Introduction to Diet, Nutrition and Health

Welcome! In this chapter, we are looking at the "big picture" of food. We’ve already learned about specific nutrients like proteins and vitamins, but now we are going to see how they all fit together to keep us healthy throughout our lives. Whether you are a toddler growing fast or an adult trying to stay fit, your body has different "rules" for what it needs. We will also explore how the choices we make now can prevent health problems like heart disease or diabetes later on.

1. Current Guidelines: The Eatwell Guide

To help people follow a healthy diet, the government uses the Eatwell Guide. Think of it as a giant plate that shows exactly how much of each food group you should eat to get a balanced diet.

The guide is split into five main sections:

1. Fruit and Vegetables: You should aim for at least 5 portions a day. These provide vital vitamins, minerals, and fibre.
2. Potatoes, Bread, Rice, Pasta, and Starchy Carbohydrates: This should make up about a third of what you eat. Choose whole grain versions for extra fibre.
3. Beans, Pulses, Fish, Eggs, Meat, and Other Proteins: These help the body grow and repair. The guide suggests eating more beans and pulses and at least two portions of fish a week.
4. Dairy and Alternatives: These are great sources of calcium for strong bones and teeth.
5. Oils and Spreads: We only need a very small amount of these, and they should be unsaturated fats (like vegetable oil).

Top Tip: Remember that "Free Sugars" (the sugar added to food and drinks) are not part of the main "plate"—they are shown off to the side to remind us to eat them less often and in small amounts!

2. Energy Needs: BMR and PAL

Energy is the "fuel" our body uses to keep us alive and moving. But how much do we actually need? It depends on two main things:

Basal Metabolic Rate (BMR)

Your BMR is the minimum amount of energy your body needs just to keep your heart beating and your lungs breathing while you are totally at rest. Factors that change your BMR include:

- Age: BMR is higher in children and teenagers because they are growing.
- Gender: Men generally have a higher BMR because they usually have more muscle mass.
- Body Size: Larger people often have a higher BMR.

Physical Activity Level (PAL)

Your PAL is a measure of how much extra energy you use through movement and exercise. If you sit at a desk all day, your PAL is low. If you are an athlete, your PAL is very high.

The total energy you need is calculated as:
\( \text{Total Energy Requirement} = \text{BMR} \times \text{PAL} \)

Where should our energy come from?

The official guidelines state our daily energy should be split like this:

- Protein: \( 15\% \)
- Fat: \( 35\% \) or less
- Carbohydrates: \( 50\% \) (mostly from starch, lactose, and fruit sugars; only a maximum of \( 5\% \) should come from free sugars).

3. Nutritional Needs Through Life Stages

Our bodies change as we get older, and so do our nutritional requirements. Don’t worry if this seems like a lot to remember—just think about what the body is doing at that age!

Young Children (1–4 years)

Because they are small but very active, they need energy-dense foods (lots of energy in small portions). They need plenty of calcium and Vitamin D for bone growth.

Teenagers

This is a time of rapid "growth spurts."
- Protein is vital for growing muscles.
- Calcium and Vitamin D are needed to reach "peak bone mass."
- Iron is especially important for girls once they start their periods to prevent anaemia.

Adults

Growth has stopped, so adults should focus on maintenance. The main goal is to balance energy intake with activity to avoid putting on too much weight.

The Elderly

As people get older, they often become less active, so they need less energy (fewer calories). However, they need nutrient-dense food to keep their immune systems strong. They may need more calcium and Vitamin D to protect thinning bones.

If we don't follow a balanced diet, it can lead to serious health problems. Here are the ones you need to know for your exam:

Obesity: Caused by eating more energy than we use. It increases the risk of heart disease and Type 2 diabetes.
Coronary Heart Disease (CHD): Often linked to eating too much saturated fat, which can clog the arteries.
High Blood Pressure: Often linked to eating too much salt (sodium).
Type 2 Diabetes: Where the body can't control blood sugar levels properly; often linked to obesity and high-sugar diets.
Bone Health: Rickets (in children) and Osteoporosis (in adults) are caused by a lack of Calcium or Vitamin D, making bones soft or brittle.
Dental Health: Tooth decay is caused by bacteria feeding on free sugars in the mouth.
Iron Deficiency Anaemia: Caused by a lack of Iron. It makes people feel tired, pale, and short of breath.

5. Planning Meals for Specific Groups

Sometimes, we have to adapt recipes for people with special dietary needs. Here is a quick guide:

Vegetarians and Vegans: They don't eat meat (or any animal products for vegans). They need to use protein complementation (eating two LBV proteins together, like beans on toast) to get all their essential amino acids.
Coeliacs: These people are intolerant to gluten (a protein found in wheat, barley, and rye). They must use gluten-free flours like coconut or rice flour.
Lactose Intolerant: These people cannot digest the sugar in milk (lactose). They should use alternatives like soya, almond, or oat milk.
High Fibre Diet: Needed to keep the digestive system healthy and prevent constipation. This involves eating plenty of whole grains, fruits, and vegetables.

6. Portion Size and Costing

When you are planning meals (like for your NEA 2 task!), you need to think about two practical things:

1. Portion Size: A portion for a toddler is much smaller than a portion for a hungry teenager. Using standardized "scoops" or weighing food helps keep portions consistent.
2. Costing: To calculate the cost of a recipe, you find the price of each ingredient based on the amount used. For example, if a \( 1kg \) bag of flour costs \( £1.00 \) and you use \( 500g \), that ingredient costs \( £0.50 \).
\( \text{Cost per portion} = \frac{\text{Total recipe cost}}{\text{Number of portions}} \)

Summary Checklist

- Can you name the sections of the Eatwell Guide?
- Do you know the energy percentages for protein (\( 15\% \)), fat (\( 35\% \)), and carbs (\( 50\% \))?
- Can you explain why a teenage girl needs more iron than a young child?
- Do you know which mineral is linked to high blood pressure? (It’s salt/sodium!)