Micronutrients Vitamins

By the end of this topic… Developed a knowledge and understanding of Definition of vitamins Functions of vitamins Sources of vitamins Awareness of different types of vitamins Effects of excess & deficiency of vitamins in the diet Amounts needed for a healthy diet Sources AQA GCSE Food Preparation & Nutrition – Anita Tull Hammonds Cooking Explained – Jill Davies

What are vitamins? Complex chemical substances (carbon, hydrogen & oxygen) that are found naturally in unprocessed plant and animal foods They are micronutrients as the body only needs small amounts BUT needs a wide variety of different sources each day. The amount we need depends on our age and lifestyle Vitamins are divided into two categories Fat-Soluble – dissolves in fat & found in foods containing fat (Vitamins A, D, E & K) Water-Soluble – dissolves in water & found in foods that have a high water content (Vitamins B group & C) NB there are other vitamins – but these are the ones we need to learn for this GCSE

Fat Soluble Vitamins

Vitamin A Retinol Beta carotene Healthy skin, growth in children, Keeps eyes healthy (enable sight in dim light) Produces mucus to keep throat, digestive system, lungs etc moist, Antioxidant Too much (rare) toxic (poisonous) in pregnant women will damage foetus development Too little Can lead to total blindness, inability to see in dim light Vit A is stored in human liver & lack of it will take time for symptoms to appear Skin & mucus membranes become dry & infected Children fail to grow/develop normally Retinol found in oily fish, liver, eggs, milk, cheese, butter & margarine Beta carotene found in liver, green leafy vegetables, peas, orange (carrots) & red veg & fruit

Vitamin D Cholecalciferol Function in body Helps calcium be absorbed into digestion system Works with calcium to aid strong skeletal bones & teeth Too much (rare) Damage to kidneys & other vital organs Too little Bones will weaken (legs will bend under weight of body (rickets) or break easily (osteomalacia / osteoporosis) Teeth will be weak By law in the UK Vitamin D is added to vegetable spreads & breakfast cereals, Sources Sunshine Oily fish, meat, eggs, butter, vegetable fat, fortified breakfast cereals

Vitamin E Tocopherol Healthy blood & cell walls Antioxidant Function in body Healthy blood & cell walls Antioxidant Possibly reduces risk of developing some cancers & heart problems Too much (very rare) Too little (very rare) Sources Plant food – soya, corn oil, nuts, seeds, wheatgerm, vegetable fats, lettuce, egg yolk Soya beans

Vitamin K Phylloquinone Function in body Helps the blood to clot to prevent further blood loss Too much (rare) Too little Very rare in UK, but babies are given an injection of vitamin K within 24hours of being born Sources Cheese, liver, green leafy vegetables, cheese, green tea, asparagus, coffee

Water Soluble vitamins

B vitamins Sources Function Deficiency B1 B2 B3 (Niacin) B9 (Folate) (Thiamine) Meat, milk, cheese, eggs, added to breakfast cereals & flour, seeds, nuts Helps the release of energy from carbohydrates Can lead to beri-beri in which muscles & nerves affected, memory lost & lack of concentration B2 (Riboflavin) Eggs, milk & milk products, rice, mushrooms, Helps the release of energy from protein, carbohydrates & fat Swollen tongue, skin cracks around mouth, eye problems B3 (Niacin) Eggs, milk, meat, maize, wheat, yeast Enables energy to be released whilst breathing Diarrhoea, sore dry & cracked skin, memory loss, confusion B9 (Folate) Green leafy veg. peas, marmite, bananas Works with B12 to make healthy red blood cells. Anaemia, tiredness. Risk of spina bifida in unborn babies B12 (Cobalamin) Liver, meat, fish, cheese, yeast, fortified breakfast cereal Works with B9 to make healthy red blood cells. Keeps nerve cells healthy Anaemia, tiredness, shortness of breath. Loss of taste, smell.

Vitamin C Ascorbic Acid Function in body Needed to absorb iron from the intestine To maintain connective tissue which binds the body cells together (skin, blood, muscle etc) Helps wound healing Is an antioxidant Too little Iron deficiency (anaemia) Wounds take longer to heal / repair Bleeding from small blood vessels under skin which lead to red spots under skin & loose teeth Severe cases lead to scurvy Sources Citrus fruit & other vegetables, potatoes. Small amounts in milk & liver Too much Usually as a result of taking it in tablet form – diarrhoea, nausea & development of kidney stones

How much do we need to eat? Page 26 Only small amounts of vitamins are needed to maintain a healthy lifestyle BUT we need a wide variety of each. Vitamins are measured in Milligrams – mg (1mg = 1/1000 of a gram) Micrograms – mcg (1mcg = 1/1,000,000 of a gram) Complete the table Age/gender Vit A D E K B1 B2 B3 B9 B12 C 4 – 6 years Boy 15-18y Girl 15 – 18y Adult male Adult female Pregnant woman

Antioxidants By eating lots of different foods we have many chemicals going into our bodies. In the main they are not harmful, but when they combine with oxygen a reaction occurs. The chemicals become reactive “free radicals”. Free radicals can cause damage to cells which can lead to the body developing heart disease and some types of cancers Vitamins A, C & E are all antioxidants which help prevent people from developing health conditions

What happens during the preparation & cooking process? Vitamins B & C are water soluble and therefore loose or damage their nutritional content during cooking. B1, B2 & C can be further damaged by light & heat. In order to maximise their nutritional content following these simple rules Do not store foods for long periods & store in a cool, dark place. Prepare the fruit & vegetables close to the cooking time Avoid buying damaged / bruised goods Only cook in small amounts of water & use the water in stocks / sauces / gravies Serve the food immediately Steaming / stir fry vegetables reducing the loss of nutritents

Key Words & Practice Questions Ensure you have the correct definition of the following Fortified cereals Fat soluble Water soluble Antioxidant Deficiency Free radical Page 30 in text book – answer questions 1 & 2 in your books