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Core Topic 1: Fundamentals of Human Nutrition Macronutrients Protein What is Protein? Protein is a nutrient made up of carbon, hydrogen, oxygen and nitrogen. The only nutrient that supplies the body with nitrogen. Combine to create amino acids. 23 amino acids in total Classified as essential and non-essential amino acids. Provides 17kj/g of energy Located in animal and plant foods Why do we need Protein? Protein is required for: Growth, maintenance and repair of every cell in the body Production of enzymes, Haemoglobin, albumin & transferrin Production of antibodies enzymes enable chemical reactions (digestion) To activate the growth hormone as required Stabilising the structure of nucleic acids, DNA & RNA Create proteins in the blood Hair, finger nails, muscles to prevent diseases in the body As a secondary source of energy when carbohydrate and fat stores are depleted. Amino Acids Essential Amino Acids must be supplied in the diet given the body’s inability to make them. Non-Essential Amino Acids are synthesised by the body. Each Amino Acid is required to carry out the varied functions of protein Essential Amino Acids • Isoleucine • Leucine • Lysine • Methionine • Phenylalanine • Threonine • Tryptophan • Valine • Histidine (infancy only) Non-Essential Amino Acids • Alanine • Arginine • Asparagine • Aspartic Acid • Cysteine • Cystine • Glutamic Acid • Glutamine • Hydroxyproline • Proline • Serine • Tyrosine • Histidine (adulthood only) Biological Value, Complete & Incomplete Protein The biological value is a measure of the protein’s quality Biological value is measured by the number of essential amino acids it contains. Protein foods that contain all essential amino acids have a High Biological Value (HBV) and are known as: Complete Proteins: Protein foods that are deficient in one or more of the essential amino acids have a Low Biological Value (LBV) and are known as: Incomplete proteins. Complementary Proteins Two or more incomplete proteins can be combined to ensure each essential amino acid is consumed. Individually they have different limiting amino acids and are of LBV, but when combined they are considered of HBV. Nachos (corn & kidney beans) Minestrone Soup (legumes & vegetables) Combining two different sources of plant protein allows the amino acids to complement one another. Particularly important for vegetarians and vegans. Activity 1: Complete Protein Foods Meat Milk Cheese Eggs Fish Chicken Soy beans Incomplete Protein Foods Baked beans Pasta Potato Rice Peas Spaghetti Bread What foods can be combined to create complementary protein? Food Sources of Protein The proteins in animal food including meat, fish, eggs and milk are a rich source of protein. Plant foods including nuts, legumes, beans and grain contain some protein. How much protein? 17kj/g of energy 15-25% of the total daily energy intake should come from protein. The recommended intake of protein depends on a person’s weight and age. The RDI is expressed as grams per kilogram of bodyweight. Women require 0.75g of protein/kg of body weight Men require 0.84g/kg of protein/kg of body weight Pregnant women and men and women over 70 require 1g of protein/kg of body weight Q1. How many grams of protein will a 75kg adult male need? How much protein? NRVs for Protein – Infants There is no EAR or RDI for infants. The AI is 10g per day. NRVs for Protein – Children & Adolescence Age EAR g/per day RDI g/per day 1-3 yrs 4-8 yrs 12 16 14 20 Boys 9-13yrs 14-18yrs 31 49 40 65 Girls 9-13yrs 14-18yrs 24 35 35 45 NRVs retrieved from Nutrition: The Inside Story NRVs for Protein – Adults Age EAR g/per day RDI g/per day Men 19-70 yrs >70yrs 52 65 64 81 37 46 46 57 Women 19-70yrs >70yrs NRVs for Protein – Pregnancy & lactation Pregnancy 14-18yrs 47 19-50yrs 49 58 60 Lactation 14-18yrs 19-50yrs 63 67 51 54 How much protein? Group Protein intake (g/kg/day) Sedentary men and women 0.8-1.0 Elite male endurance athletes 1.6 Moderate-intensity endurance athletes (a) 1.2 Recreational endurance athletes (b) 0.8-1.0 Football, power sports 1.4-1.7 Resistance athletes (early training) 1.5-1.7 Resistance athletes (steady state) 1.0-1.2 Female athletes ~15% lower than male athletes Table 1: Estimated protein requirements for athletes Source: http://www.ausport.gov.au/ais/nutrition/factsheets/basics/protein_-_how_much Excess Protein Many Australians over-consume protein; thus, a deficiency is rare. Waste products from protein metabolism are processed and removed by the liver and kidneys. If protein consumption is excessive these organs are placed under additional strain. Increased protein consumption increases the risk of dietary related disorders including obesity, heart disease and increased blood cholesterol levels. Due to increased levels of saturated fats, which increases blood cholesterol levels, and provides many kj/g. Q. In pairs suggest 3 reasons why many Australians over consume protein. Deficiency of Protein Insufficient protein intake can lead to: Retarded growth in children Slow healing of wounds Decreased levels of immunity due to insufficient antibodies. Anaemia due to insufficient haemoglobin. Kwashiorkor is a condition found in developing countries where there is a deficiency in the quality and quantity of dietary protein. Symptoms include wasted muscles, protuberant belly, brittle hair and failure to grow, peeling skin and apathy. Deficiency of Protein When both protein and energy (kj) are in short supply , marasmus can occur. Symptoms of Marasmus include: Retarded growth Extreme muscle wastage Sunken eyes General debility Vegetarian Diets and Protein Vegetarian diets are classified into four main types: Vegan Lacto-Vegetarian Avoid meat and eggs, but include dairy products Lacto-Ovo Vegetarian Avoid eating all animal products and foods. Avoid eating all animal products, but will consume milk, milk products and eggs Vegetarian ‘loose’ term to describe people who do not eat animal foods Concerns with Vegetarianism Vitamin B12 and iron are concerns for a poorly balanced vegetarian diet. To ensure essential amino acids are consumed , people need to consume complementary proteins. Eat foods from two different food sources within the same meal. E.g. cereals with legumes or vegetables and legumes. A food model for a lacto-Ovo vegetarian (Nutrition Australia 2013) Extended Response ‘Provided you get the correct amount of protein on a regular basis in your diet, it is of little consequence what food sources it is derived from.’ Outline four main functions of protein in the diet. Discuss the importance of careful protein selection for vegetarians and their young children. Discuss the positive and negative aspects of being an adolescent female lacto-vegetarian . Discuss whether animal proteins are better for us than proteins from plant products.
