Proteins - essential for growth and repair of body tissues
Fats - source of energy, insulation, etc.
Vitamins - play important roles in chemical processes inside cells. Water soluble or Fat soluble.
Minerals - inorganic elements, essential for normal functioning of the body
Water - transports substances around the body
Fibre - indigestible part f food needed for healthy digestive system
Correct proportion of the three macro nutrients - those needed in large amounts
- 57% carbohydrates
- 30% fats
- 13% protein
Different people need different amounts of food depending on their, age, level of activity and state of health e.g. pregnancy
Malnutrition: unbalance diet - having too much is as bad as not having enough.
Biggest form of malnutrition is obesity.
Body Mass Index over 30 is classified as obese and a condition where excessive fat deposits impairs health.
Obesity can lead to:
- Cancer
- Type 2 diabetes
- Coronary heart disease
It is linked to: Gall stones, osteoarthritis, high blood pressure
Diet and Coronary heart disease
- CHD = coronary heart disease
- a result of atherosclerosis = deposition of fatty substances in walls of coronary arteries
- narrows size of lumen
- restricts blood flow to cardiac muscle
- oxygen starvation
- Diet related risk factors
- unbalanced diet
- diet high in saturated fat (animal fat)
- high salt intake
- low fibre/fruit/vegetables
- obesity
- heavy alcohol consumption
- Salt
- Excess salt decease water potential
- more water in blood stream
- increase blood pressure
- hypertension
- damages inner lining of arteries first stage of atherosclerosis
- Lipids
- Animal fats = saturated fats - more harmful
- Plant oils = unsaturated fats
- Polyunsaturated fats are beneficial to health e.g. olive oil
- Cholesterol
- found in cell membrane and skin
- use to make
- steroid sex hormones
- bile
- not soluble in water
- cholesterol is transport in the blood in form of lipoproteins
- Lipoproteins are made in the liver to transport cholesterol
- Low density lipoproteins - LDL
- Deliver cholesterol to tissue (tissues cells have receptor sites on cell surface membranes)
- atherosclerosis
- >3mmol dm^-3 is dangerous
- High density lipoproteins - HDL
- Removes cholesterol from tissues to liver (liver cells have receptor sites on cell surface membraneto which HDL's bind)
- reduces atherosclerosis
- <1mmol dm^-3 is dangerous
- Saturated fats decreases activity of LDL receptors
- less LDLs removed from blood
- deposited in artery walls = atherosclerosis
- Polyunsaturated fats increases activity of LDL receptors
- decreases concentration of LDLs in blood
- Mono aturated fats removes LDLs from blood
- Prevention of CHD through diet
- low in saturated fats
- high in polyunsaturated fats and monosaturated fats e.g. oily fish
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