Introduction
Welcome to this chapter on Water, Dietary Fibre (NSP), and Food Energy! While vitamins and minerals often get all the attention, these three components are the "behind-the-scenes" heroes of your body. Without them, your body wouldn't have the fuel to move, the tools to clean itself, or the ability to keep its systems running smoothly. Let's dive in and see why they are so vital for a healthy life!
1. Water: The Body's Life Support
You might have heard that the human body is made up of about \(60\%\) to \(70\%\) water. Because we lose water constantly through breathing, sweating, and going to the bathroom, we must replace it every single day.
Functions of Water
Why do we need it? Water does much more than just quench your thirst:
- Transport: Water is the main part of blood. It carries nutrients to your cells and carries waste products away.
- Temperature Control: When you get too hot, you sweat. As the water evaporates from your skin, it cools you down.
- Waste Removal: It helps the kidneys flush out toxins from the body in the form of urine.
- Digestion: It helps soften food and allows nutrients to be absorbed in the digestive tract.
- Lubrication: It keeps your joints (like knees and elbows) moving smoothly and protects sensitive tissues like your eyes.
- Chemical Reactions: Many of the body's internal processes, like metabolism, require water to happen.
Sources of Water
We don't just get water from a glass! We get it from:
- Drinks: Plain water, milk, fruit juices, and tea.
- Foods: Many fruits and vegetables have a very high water content. For example, cucumber, watermelon, and lettuce are mostly water.
- Metabolic Water: Small amounts of water are actually produced inside your body when it breaks down food for energy.
Quick Tip: If you feel thirsty, you are already slightly dehydrated! It is better to sip water regularly throughout the day.
2. Dietary Fibre (NSP)
In your exam, you will see this called Non-Starch Polysaccharide (NSP). Don't let the long name scare you! It simply refers to the parts of plant foods that your body cannot digest. Even though we can't absorb it, it is essential for keeping our digestive system healthy.
Functions of NSP / Dietary Fibre
- Prevents Constipation: Fibre acts like a "broom" for your intestines. It adds bulk to faeces and holds onto water, making waste soft and easy to pass.
- Feeling of Fullness (Satiety): High-fibre foods take longer to chew and stay in the stomach longer, helping you feel full and preventing overeating.
- Disease Prevention: A diet high in fibre is linked to a lower risk of bowel cancer and heart disease.
- Stimulates Peristalsis: The bulk of the fibre stretches the walls of the intestine, which triggers the muscles to push food through the system (a process called peristalsis).
Sources of NSP / Dietary Fibre
Fibre is only found in plant foods. You won't find it in meat, fish, or dairy. Good sources include:
- Cereals: Wholemeal bread, brown rice, whole-wheat pasta, and oats (porridge).
- Pulses: Lentils, chickpeas, and beans (like kidney beans or baked beans).
- Vegetables: Especially those with skins or stalks, like broccoli, carrots, and peas.
- Fruits: Especially those where you eat the skin, like apples and pears, or fruits with seeds like raspberries.
Common Mistake to Avoid: Many students think white bread is a good source of fibre. It isn't! During processing, the outer "bran" layer of the grain (which contains the fibre) is removed. Always choose whole-grain or wholemeal versions for maximum fibre.
3. Food Energy
Just like a car needs petrol or electricity to move, your body needs energy to function. Even when you are sleeping, your heart is beating and your lungs are breathing—this all requires energy!
Sources of Food Energy
The body gets its energy from three main nutrients (which you will study in more detail in other chapters):
- Carbohydrates: The body’s preferred and quickest source of energy.
- Fats: A concentrated source of energy, providing more than twice as much energy as carbohydrates.
- Proteins: Usually used for growth and repair, but can be used for energy if the body doesn't have enough carbohydrates or fats.
Uses of Food Energy
Our body uses energy in two main ways:
- Basal Metabolism: This is the minimum energy needed just to keep you alive (keeping your heart beating, lungs working, and body temperature stable) while you are at rest.
- Physical Activity: Any movement you do, from walking to the kitchen to running a marathon, uses extra energy.
Did you know? Different people need different amounts of energy. For example, a professional athlete or a construction worker will need much more food energy than someone who sits at a desk all day!
Quick Review: Key Takeaways
Water: Essential for transport, cooling (sweat), and cleaning the body. Found in drinks and "juicy" foods.
NSP (Fibre): Found in plant skins and whole grains. It prevents constipation by keeping the digestive system moving.
Energy: Comes mainly from carbohydrates and fats. We need it for basic life functions (metabolism) and physical movement.
Key Terms to Remember:
NSP: Non-Starch Polysaccharide (the scientific name for dietary fibre).
Peristalsis: The wave-like muscle contractions that move food through the gut.
Metabolism: The chemical processes in the body that keep us alive.