ASIN500 - Introduction to Nutrition - Lecture 3 - Carbohydrates

Flashcards about Carbohydrates

Monosaccharides

glucose, fructose, galactose

Disaccharides

sucrose , lactose, maltose

Polysaccharides

starch, cellulose, glycogen

Monosaccharides

Single sugar units.

Glucose

Found in fruits, vegetables, honey. Also known as blood sugar and used for energy.

Fructose

Found in fruits, honey, corn syrup (HFCS). Also known as fruit sugar.

Galactose

Found as part of lactose in milk.

Disaccharides

Two linked sugar units

Sucrose

glucose + fructose; table sugar; made from sugar cane and sugar beets

Lactose

glucose + galactose; milk sugar; found in milk and dairy products

Maltose

glucose + glucose; found in germinating cereal grains; product of starch breakdown

Polysaccharides

Many sugar units

Starch

long chains of glucose units (amylose – straight chains or amylopectin – branched chains) found in grains, vegetables, and legumes

Glycogen

highly branched chains of glucose units; storage form of carbohydrate in liver and muscle tissue

Dietary Fibre

Recommended intake is 25 – 30g per day

Soluble fibre

Include pectins, gums, mucilages and some hemicelluloses; lower blood cholesterol and rate of glucose absorption; found in fruits, oats, barley and legumes

Insoluble fibre

Include lignins, cellulose and hemicelluloses; decrease transit time through gut and increase fullness; found in vegetables, wheat and grains

Recommended minimum daily requirements for fibre

Women = 28g and Men = 38g

Blood glucose disposal

Skeletal muscle is a primary site of glucose disposal and storage

Hyperglycemia

High blood sugar. High levels of insulin – link with CHD. Increased risk of medical problems with prolonged hyperglycemia. May cause reactive hypoglycemia.

Hypoglycemia

Low blood sugar. Symptoms - lethargy, confusion, anxiety, poor concentration, pale, dizzy, headache, shaking. Can be life threatening!

Reasons for Hypoglycemia

Low energy or CHO intake, high activity levels, illness, stress, type I diabetes

Remedy for Hypoglycemia

Use sugars (High GI CHO) to increase blood glucose level

Glycemic Index (GI)

A ranking (0-100) given to carbohydrate foods that indicates the rate at which that CHO increases blood sugar compared to a standard (pure glucose or white bread)

HIGH GI

Foods increase blood glucose quickly

LOW GI

Foods increase blood glucose slowly and the response is more sustained

Factors Affecting GI

glucose vs fructose, type of starch (amylose vs amylopectin), cooking method / processing, fibre (soluble vs insoluble), fat and protein, acidity

CHO requirements

Vary greatly depending on gender, body size and tolerance

Minimum carbohydrate intake

80 – 100g per day

Carbohydrate requirements for minimal activity or light exercise

2 – 4g/kg/d

Prolonged CHO restriction

<50g per day can result in many adverse side effects

High sugar intake causes

tooth decay, obesity, elevated insulin and glucose leading to increased risk of platelet aggregation and CVD

High fibre intake leads to

improved control of blood glucose, reduced risk of bowel cancer, reduced risk of heart disease, healthier GI tract – beneficial bacteria

Increase fibre intake by

increasing fruit and vegetable intake and using wholegrain breads and cereals