Diet and Nutrition Basics

Think of food as your body's petrol - without it, you can't grow, move, stay warm, or even repair a cut on your finger. Your diet (everything you eat) needs to provide energy measured in Joules, plus all the building blocks your body craves.

There are six main nutrient groups your body depends on. Carbohydrates like bread and pasta are your main energy source, whilst proteins from meat and beans help you grow and repair damage. Fats might sound scary, but they actually insulate your organs and form part of every cell membrane.

Don't forget the unsung heroes either. Fibre keeps your digestive system running smoothly (even though you can't actually digest it), whilst water is essential for virtually every chemical reaction happening inside you right now.

Quick Tip: Remember that vitamins and minerals each have their own special jobs - there's no single "superfood" that does everything!

Testing for Nutrients in Food

Ever wondered how scientists figure out what's actually in your food? These simple food tests are surprisingly straightforward and might just pop up in your next practical exam.

For starch, you'll use iodine solution - it changes from boring brown to dramatic blue-black when starch is present. Testing for glucose requires Benedict's solution and a hot water bath, creating a colourful rainbow from blue through green and orange to brick red. The redder it gets, the more sugar is lurking in your sample.

Protein testing uses Biuret solution, which shifts from blue to lilac purple. For lipids (fats), you'll mix your sample with ethanol then add water - if fats are present, you'll see a cloudy white layer appear.

Want to measure how much energy is stored in food? Calorimetry involves burning food samples and measuring how much the surrounding water heats up. The formula is: Energy = mass of water × temperature change × 4.2.

Exam Alert: Learn the colour changes for each test - they're guaranteed to show up in multiple choice questions!

Vitamins, Minerals and Individual Dietary Needs

Your body is constantly changing, which means your nutritional needs change too. Vitamin D helps you absorb calcium from oily fish and egg yolks, keeping your bones strong. Meanwhile, Vitamin C from citrus fruits repairs tissues and maintains your immune system.

Iron from red meat creates haemoglobin (the stuff that makes blood red), whilst calcium from dairy products builds bones and teeth. Missing any of these leads to deficiency diseases - think scurvy from lack of Vitamin C or anaemia from insufficient iron.

Your personal needs depend on loads of factors. Active teenagers need more calories and protein than elderly people because you're growing and burning energy faster. Men generally need more daily calories, whilst women need extra iron during menstruation and more of everything during pregnancy.

Malnutrition isn't just about not eating enough - it's about poor nutrition in general, which can happen from eating too much of the wrong things or not enough of the right ones.

Real Life: Understanding your changing nutritional needs helps explain why your appetite might vary during growth spurts or busy periods!