Functions of proteins • Growth of body cells (skin, blood, tissues and bone)
• Repair of damaged cells (cuts) • Produce heat (temperature control) • Provide energy (ability to work) • Produce important body chemicals such as enzymes, hormones and antibodies
Reference Intake (RI) of proteins
Adults need approximately 1 g of protein per 1 kg of body weight daily. Children and teenagers need more because they are growing.
Further Investigation Find out more about plant foods as a source of protein by going to www.care2.com and searching for ‘Best Protein Alternatives to Meat Besides Tofu’ ( see vegetarian diets, p. 68).
Revision Questions
1. Explain the following terms: (a) amino acid, (b) essential amino acids and (c) high biological value.
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2. Classify protein and give four sources in each class. 3. Explain the importance of protein in the diet of (a) a pregnant woman, (b) children and (c) an older person.
Carbohydrates Light energy Oxygen Carbon dioxide
Key Words 3Photosynthesis 3Source 3Glucose 3Sugar
3Fibre 3Starch 3Vegetable 3Constipation
Water Photosynthesis 24
Carbohydrates are found in plant foods only and are the most plentiful nutrient. Plants can manufacture their own food by a process called photosynthesis.
Protein deficiency symptoms • Poor or stunted growth • Slow healing • Poor general health • Imbalance of hormones and enzymes • The body is open to infection and disease as fewer antibodies are produced
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Strand 1: Food, Health and Culinary Skills Section 2: Nutrition Know-How
