Function and food sources of major nutrients as

Function and food sources of major nutrients as a determinant of health and the Glycaemic Index

Nutrition • Process of eating to nourish the body • Describes the scientific study of why we eat

Nutrients • Classified into two main forms • Macronutrients: required by the body in large amounts – proteins, carbohydrates, fats and water • Micronutrients: required by the body in relatively small amounts – mainly vitamins and minerals

Protein Macronutrient 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 • Macronutrient • 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

Carbohydrates: Dietary fibre • Made up of a number of carbohydrates • Passes relatively undigested through body • Main function is to provide bulk and assist with waste removal • Food sources: wholegrain breads and cereals, bran, wholemeal pasta, brown rice, dried fruits and nuts, fresh fruits and vegetables especially with skin on

Carbohydrates: Glycaemic Index • GI relates to the ranking of carbohydrate foods according to the effect on blood glucose levels • Low GI foods are broken down more slowly, resulting in a gradual increase in blood sugar levels providing sustained energy • High GI foods are broken down more quickly resulting in an rapid increase in blood sugar levels

Fats (lipids) • Macronutrient • 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 • Macronutrient • Most important nutrient of all • Essential for bodily functions, including: digestion, absorption, circulation, regulation of temperature, lubrication, transporation of nutrients, oxygen and wastes • Sources: fresh water, fruit and vegetables

Minerals • Minerals are micronutrients, they include: – Calcium – Phosphorus – Iron – Iodine – Fluoride – Sodium

Vitamins • Vitamins are also micronutrients, they include: – Vitamin A – Vitamin D – Vitamin C – Folate – Vitamin B 12 – Other B-group vitamins such as thiamin, riboflavin and niacin