Macronutrients Carbohydrates Carbohydrates are an energy source made by plants during photosynthesis. This plant energy provides human energy when eaten.

The functions of carbohydrates Carbohydrates are needed for: Providing energy Acting as a ‘protein sparer’ Dietary fibre (a carbohydrate) produce soft, bulky faeces that help the body to get rid of waste products when going to the toilet If the diet is low in carbohydrate, then protein is used as an energy source. Carbohydrate should stop the use of protein as an energy source so that the protein can continue its primary function for growth and repair. Carbohydrates exist in many forms. They can be divided into three groups: Sugars Starches Dietary Fibre Sugars are the simplest form of carbohydrates Complex carbohydrates are starches and fibre

Sources of carbohydrate 1.Sugars Monosaccharides (single/simple sugars) Glucose (fruit, onions, potatoes) Fructose (fruit, honey) Galactose (milk) Disaccharides (double sugars) Lactose = glucose + galactose (milk, yoghurt, cream, cheese) Maltose = glucose + glucose (cereals like barley, used to make breakfast cereals, biscuits, beer, malty hot drinks) Sucrose = glucose + fructose (sugar beet or sugar cane – granulated, caster, demerara, treacle, icing, golden syrup)

Free sugars and fruit sugars Another way to classify sugars is according to where it is found in food Free sugars: Sugars that are added to food or found outside the cell structure. Free sugars are processed sugars, such as: Granulated, Caster, Demerara, Icing sugar, Treacle, Golden syrup They include the sugar found in honey and unsweetened fruit juices. Fruit sugars: naturally found inside fruit and vegetable cells. Sometimes called natural sugars Hidden sugars are found in foods you would not expect to contain sugar i.e. salad dressings, sauces, soups, bread. Normally highly processed foods – look carefully at food labels to identify hidden sugars A diet high in free sugars can lead to tooth decay and obesity. Sugar provides energy but contains no other nutrients.

2. Starches Starches are complex carbohydrates also known as POLYSACCHARIDES. Polysaccharides are long chains of one type of monosaccharide joined together. They are thus big molecules and most are insoluble in water. The most important starches are: a. Starch Starch is the energy reserve of plants. It can be recognised under microscope by its shape that is granular with a size and shape distinctive to each plant. Nutritionally starch is important because it provides the body with a slow release form of energy from the carbohydrate which the starch provides. Unlike the monosaccharides however, starchy foods can provide other essential nutrients to the diet, including protein, fat, the B-group of vitamins, vitamin C in the case of potatoes, potassium, copper, calcium, selenium, magnesium, manganese, iron and non-starch polysaccharide. Sources: cereals (wheat, rice, oats, barley, maize/corn, biscuits, pastries, cake, bread, breakfast cereal), starchy vegetables (potato, yam, sweet potato, parsnip, pumpkin, butternut squash, peas, beans, lentils), seeds, quinoa

Main importance: Gelling agent for jam making b. Pectin Complex mixture of polysaccharides found in many fruits and some root vegetables i.e. apples, the peel of citrus fruits, apricots, plums and some root vegetables i.e. Main importance: Gelling agent for jam making Pectin is broken down in fruit as fruit ripens – jam will not gel well if made from over ripe fruit. pH affects gel strengths i.e. lemon juice lowers this setting. (It is actually classified as a soluble NSP (Non-Starch Polysaccharide) as it forms a gel in water) c. Glycogen Small amount are stored in the muscles and liver and when required, the human body (and other animals) converts it to glucose which provide energy.

3. Dietary Fibre (NSP – Non-Starch Polysaccharides) A non-starch polysaccharide found in the cell walls of vegetables, fruits, pulses and cereal grains. It acts as a bulking agent absorbing the end-products of digestion to allow waste products to be removed from the body They have the ability to hold water and thus aid peristalsis. Heating may soften the cellulose, but it does not gelatinise as starch does, thus remaining undigested in the digestive system, aiding peristalsis. Function: Allowing the digestive system to remain healthy and function properly Leaving us feeling fuller for longer and thus therefore help with weight control Prevent some bowel diseases i.e. constipation, diverticulitis, bowel cancer Providing soluble fibre (pectin) which can help to reduce cholesterol levels

Sources of dietary fibre (NSP) Two types of dietary fibre: soluble and insoluble Soluble Insoluble Oats Wholegrain foods (wholegrain bread, Nuts breakfast cereal, pasta) Legumes (peas, beans, lentils) Brown rice Fruit (prunes, apples, pears, plums, Wheat bran part of citrus peel) Fruit and vegetable peel and skins Vegetables (flesh of potato, sweet Nuts and seeds potato, carrot)

Excess and Deficiency Sugars and Starches Excess: Convert into fat and stored in the body if not used for energy and lead to weight gain (obesity) Tooth decay Deficiency: Lack of energy Tiredness/fatigue Weight loss 2. Dietary fibre Excess: A diet rich in in cereals can reduce the body’s ability to absorb iron and calcium . The cereal can bind with the minerals making them less likely to be absorbed in the intestines. Deficiency: Can contribute towards constipation which could lead to an increase in bowel cancer

DRVs for sugars and starches High intakes of free sugars have been linked to tooth decay and obesity. Free sugars need to be reduced in the diet and should be restricted to providing 5% of daily energy (calorie) requirements. This is about 30g of sugar a day for those aged 11 and over. All population groups exceed this recommendation. Teenagers’ intakes are the highest of all groups – they consume 50% more sugar on average than is currently recommended.

DRVs for fibre SACN (Scientific Advisory Committee on Nutrition) recommends a Dietary Reference Value (DRV) for dietary fibre of 30g for adults. Children should eat less because of their small body size. Very young children should avoid too many fibre rich foods as being full up with fibre can make it difficult for them to meet their other nutritional needs.