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 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 energy15-25% 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 – AdultsAge EAR

g/per dayRDI

g/per dayMen19-70 yrs>70yrs Women19-70yrs>70yrs

5265

3746

6481

4657

NRVs for Protein – Pregnancy & lactation

Pregnancy14-18yrs19-50yrsLactation14-18yrs19-50yrs

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 0.8-1.0Elite male endurance athletes 1.6

Moderate-intensity endurance athletes (a) 1.2

Recreational endurance athletes (b) 0.8-1.0

Football, power sports 1.4-1.7Resistance athletes (early training) 1.5-1.7

Resistance athletes (steady state) 1.0-1.2

Female athletes ~15% lower than male athletesTable 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 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.

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.