Protein Complementation and Recommendations

Protein complementation is a strategy to create a complete protein profile by combining different LBV protein sources. This is particularly important for vegetarians and vegans to ensure they receive all essential amino acids.

Examples of protein complementation:

• Rice and beans
• Beans on toast
• Hummus and pitta bread

Example: A protein complementation meal might consist of rice and lentils, which together provide all essential amino acids.

Key terms:

• Amino acids: Building blocks of protein
• Essential amino acids: Amino acids the body cannot produce

Protein recommendations:

• Men: 56g per day
• Women: 45g per day
• 12% of dietary energy
• 0.75g of protein per kg of body weight

Highlight: High biological value protein function is crucial for growth, repair, and maintenance of body tissues.

Exam Question and Protein Alternatives

Exam question: Explain the differences between high and low biological value proteins (6 marks)

Answer: HBV proteins contain all essential amino acids that the body can't produce. Examples include meats, tofu, and fish. Without these, the chain of amino acids would be incomplete, and proteins couldn't be formed properly.

LBV proteins lack one or more essential amino acids. Examples include nuts, seeds, and cereals. To address this issue, protein complementation can be used by mixing LBV proteins (e.g., rice and peas) to obtain all essential amino acids.

Protein alternatives:

• Soya bean products (tofu, miso, soya milk)
• Mycoprotein (Quorn)

Advantages of these alternatives:

• High HBV protein content
• High in fiber
• Low in fat

Disadvantages:

• Low in minerals
• Low in vitamins (often fortified with B12)

Highlight: Understanding protein complementation is essential for those following vegetarian or vegan diets to ensure adequate intake of all essential amino acids.

Carbohydrates: Structure and Function

Carbohydrates play a crucial role in providing energy and acting as a "protein sparer." This means that when carbohydrates are present in sufficient amounts, protein can be used for its primary functions of growth and repair rather than being broken down for energy.

Structure of carbohydrates:

1. Simple sugars
   • Monosaccharides: Single unit (e.g., glucose)
   • Disaccharides: Two units (e.g., sucrose - glucose + fructose)
2. Complex carbohydrates (polysaccharides): Many units (e.g., starch, fiber)

Definition: Complex carbohydrates are long chains of sugar molecules that take longer to digest, providing sustained energy.

Functions of carbohydrates:

• Primary energy source (50% of our energy should come from carbohydrates)
• Slow release of energy
• Good source of fiber

Highlight: Choosing complex carbs for weight loss can be beneficial due to their slower digestion and ability to promote feelings of fullness.

Types of Carbohydrates and Their Effects

Simple sugars:

• Quick release of energy
• Can affect mood
• May contribute to tooth decay
• Linked to diabetes and acne

Types of carbohydrates:

1. Simple sugars
2. Starch
3. Fiber

Free sugars and fruit sugars:

• Free sugars: Added to food or found outside the cell structure
• Fruit sugars: Naturally occurring in fruits and vegetables

Vocabulary: Free sugars include processed sugars like granulated, caster, demerara, and icing sugar, as well as those found in honey and unsweetened fruit juices.

Hidden sugars:

• Found in unexpected foods like bread, salad dressing, and ketchup
• Can lead to tooth decay and obesity

Highlight: Being aware of hidden sugars in processed foods is crucial for maintaining a healthy diet and preventing excessive sugar intake.

Polysaccharides and Starch

Polysaccharides are complex carbohydrates composed of many monosaccharide molecules (glucose) joined together. Examples include starch and fiber.

Starch:

• Should provide 50% of food energy from carbohydrates (current average diet is 38%)
• Offers slow release of energy
• Adds bulk to the diet, making you feel fuller
• Excess is converted to fat

Tips for increasing starch intake:

• Choose whole grains
• Opt for whole oats and porridge
• Base meals on starchy foods
• Switch from white to brown varieties (e.g., rice, pasta)
• Change to starchier vegetables

Example: Complex carbs list includes foods like whole grain bread, brown rice, quinoa, and sweet potatoes.

Highlight: Incorporating more complex carbohydrates into your diet can help stabilize blood sugar levels and provide sustained energy throughout the day.

Carbohydrate Recommendations and Sugar Effects

Dietary Reference Values (DRV) for carbohydrates:

• 45% of energy from starchy carbohydrates, milk sugar, and fruit sugar
• 50% of total food energy from carbohydrates
• No more than 5% from free sugars

Effects of sugar on the body:

1. Tooth decay
2. Type 2 diabetes: Excessive sugar intake can lead to insulin resistance
3. Mood swings
4. Hyperactivity

Highlight: Limiting free sugar intake is crucial for maintaining overall health and preventing chronic diseases.

Example: Choosing healthy simple carbs like fruits can provide necessary sugars along with beneficial vitamins and fiber.

Fiber and Water

Foods high in fiber:

• Fruits (with skin)
• Whole grains
• Beans and lentils (pulses)
• Nuts and seeds

Daily fiber intake recommendation: 30g/day (for adults)

Fiber functions:

• Prevents bowel disorders
• Aids in weight control
• Lowers blood cholesterol
• Promotes feeling fuller for longer
• Prevents constipation

Definition: Fiber is non-digestible cellulose found in plant foods that absorbs water, increases bulk in feces, and aids digestion.

Importance of fiber in a teenager's diet (6 marks):

1. Weight control: Fiber promotes fullness, reducing snacking and calorie intake
2. Heart health: Fiber helps lower blood cholesterol, reducing the risk of heart problems
3. Digestive health: Fiber prevents bowel disorders and softens feces, making elimination easier

Highlight: Adequate fiber intake is crucial for maintaining digestive health and preventing various chronic diseases.

Protein Structure and Sources

Proteins are composed of amino acids, with 20 different types existing. The human body can produce 12 non-essential amino acids, while the remaining 8 (10 for children) are essential and must be obtained through diet.

Protein sources are categorized based on their amino acid profiles:

1. High biological value (HBV) proteins: Contain all essential amino acids

   • Animal sources: meat, fish, poultry, and dairy
   • Vegetarian sources: soya, tofu, and quorn

2. Low biological value (LBV) proteins: Lack one or more essential amino acids

   • Vegetarian sources: cereals, pulses, beans, nuts, and seeds

Vocabulary: Biological value of protein refers to the proportion of absorbed protein that can be used by the body.

Highlight: Understanding the difference between HBV and LBV proteins is crucial for maintaining a balanced diet, especially for vegetarians and vegans.