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examBoard: Pearson Edexcel
examType: IGCSE
lessonTitle: Balanced Diet Components
A balanced diet contains all the nutrients our bodies need in the right proportions to stay healthy. Think of your body as a complex machine that needs the right fuel and building materials to work properly. Without these nutrients, various body systems can break down, leading to health problems.
Key Definitions:
Carbohydrates are your body's main energy source. They break down into glucose, which fuels your brain, muscles and other organs.
Sources: Bread, pasta, rice, potatoes, cereals, fruits
Types:
About 50-55% of your daily calories should come from carbohydrates, mainly complex ones.
Proteins are the building blocks of your body. They're essential for growth, repair and making enzymes and hormones.
Sources: Meat, fish, eggs, dairy, beans, lentils, nuts
Proteins are made of amino acids. Some are 'essential' - your body can't make them, so you must get them from food.
About 15-20% of your daily calories should come from protein sources.
Fun fact: Your hair and nails are mostly made of a protein called keratin!
Fats often get a bad reputation, but they're vital for your body. They provide energy, insulation, protection for organs and help absorb certain vitamins.
Sources: Oils, butter, cheese, fatty meats, avocados, nuts
Types:
About 30% of your daily calories should come from fats, mostly unsaturated.
Fibre is a type of carbohydrate that your body can't digest. It passes through your digestive system, helping everything move along smoothly.
Sources: Whole grains, fruits, vegetables, beans, nuts
Benefits:
Adults should aim for about 30g of fibre daily.
While you need macronutrients (carbs, proteins, fats) in large amounts, micronutrients are needed in smaller quantities but are just as important for health.
Role: Helps wound healing, immune function and acts as an antioxidant
Sources: Citrus fruits, berries, peppers, broccoli
Deficiency: Scurvy (bleeding gums, poor wound healing)
Role: Helps absorb calcium for strong bones and teeth
Sources: Sunlight on skin, oily fish, eggs, fortified foods
Deficiency: Rickets in children, osteomalacia in adults
Role: Important for vision, immune function and skin health
Sources: Liver, dairy, orange/yellow vegetables, leafy greens
Deficiency: Night blindness, increased infections
Role: Builds strong bones and teeth, helps muscles contract
Sources: Dairy products, leafy greens, fortified plant milks
Deficiency: Weak bones, osteoporosis later in life
Role: Helps red blood cells carry oxygen around the body
Sources: Red meat, beans, lentils, leafy greens, fortified cereals
Deficiency: Anaemia (tiredness, weakness, pale skin)
Role: Maintains fluid balance, helps nerve and muscle function
Sources: Table salt, processed foods, natural foods in small amounts
Note: Most people consume too much sodium, which can lead to high blood pressure
Water makes up about 60% of your body and is essential for nearly every bodily function. It:
You should aim to drink 6-8 glasses of fluid daily. Water is best, but tea, coffee, milk and juice all contribute to your fluid intake. Remember, you also get water from foods, especially fruits and vegetables.
Dehydration signs: Thirst, dark urine, headaches, tiredness, dry mouth
In the 1700s, scurvy killed more British sailors than enemy action! Symptoms included bleeding gums, reopening of old wounds and eventually death. In 1747, ship's surgeon James Lind conducted one of the first clinical trials. He gave different treatments to sailors with scurvy and found that those who ate citrus fruits recovered quickly.
This led to British sailors being given lime juice on long voyages (earning them the nickname "limeys"). We now know scurvy is caused by vitamin C deficiency. This historical example shows how important a balanced diet with all necessary nutrients is for health.
A simple way to achieve a balanced diet is to follow the Eatwell Guide, which shows the proportions of different food groups you should eat:
Ask yourself these questions to see if your diet is balanced:
If you answered "no" to any of these, you might need to adjust your diet for better balance.
Nutritional needs change throughout life:
Remember, a balanced diet isn't about perfection or strict rules. It's about making healthy choices most of the time, while still enjoying occasional treats. Small, sustainable changes to your eating habits can make a big difference to your health over time.
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