dietary factors affecting CVD
our choices in food, particulary the type and quantity of high-energy foods can increase or decrease our risk of developing cardiovascular disease.
carbohydrates, lipids (fats and oils) and proteins are constituents of our food which store energy.
traditionally energy is measured in calories (one calorie is the amount of heat energy needed to increase the temperature of 1cm3 of water by 1 degree celceus)
food labels normally display units of 1000 calories , called kilocalories ( also called Calories with a capital C)
units for energy are joules J , 4.18 joules = 1 calorie.
the Kilojoule ( 1Kj = 1000 calories ), is used extensively in stating the energy conents in foods
the term carbohydrate means hydrated carbon.
most people are used to sugar and starch being classed as carbohydrates, but in fact the term covers a large group of compounds
monosaccharides are single sugar units which usually have 3-7 carbon atoms, but most commonly 6. for example glucose, galactose and fructose all have 6 carbon atoms and are known as hexose sugars.
a hexose sugar molecule has a ring structure formed by 5 carbons and an oxygen atom: the 6th carbon is positioned above or below the ring. the carbon atoms are numbered, staring with 1 on the extreme right of the molecule. the side branches project above or below the ring and their position determines the type of sugar molecule and its properties.
glucose is important as the main sugar used by all cells in respiration.
starch and glycogen are polymers made up of glucose sub units joined together.
when starch or glycogen is digested, glucose is produced. this can be absorbed and transported in the bloodstream to cells.
Galactose occurs in our diet mainly as part of the disaccharide sugar lactose. which is found in milk.
comparing the molecule to glucose the -OH group coming off carbon 1 and 4 is switched.
Fructose is a sugar which occurs naturally in fruit, honey and some vegetables.
its sweetness attracts animals to eat fruits and so helps with seed dispersal.
more monosaccharide info.
monosaccharides provide a rapid source of energy.
they are readily absorbed and require little or, in the case of glucose, no change before being used in cellular respiration. glucose and fructose are found naturally in fruit, veg and honey.