Core Topic 1: Fundamentals of Human Nutrition

Overview of Topic 1

1.1 Humans need essential nutrients for good health:

Investigate why humans must include essential nutrients in their diet.

Analyse how macronutrients and micronutrients function and their relationship to optimal wellbeing.

Investigate the relevance of Acceptable Macronutrient Distribution Ranges (AMDR) and develop skills to compare percentage requirements.

Understand and investigate how foods can be combined to improve their nutritional status.

Macronutrients - Carbohydrates

Found in plants and created through the process of photosynthesis. When plants use energy from the

sun to combine CO2 and water from the environment to form carbohydrate.

Carbohydrates are made up of Carbon, Hydrogen and Oxygen; thus, carbohydrates are abbreviated as CHO.

Why do we need Carbohydrates?

The body requires carbohydrates to: Provide the body with

heat and fuel to perform daily activities (1g = 16kj)

Provide dietary fibre to stimulate the digestive system

The regulation of protein and fat use by the body

Carbohydrate Classification

Carbohydrates

Monosaccharide

Disaccharide

Polysaccharide

Monosaccharide

Simple sugars There are three forms of monosaccharides:

Glucose Most carbohydrates are converted to glucose by the

digestive system Easily absorbed and used for energy The body’s preferred source of fuel Sources include ripe fruits, some vegetables and honey

Fructose (fruit sugar) sources include fruit and honey

Galactose formed during the digestion of lactose (milk sugar)

Disaccharide

Disaccharides contain two monosaccharide units.

Disaccharides include: Sucrose (glucose + fructose)

Found in cane sugar, fruits and some vegetables

Lactose (glucose + galactose) Found in dairy products

Maltose (2 molecules of glucose) Found in germinating grain crops

Investigation Skills

1. Name the graph.2. Interpret the findings

Polysaccharide

Monosaccharides can be joined together in long chains called polysaccharides.

Polysaccharides include: Starch

Found in cereals including wheat, rice and corn, cereal products including rice and pasta and vegetables including potato and peas.

Glycogen Stored in the liver and muscles Can be converted back to glucose

Polysaccharides

Pectin (soluble) Found in seeds, pith and peel

of fruits and vegetables. Digested by intestinal

bacteria. Attracts water and turns to

gel during digestionMay help reduce cholesterol Allows nutrients to be

released more slowly Contributes to a feeling of

satiety

Polysaccharides

Cellulose (dietary fibre – insoluble) Forms in the cell walls of

plants Partly digested

Adds bulk to the stoolAppears to help foods pass

quickly throughthe stomach and intestines

Contributes to a feeling of satiety

How much Carbohydrate?

1g of carbohydrate yields 16kj of energy. 45-65% of the total daily energy intake

should be from Carbohydrates. For example if the total energy intake is 8,000kj, then

3,600-5,200kj should derive from carbohydrates.

Carbohydrate Deficiency and Excess

Symptoms of deficiency Symptoms of excess

• Fatigue • Inability to exercise (no glycogen)• Headaches • Fainting • Lack of vitamins and minerals • Low dietary fibre intake – constipation • Protein depletion

• Dental caries (decay or cavity) build up of plaque, which sticks to acids in our mouth. The acid eats away at the outermost layer of the tooth called the enamel.

• Weight gain – increase in adipose tissue

Dietary Fibre

Fibre is grouped into two types: Soluble – digested by intestinal bacteria

legumes, oats, barley and fruits Insoluble –partly digested

Vegetables, grains, cereals and seeds

DigestibleSoluble

IndigestibleInsoluble

Why is Fibre Important?

Fibre is important in the diet because it: Slows down initial digestion for nutrients to be

released into the body slowly; thus, the absorption of vitamins and minerals is maximised.

Helps produce soft, bulky stools, which are easy to expel from body.

Provides a feeling of fullness in the stomach – thus reduces obesity.

Increases the transit time of stools through intestines; thus, prevents constipation, diverticular disease, bowel cancer, haemorrhoids and potentially varicose veins.

What is the graph depicting?

1. Name the graph.2. Interpret the results.

Why is Fibre Important?

Fibre is important in the diet because it: Slows down initial digestion for nutrients to be released

into the body slowly; thus, the absorption of vitamins and minerals is maximised.

Helps produce soft, bulky stools, which are easy to expel from body.

Provides a feeling of fullness in the stomach – thus reduces obesity.

Increases the transit time of stools through intestines; thus, prevents constipation, diverticular disease, bowel cancer, haemorrhoids and potentially varicose veins.

The Glycaemic Index (GI)

‘The speed at which a carbohydrate food breaks down into glucose has been studied and the foods have been ranked.’ (Queensland Government 2011)

The amount and type of sugar in a food will impact a food’s GI.

Glycaemic Index (GI)

Low = < 55% Intermediate = 55-69% High > 70%

Milk Weet Bix French friesYoghurt Brown Rice White breadNuts Soft drinks Jelly BeansBeans Brown rice Water melonPasta Sucrose Rice crackers

Glycaemic index (GI)

Low GI diets:help diabetics control

glucose tolerancecan reduce total

cholesterol and triglyceride levels, increase HDL, reduce blood clotting and risk of CVD

are more filling and can aid wait control

Structure of a Extended Response Question

Usually written in three of four parts. Ensure you address each dot point.

This section must be written in continuous prose. NO DOT POINTS !

Definitions should be given where possible. Give yourself time to structure your response.

Use relevant explanations and examples to support your response.

Extended Response Question

Polysaccharides are better for us than monosaccharides and disaccharides. Define monosaccharides, disaccharides and

polysaccharides. Discuss the significance of polysaccharides for human

beings. Outline concerns if a person does not consume

sufficient Polysaccharides. Outline dietary strategies to boost one’s intake of

polysaccharides.