Welcome to the World of Micronutrients!
In this chapter, we are exploring the "little heroes" of our diet: Micronutrients. While macronutrients (protein, fats, and carbohydrates) provide the bulk of our food, micronutrients are needed in much smaller amounts. However, don't let their size fool you! Without them, our bodies wouldn't be able to grow, repair themselves, or function properly. Think of them like the "spark plugs" in a car engine—they don't provide the fuel, but the car won't start or run without them!
1. Vitamins
Vitamins are organic compounds that help our bodies perform hundreds of different roles. They are divided into two main groups based on how our bodies absorb and store them.
A. Fat-Soluble Vitamins
These vitamins are found in foods containing fat. They are absorbed with the help of fat and stored in the body’s liver and fatty tissues for later use. This means we don't necessarily need to eat them every single day.
Memory Aid: Just remember ADEK ("All Dogs Eat Kibble") to remember the four fat-soluble vitamins: A, D, E, and K.
1. Vitamin A (Retinol/Beta-carotene)
Functions: Keeps the immune system working, helps us see in dim light, and keeps skin healthy.
Sources: Liver, oily fish, eggs (Retinol); carrots, spinach, and orange-coloured fruits (Beta-carotene).
Deficiency: Can lead to night blindness (difficulty seeing in the dark).
Excess: Too much can be toxic, especially during pregnancy.
2. Vitamin D (The "Sunshine Vitamin")
Functions: Helps the body absorb calcium to keep bones and teeth strong.
Sources: Sunlight on the skin, oily fish, egg yolks, and fortified spreads.
Deficiency: Can lead to Rickets in children (soft, weak bones) or Osteomalacia in adults.
Quick Review: Our bodies make Vitamin D from sunlight, but in the UK winter, we often need to get it from food or supplements.
3. Vitamin E
Functions: Acts as an antioxidant to protect cells from damage and keeps skin and eyes healthy.
Sources: Vegetable oils, nuts, seeds, and leafy greens.
4. Vitamin K
Functions: Crucial for blood clotting (helping wounds heal so we don't keep bleeding).
Sources: Leafy green vegetables (broccoli, spinach) and some cereals.
B. Water-Soluble Vitamins
These vitamins (The B group and Vitamin C) dissolve in water. Our bodies cannot store them easily, and we pee out any extra. This means we need to eat them almost every day!
1. The B Group Vitamins
Most B vitamins are involved in releasing energy from food.
- B1 (Thiamin): Helps energy release and keeps the nervous system healthy. Found in whole grains and pork.
- B2 (Riboflavin): Helps energy release and skin health. Found in milk, eggs, and leafy greens.
- B3 (Niacin): Helps energy release and nervous system health. Found in meat, flour, and eggs.
- Folic Acid (Folate): Essential for pregnant women to prevent neural tube defects (like Spina Bifida) in babies. Found in green leafy veg.
- B12: Helps make red blood cells. Found in meat, fish, and dairy (vegans may need a supplement).
2. Vitamin C (Ascorbic Acid)
Functions: Helps heal wounds, supports the immune system, and helps the body absorb iron.
Sources: Citrus fruits (oranges, lemons), strawberries, peppers, and broccoli.
Deficiency: Can cause Scurvy (bleeding gums and tiredness).
How Cooking Affects Water-Soluble Vitamins
Don't worry if this seems tricky at first, just remember that water-soluble vitamins are fragile!
1. Heat: High temperatures can destroy Vitamin C and B group vitamins.
2. Water: Boiling vegetables in water causes these vitamins to dissolve into the water. If you pour the water down the sink, the vitamins go with it!
Pro-tip: Use steaming or microwaving to keep more vitamins in your food.
Key Takeaway: Fat-soluble vitamins (ADEK) are stored in the body; water-soluble vitamins (B and C) need to be replaced daily and can be lost during cooking.
2. Antioxidant Functions of Vitamins
Some vitamins act as Antioxidants. Think of these as "bodyguards" that protect our cells from Free Radicals (harmful molecules that can cause heart disease and cancer).
The main antioxidant vitamins are A, C, and E.
Did you know? You can remember the antioxidants by the word ACE!
3. Minerals
Minerals are inorganic substances. We only need small amounts, but they are vital for structural parts of the body (like bones) and chemical reactions.
1. Calcium
Functions: Building strong bones and teeth; helps blood clot.
Sources: Milk, cheese, yoghurt, sardines, and fortified white flour.
Deficiency: Can lead to Osteoporosis (brittle bones) later in life.
2. Iron
Functions: Needed to make Haemoglobin in red blood cells, which carries oxygen around the body.
Sources: Red meat, kidney, spinach, and fortified breakfast cereals.
Deficiency: Leads to Anaemia (feeling very tired, pale, and weak).
Quick Review: Eating Vitamin C with Iron-rich foods helps your body absorb the iron better!
3. Sodium (Salt)
Functions: Maintains fluid balance in the body.
Sources: Salt, processed foods, and snacks.
Excess: Too much sodium is linked to High Blood Pressure, which can lead to heart disease.
4. Fluoride
Functions: Strengthens tooth enamel and prevents tooth decay.
Sources: Drinking water (in some areas) and toothpaste.
5. Iodine
Functions: Helps the thyroid gland produce hormones that control the body's metabolism and growth.
Sources: Seafood, seaweed, and milk.
6. Phosphorus
Functions: Works with calcium to build strong bones and teeth.
Sources: Red meat, dairy, and fish.
Key Takeaway: Calcium is for bones, Iron is for blood, and Sodium is for fluid balance. Balance is key—too much or too little can cause health problems.
4. Water and Hydration
Water isn't a vitamin or mineral, but it is the most important nutrient for survival! About \(60\%\) of our body is made of water.
Functions of Water:
- Eliminate waste: Helps the kidneys flush out toxins.
- Cooling: We sweat to lower our body temperature.
- Digestion: Helps move food through the digestive system.
- Lubrication: Keeps joints and eyes moist.
How we lose water: Through breath, sweat, and urine.
How much do we need? The general guideline is about 2 litres (6-8 glasses) a day.
When do we need EXTRA fluids?
- During hot weather (to replace sweat).
- When exercising.
- When we are ill (especially with fever or vomiting).
- Pregnant or breastfeeding women need more fluid.
Common Mistake to Avoid: Don't wait until you feel "thirsty" to drink. Thirst is often a sign that you are already slightly dehydrated!
Key Takeaway: Hydration is vital for every body process. Drink 6-8 glasses a day, and more if you're active or it's hot!
Quick Summary Checklist
- Can you name the ADEK fat-soluble vitamins?
- Do you know which mineral prevents Anaemia?
- Why should we steam vegetables instead of boiling them?
- Who needs Folic Acid the most?
- What are the three ACE antioxidant vitamins?