3.1 Nutrients – Functions and sources

Nutrition for youth health

• One of the key behavioural determinants that affects the health and development of Australia’s youth is food intake

• Nutrition is the process of eating to nourish our bodies. It is also the scientific study of why we eat

Nutrients

• To understand how food affects health and development of youth, it is important to look at nutrients, how they work (function) and the foods they are found in (sources)

• Nutrients are the chemical components of food; they are required by living thing to maintain life

• There are many different types of nutrients

Types of nutrients

• The many different types of nutrients can be classified into two main forms:

• Macronutrients: Needed by the body in large quantities – proteins, carbohydrates, fats and water

• Micronutrients: Needed by the body in relatively small amounts – vitamins and minerals

Protein

• Main function: build, grow and repair cells• Made up of smaller units called amino acids• Classified as either complete or incomplete

depending on composition of amino acids• Food sources include: – Complete: meat, chicken, cheese, eggs, milk– Incomplete: rice, legumes, nuts, vegetables

Carbohydrate

• Main function: provide energy or fuel • Classified as monosaccharides, disaccharides or

polysaccharides • Food sources include: – Monosaccharides: glucose and fructose found in

honey and nuts– Disaccharides: sucrose and lactose found in sugar and

milk – Polysaccharides: Starch found in rice and pasta and

cellulose found in wholegrain breads and cereals

Fats

• Main function: Provide energy, provide insulation, supply fat-soluble vitamins and essential fatty acids

• Classified as: saturated, trans, monounsaturated and polyunsaturated

• Food sources include– Saturated: meat, butter, cream, coconut cream– Trans: hydrogenated vegetable fats, manufactured margarines,

cakes and biscuits (also found naturally in smaller quantities in meat and dairy)

– Monounsaturated: olives, olive oil, avocado, nuts– Polyunsaturated: some margarines, vegetable oils, oily fish such

as salmon, tuna and sardines

Water

• Most important nutrient of all• Essential for bodily functions, including:

digestion, absorption, circulation, regulation of temperature, lubrication, transportation of nutrients, oxygen and wastes

• Sources: fresh water, fruit and vegetables

Minerals

• Minerals are micronutrients, two important minerals are calcium and iron

Calcium

• Main functions: – forms hard structure of bones and teeth;

regulates contraction and relaxation of muscles; assists in blood clotting; transmits nerve impulses

• Main sources: – Milk and milk products, green leafy vegetables,

tofu and soy bean products, fish with edible bones such as tinned tuna, nuts and seeds

Iron

• Main functions: – Essential component of haemoglobin – the

pigment that gives blood its red colour– Formation of red blood cells

• Sources: – Red meat, chicken, seafood– Wholegrain breads and cereals, legumes, dark

green leafy vegetables

Vitamins

• Vitamins are also micronutrients, they include:– Vitamin A– Vitamin D– Vitamin C– B-group vitamins such as thiamin, riboflavin,

niacin and vitamin B12

Vitamin A

Functions Food sources

• Healthy vision• Healthy skin• Resistance to infection• Maintaining the mucous membranes that line the respiratory, gastrointestinal and urinary tracts as well as the mouth nose and ears• Normal growth of children, particularly teeth and bones

• Animal sources such as liver, oily fish, full-cream milk, egg yolk and cheese• orange and green fruit and vegetables such as carrots, spinach, broccoli, pumpkin, mango and apricots

Vitamin B

Functions Food sources

• absorption and metabolism of calcium and phosphorous to assist the formation of bones and teeth• cell growth and development• healthy functioning of the nervous system and the immune systems

• Fish, especially fish with a high fat content, such as sardines and salmon• meat, eggs and dairy products, including butter• fortified foods, such as margarine

Vitamin C

Functions Food sources

• formation of collagen, the connective tissue in skin, ligaments and bones• promoting the healing of wounds• absorption of iron / formation of red blood cells• preventing haemorrhaging and bleeding gums• fighting infection by maintaining white blood cells, which act as bacteria fighters • the production of thyroxin, a hormone involved in metabolism

• Fruit and vegetables such as: blackcurants, oranges, mangoes, pineapples, grapefruit, kiwi fruit, raspberries, capsicums, potatoes, broccoli and spinach

Thiamin (vitamin B1)

Functions Food sources

• Normal functioning of nerve cells • Muscle tone

• fortified breakfast cereals• yeast extracts (vegemite and marmite)• liver• kidney • lean pork• wholemeal bread• sesame seeds

Riboflavin (vitamin B2)

Functions Food sources

• Healthy skin and eyesight• Involved in the production of red blood cells

• yeast extracts (vegemite and marmite)• liver• lean red meat• chicken • fish• milk and milk products• eggs• wholegrain breads and cereals

Niacin (vitamin B3)

Functions Food sources

• blood circulation • reducing cholesterol levels in the blood• important for maintaining healthy digestive tract

• yeast extracts (vegemite and marmite)• wholegrain breads and cereals• fortified breakfast cereals • liver• fish • eggs

Pyridoxine (vitamin B6)

Functions Food sources

• metabolism of protein• production of red blood cells• development of the nervous system

• liver• lean red meat• fish • chicken• wholegrain breads and cereals

Cyano-cobalamin (vitamin B12)

Functions Food sources

• formation of red blood cells• formation of nerve cells and DNA genetic material• metabolism of carbohydrates and fats

• liver• kidney• meat • oysters • fish • seafood• eggs • milk