Food Composition

Food composition


Macro and micro nutrients


• Essential nutrients for life include: fats, proteins, carbohydrates, water, roughage (fibre), vitamins and minerals
• The macronutrients are required in large amounts and include: fats, proteins and carbohydrates
• The micronutrients are required in much smaller amounts



• Protein is required for growth and repair of tissue as well acting as: enzymes, carriers, hormones, immunity, buffering, etc…
• Proteins are made of chains of amino acids called polypeptides and amino acids can be classified as either essential, conditionally essential or non-essential. There are 21 in total.
• World Health Organisation recommends a daily intake of 0.75g of protein / kg body weight
• Protein can be found in animal derived sources (high biological value) and plant derived sources (low biological value)
• Protein sources include:




• The functions of fat include: an energy supply for cells 9Kcals/ g (38 KJ), to provide essential fatty acids, to act as a carrier for fat soluble vitamins (A,D,E,K) and antioxidants, to insulate the body and provide a reserve of energy, to protect the organs, to form brain tissues, nerves cell membranes,
required for making hormones and prostaglandins
• (WHO) recommend a daily fat intake of 20-35% dietary energy
• Sources of fat include: meat, fish, eggs, oils, nuts and seeds, some fruits and vegetables and many processed foods


• The functions of carbohydrate include:
• primary source of energy especially for the brain and nervous system, WHO RDA – 35 – 50% of dietary energy, protein sparing role, prevention of ketosis, maintenance of blood glucose levels
• Carbohydrates can be simple (sugars) or complex (starch and cellulose) in nature

• Insoluble fibre passes through the body undigested and prevents constipation
• Soluble fibre helps to lower bad cholesterol
                                                                                Grams of fibre in food



Micronutrients include both vitamins and minerals

• Vitamins can be either water soluble (B and C) or fat soluble (A, D, E and K)






                                                                    Water soluble vitamins are outlined below

• Deficiencies of water soluble vitamins include: Beri-Beri (B1 – Thiamine), Ariboflavinosis (B2 Riboflavin), Pellagra (Niacin), Spina Bifida / Megaloblastic anaemia (Folate) and Scurvy (Vitamin C)
• Minerals include: Calcium, phosphorous, magnesium, sodium, potassium, iron, zinc, copper, chromium, manganese, selenium, fluoride, Iodine

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