core topic 1: fundamentals of human nutrition macronutrients protein
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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 energyLocated in animal and plant foods
Why do we need Protein?
Protein is required for: Growth, maintenance and repair of every cell in the
body Hair, finger nails, muscles
Production of enzymes, 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
Haemoglobin, albumin & transferrin Production of antibodies
to prevent diseases in the body As a secondary source of energy when
carbohydrate and fat stores are depleted.
Amino Acids
Essential AminoAcids must be supplied in the dietgiven the body’s inability to make them.
Non-Essential Amino Acids are synthesised by thebody.
Each Amino Acidis required to carryout the varied func-tions of protein
Essential Amino Acids
Non-Essential Amino Acids
• Isoleucine • Leucine• Lysine • Methionine• Phenylalanine• Threonine • Tryptophan • Valine
• Histidine (infancy only)
• 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
Incomplete Protein Foods
MeatMilkCheeseEggsFishChickenSoy beans
Baked beansPasta Potato RicePeasSpaghetti 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?
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 yrs4-8 yrs
Boys9-13yrs14-18yrs
Girls9-13yrs14-18yrs
1216
3149
2435
1420
4065
3545
NRVs for Protein – Adults
Age EAR g/per day
RDI g/per day
Men19-70 yrs>70yrs Women19-70yrs>70yrs
5265
3746
6481
4657
NRVs for Protein – Pregnancy & lactation
Pregnancy14-18yrs19-50yrs
Lactation14-18yrs19-50yrs
4749
5154
5860
6367
How much protein?
NRVs retrieved from Nutrition: The Inside Story
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 athletesSource: 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 foundin developing countries where there is a deficiency in the qualityand quantity of dietary protein.
Symptoms include wasted muscles, protuberant belly, brittle hair and failureto 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
Avoid eating all animal products and foods. Lacto-Vegetarian
Avoid meat and eggs, but include dairy products Lacto-Ovo Vegetarian
Avoid eating all animal products, but will consume milk, milk productsand 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 legumesor vegetables and legumes.
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.