve function. B vitamins, vitamin C, omega-3 fats, and magnesium all play a part in mood, memory, and mental sharpness.

Preventing Long-term Disease

A balanced diet rich in nutrients can lower the risk of developing diseases, such as:

• Heart disease – linked with too much saturated fat, salt, or not enough fruit, vegetables, and fibre.
• Type 2 diabetes – linked with low fibre and high sugar diets.
• Cancer – fruit, vegetables, and fibre have a protective effect.
• Obesity – linked with excess energy, sugar, and fat.

Healthy Eating Patterns

Eating a wide variety of foods can help you get all the nutrients you need. The Eatwell Guide is a useful tool. It suggests:

• Plenty of fruit and vegetables.
• Wholegrain starchy foods such as bread, pasta, rice, potatoes.
• Some dairy or dairy alternatives.
• Some beans, pulses, fish, eggs, meat.
• Unsaturated oils and spreads in small amounts.
• Drink plenty of fluids.

Snack foods, sweets, and sugary drinks do not contribute good nutrition and may lead to weight gain or cavities if eaten too often.

Many people need to eat more fruit, vegetables, wholegrains, and oily fish. Watch out for large portion sizes, fatty and sugary foods, and salt intake.

Final Thoughts

Eating the correct mix of nutrients at every stage of life helps your body work at its best. Each nutrient’s role is unique, but they often depend on each other. For example, vitamin C helps the body use iron, while fat is needed to absorb certain vitamins.

No food contains all the nutrients you need, which is why variety matters. Many health problems start with poor nutrition, but small, regular changes to your diet can make a big positive difference. Eating well supports your immune system, helps growth and development, and keeps your organs, bones, muscles, and mind healthy.

In the end, a balanced diet gives your body what it needs to grow, heal, and feel good. Make choices that suit your individual lifestyle, taste, medical needs, and nutrition goals. If you have any health conditions or are unsure about eating plans, always speak to a registered dietitian or qualified health professional for advice. Your health is shaped by what you eat, and good nutrition lays the foundation for a full and active life.