Fats Flashcards
Explain the functions of fat as a nutrient in the body (8)
Energy - It is the most concentrated source of energy with 1g providing 9kcal. This is more than any other of the macronutrients. This means that a large amount of energy can be consumed in a relatively small volume of food.
Storage - excess fat not immediately used as energy is stored in the adipose tissue where it has several. functions. These include acting as an energy reserve, fat in the apidose tissue under. skin acts. as a insulating. layer, helping prevent excessive heat loss from. the body, maintaining. body temperature. Fat store in apidose tissue around delicate organs such as the kidneys helps protect. them from damage.
Essential fatty acids - they are provided as they are not synthesised in the body, they are supplied by fats in the diet, they are essential to carry out functions such as the maintenance of cell membranes. and to. make hormone like substances.
Vitamins A E D K - adequate. intake is ensured, and they all have functions in the body, such as vitamin A protecting the cornea of the. eye.
What do you understand by the term trans fatty acids? (5)
These are polyunsaturates which have been artificially hardened by adding extra hydrogen during a process known as hydrogenation. The hydrogen atoms are on geometrically opposite sides of the double bond.
They are naturally present in low levels in meat and dairy products but are mostly used in the production of processed foods such as baked products and fat spreads. They are thought to have an adverse effect on health as they increase bad cholesterol and reduce good cholesterol which increases the risk of heart disease. They are also linked to an increased risk of rheumatoid arthritis. Therefore, it is recommended that trans fatty acids provide no more than 2% of our daily total food energy intake.
What do you understand by the term trans fatty acids? (5)
These are polyunsaturates which have been artificially hardened by adding extra hydrogen during a process known as hydrogenation. The hydrogen atoms are on geometrically opposite sides of the double bond.
They are naturally present in low levels in meat and dairy products but are mostly used in the production of processed foods such as baked products and fat spreads. They are thought to have an adverse effect on health as they increase bad cholesterol and reduce good cholesterol which increases the risk of heart disease. They are also linked to an increased risk of rheumatoid arthritis. Therefore, it is recommended that trans fatty acids provide no more than 2% of our daily total food energy intake.
Describe the effects of dietary fats on blood cholesterol levels (8)
Cholesterol is a soapy, waxy chemical found in all body tissues. It is formed around the bloodstream by proteins called lipoproteins. Two types of lipoprotein have been identified: HDL (High Density Lipoprotein) often referred to as good cholesterol as it helps to ferry cholesterol away from the arteries and other body tissues to the liver where it is broken down into bile. LDL (Low Density Lipoprotein) often branded as bad cholesterol, with increased risk of heart disease, as it tends to form fatty deposits on artery walls, increasing the risk of blood clots and
blockage.
The various fatty acids affect cholesterol levels differently. Saturated fats can increase total cholesterol and LDL cholesterol levels.
Monounsaturated fatty acids will lower LDL but raise or maintain HDL.
Polyunsaturated lowers total, with Omega 3 lowering LDL without affecting HDL and Omega 6 lowering both HDL and LDL. Trans fatty acids will lower HDL and raise LDL, thus increasing the risk of Coronary Heart Disease.
discuss the role of essential fatty acids in the diet (5)
Essential for the maintenance of cell membranes.
> Make hormone like substances such as prostaglandins and other eicosanoids which are involved in a number of functions in the body such as the blood and cholesterol regulation.
They are needed for metabolism, stimulation of smooth muscle contraction, effects on the immune system and nervous system.
D.
Evidence that eating EFA reduces the risk of death from heart attacks by decreasing the tendency of the blood to clot.
Idnetify 2 types of fatty acids we are advised to reduce in the diet and describe their effect s on blood cholesterol levels
Saturated fatty acids raise blood total cholesterol, especilly LDL (bad) cholesterol
Tranbs fatty acids lower good (HDL) cholesterol and raise bad (LDL) levels
Why us fat important jn the diet of an infant?
Fats are an important part of an infant’s diet because of their energy density - that is they provide a lot of energy in a relatively small volume of food and infants have high energy needs to meet growth demands.
Fats also provide essential fatty acids, especially omega 3 which are important for the development of the brain, vascular systems and retina in the early months of life. Finally fats will provide the fat soluble vitamins A and D required for growth.
name 3 food sources of trans fatty acids
spreads, cakes and fast food
Describe the structure of trans fatty acids
These are fatty acids with the hydrogen atoms on geometrically opposite sides of the double bond
Name two essential fatty acids
omega 3 and 6
state the current dietary reference value for saturated fat as a percentage of energy intake.
9kcal
describe the structure of a monounsaturated fatty acid
It is a long chain carboxylic acid; its molecule contains one double bond
