Carbohydrates

Carbohydrates learning Goals

To learn the importance of Carbohydrates in the diet

To learn about the three groups of Carbohydrates

To learn about the main food sources of Carbohydrates

Carbohydrates

Carbohydrates are made up of three chemical elements: carbon, hydrogen and

oxygen

Hence they are often abbreviated as CHO

Carbohydrates

1g of carbohydrates provides

16 KJ

Carbohydrates are the body’s preferred energy source and

should make up 55% of our daily dietary intake.

Carbohydrates are divided into two main groups:

Sugars (Simple)Quick source of energy and simplest glucose

bonds (one=monosaccharide or two=disaccharide)

Starches (complex) Made up of long chains of glucose molecules

linked together (many=polysaccharide)

Sugars

Sugars are contained in the structure of foods such as fruits, vegetables, honey and milk.

Monosacharides• Fructose- In honey and fruit• Glucose- In honey and fruit

Disacharides • Maltose- In malt • Sucrose- In Cane Sugar• Lactose- In milk

Sugars

Refined sugars are the granulated sugars used in cooking or food processing. They are sometimes called ‘empty calories’ or

‘quick fix’ energy. For example a doughnut has lots of added sugar and doesn't contain

important nutrients.

Polysaccharides

Starches are long chains of glucose molecules contained in the structure of plants and are formed during photosynthesis. They are the cells where plants store their energy.

Root vegetables, legumes such as peas and beans and grain products such as bread, rice and pasta are high in starch.

Starches can be refined also during processing, removing nutrients and fibre. Good food sources are those that are wholegrain rather than white.

Cellulose forms the structure of plants and is often known as fibre.

Carbohydrate Digestion (moodle video)

All carbohydrates are broken down by the body into sugars or ‘glucose’ which is used for

energy. 

Simple Sugars are only short chains to begin with, having only one or two bonds (Monosaccharide or Disaccharides). The body does not need to work hard to break these short chains down and that is why they are converted to energy quicker.

Complex starches are long chains of glucose molecules that have many bonds. They are called polysaccharides and the body needs more time to break the long chains down. This is why they release energy slowly.

Carbohydrates>Glucose>Energy

• During digestion, starches and sugars are broken down into glucose to be used by the body.

• Excess glucose is stored in the liver as Glycogen and can be used when extra energy is needed and to help maintain a steady blood glucose level.

• If it is not used it is stored as Body Fat.

• When blood glucose levels drop the body responds by demanding food.

• When the blood glucose levels are high, the desire to eat is reduced.

Carbohydrates>Glucose>Energy

• It is insulin that allows glucose to enter the body’s cells• The absence of insulin results in abnormally high

blood sugar and eventually DIABETES.

Glycaemic Index• The blood glucose level is affected by the type of

carbohydrate food eaten.

• Some foods release energy slowly over a long period of time and provide sustained energy.

• Some foods release energy rapidly but do not provide sustained energy.

• Foods have been graded according to their effect on blood sugar levels, using a scale called the “Glycaemic Index”.

Suggest some foods for these Glycaemic Index classifications

HIGH GI- Fast energy release and hungry again soon after eating.

MEDIUM GI- medium energy release

LOW GI- Slow energy release and fuller for longer.

Which classification do you think is better for us?

Resistant Starches• Some starches are not digested. These are

called RESISTANT STARCHES.– Found In most carbohydrates but high in firm

bananas, roasted chickpeas, baked beans, boiled long grain white rice.

• Promote bowl movements as they stay in the large intestine. They attract water and soften faeces.

• Resistant starch is broken down by bacteria in the large intestine and is formed into beneficial fatty acids.

Dietary Fibre (non-starch polysaccharide)

Structural parts of plants called cellulose found in vegetables, fruits, grains and legumes

Humans cannot digest dietary fibre, but it is important to move waste material in the large intestine.

Fibres

• Dietary fibre is a type of carbohydrate that cannot be digested by our bodies' enzymes.

• Fibres are classified into two groups– Soluble Fibres- disolve in water to form a gel, ie.

Pectin from fruit, gums, some cereals

– Insoluble fibres- do not dissolve in water,

ie. Strings of celery and corn kernel skins

Soluble fibre includes gums and pectins. They are found in foods like fruit, oats, beans and barley. When it dissolves in water it forms a gel-like substance. Soluble fibre helps to:

– Support the growth of friendly bacteria needed to help maintain a healthy gut

– Reduce cholesterol absorption by binding to it in the gut

– Slow down the time it takes for food to pass through the stomach into the small intestine This helps slow down the absorption of glucose into the bloodstream and has the benefits of keeping you feeling fuller for longer, helping to control blood sugar levels, which are important for the management of diabetes.

Why the body needs soluble fibre

Insoluble fibre does not dissolve in water and is found in foods like wholemeal bread, wheat bran, vegetables and nuts.

– Insoluble fibre adds bulk to stools by absorbing water, and helps to keep you regular. It is important to increase your fluid intake as you increase fibre. Without fluid, the fibre stays hard, making it difficult to pass and causing constipation.

Why the body needs insoluble fibre

How much do we need?

• http://www.webmd.com/diet/fiber-health-benefits-11/truth-about-fiber

• https://www.youtube.com/watch?v=MvYLAIaGjUA

• Men- at least 38 grams per day• Women- at least 25 grams per day

Fibre Check

• Activity 1: List the foods you ate yesterday.

• Estimate the fibre content that you consumed using the handout.

• Modify your daily diet for yesterday to give some suggestions on how you could add more fibre to your diet.

• Activity 2: Modify the following meals/recipes to increase their fibre…