State the principal dietary sources and describe the importance of: (a) carbohydrates (b) fats and oils (c) proteins (d) vitamins, limited to C and D (e) mineral ions, limited to calcium and iron (f) fibre (roughage) (g) water

A balanced diet is essential for maintaining overall health, and it includes various nutrients that play crucial roles in bodily functions. Here’s a detailed overview of the principal dietary sources and importance of carbohydrates, fats and oils, proteins, vitamins (C and D), mineral ions (calcium and iron), fiber, and water.

(a) Carbohydrates

• Dietary Sources: Whole grains (brown rice, oats, whole wheat bread), fruits (bananas, apples), vegetables (potatoes, corn), legumes (beans, lentils).
• Importance: Carbohydrates are the body’s primary source of energy. They are broken down into glucose, which fuels brain function and physical activity. Complex carbohydrates also provide dietary fiber, which aids digestion and helps regulate blood sugar levels. A diet rich in carbohydrates can reduce the risk of chronic diseases such as heart disease and diabetes.

(b) Fats and Oils

• Dietary Sources: Healthy fats are found in avocados, nuts (almonds, walnuts), seeds (chia, flaxseeds), olive oil, and fatty fish (salmon, mackerel). Unhealthy fats include saturated fats from processed foods.
• Importance: Fats are vital for absorbing fat-soluble vitamins (A, D, E, K) and providing essential fatty acids that the body cannot synthesize. They also contribute to hormone production and help maintain cell membranes. Healthy fats can improve heart health by reducing bad cholesterol levels.

(c) Proteins

• Dietary Sources: Animal sources include meat, fish, eggs, and dairy products. Plant sources include legumes (lentils, chickpeas), nuts, seeds, and whole grains.
• Importance: Proteins are essential for building and repairing tissues, producing enzymes and hormones, and supporting immune function. They are made up of amino acids; some of these are essential and must be obtained through diet. Adequate protein intake is crucial for growth, especially in children and during recovery from illness or injury.

(d) Vitamins

• Vitamin C Sources: Citrus fruits (oranges, lemons), strawberries, bell peppers, broccoli.
• Importance: Vitamin C is an antioxidant that supports immune function, promotes wound healing, and aids in iron absorption.
• Vitamin D Sources: Fatty fish (salmon, mackerel), fortified dairy products, egg yolks, sunlight exposure.
• Importance: Vitamin D is crucial for calcium absorption and bone health. It also plays a role in immune system regulation.

(e) Mineral Ions

• Calcium Sources: Dairy products (milk, cheese), leafy green vegetables (kale, broccoli), fortified plant milks.
• Importance: Calcium is essential for building strong bones and teeth. It also plays a role in muscle function and nerve transmission.
• Iron Sources: Red meat, poultry, fish, lentils, beans, spinach.
• Importance: Iron is vital for the production of hemoglobin in red blood cells, which transports oxygen throughout the body. Adequate iron intake helps prevent anemia.

(f) Fiber (Roughage)

• Dietary Sources: Whole grains (oats, brown rice), fruits (apples with skin), vegetables (carrots), legumes (beans).
• Importance: Dietary fiber aids in digestion by promoting regular bowel movements and preventing constipation. It also helps control blood sugar levels and lowers cholesterol levels, reducing the risk of heart disease.

(g) Water

• Sources: Drinking water, fruits (watermelon), vegetables (cucumbers), soups.
• Importance: Water is essential for maintaining hydration, regulating body temperature, transporting nutrients and waste products in the body. It plays a critical role in metabolic processes and helps maintain cellular functions.