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What is cholesterol?
Cholesterol is a fatty substance (wax-like) produced by all animals -> it is not a fat
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What is cholesterol required for?
- cell membrane structure
- vitamin D and hormone manufacture
- digestion of fats -> used by liver to make bile acids
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What are sources of cholesterol?
eggs, prawns, butter, foods rich in saturated fats and trans-fatty acids
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Note about cholesterol:
- Plant foods do not contain cholesterol
- 3/4 of the body's cholesterol is produced by the body (body makes it itself -> made in the liver and intestines
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Where is cholesterol carried in the body?
through the blood by lipoproteins
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What is High Density Lipoprotein (HDL)?
- referred to as the good cholesterol
- removes cholesterol from arteries and takes it back to the liver
- prevents build up of fatty deposits on artery walls
- protects against heart disease (CVD - Cardiovascular Disease)
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What is Low Density Lipoprotein (LDL)?
- referred to as the bad cholesterol
- high LDL -> cholesterol tends to be deposited on artery walls
- causes fatty acid build up -> hardens and narrows arteries
- promotes heart disease (CVD - Cardiovascular Disease)
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How can one lower cholesterol?
- avoid eating foods high in LDL cholesterol. ie. saturated fatty foods and trans-fatty foods
- eating foods rich in carbohydrates and fibre
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Fact about cholesterol:
- saturated fats -> increase LDLs
- mono-unsaturated fats -> decrease level of LDL
- poly-unsaturated fats -> reduces cholesterol
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What are micronutrients?
They are vitamins and minerals which are needed in smaller amounts and their recommended daily intakes are usually measured in milligrams (mg) or micrograms (μg)
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Describe vitamins.
- vitamins are organic compounds that occur in small amounts in a wide variety of foods
- vitamins are classified as either:
- -> water soluble - required often as they are excreted daily in urine, faeces and perspiration. They are easily destroyed by light and oxygen as well as through poor storage, food preparation and cooking
- -> fat soluble - sturdier and are stored in the body in fatty cells, including the liver, adipose tissue and kidneys
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Describe minerals.
Minerals play a role in many chemical reactions within the body. Also form part of the structure of hormones, enzymes, vitamins and bones
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Describe these 4 vitamins functions, deficiencies, excess, food source and RDI
- Vitamin B12 (Cobalamin)
- Folate/Folacin/Folic Acid
- Vitamin C (Ascorbic acid
- Vitamin E (Tocopherols)
- Vitamin B12
- - Function: formation of red blood cells in bone marrow
- - Deficiency: increased chance of folic acid deficiency
- - Food Source: meat, milk and milk products, seafood, eggs
- - RDI: men and women approximately 2μg, babies under 12 months between 0.3μg and 0.7μg
- Folate/Folacin/Folic Acid
- - Function: metabolism of proteins and produce red blood cells in association with Vitamin B12
- - Deficiency: anaemia, sterility in males and females, and neurological diseases
- - Excess: vomiting and diarrhoea, undetected deficiency in Vitamin B12
- - Food Source: wholegrain cereals, avocados, milk and peanuts
- - RDI: men, women, children, and adolescents approximately 200μg, babies under 12 months between 50-75μg
- Vitamin C
- - Function: promote absorption of Iron and Calcium, supports Folic Acid and Vitamin E in their functions
- - Deficiency: poor resistance to infections, fatigue, irritability and depression, poor bone formation
- - Excess: Vitamin B12 deficiency may occur
- - RDI: men, women, children and adolescents approzimately 30mg, babies under 12 months between 25mg and 30mg
- Vitamin E
- - Function: protects red blood cells, protects fats and Vitamin A from being destroyed by oxidation, and assists Vitamin C in preventing the formation of carcinogenic substances in the digestive system
- -Deficiency: reduced protection from carcinogenic substances in the digestive system
- - Excess: weak muscles, nausea, Vitamin C deficiency
- - Food Source: wholegrain cereals, eggs, nuts, green vegetables
- - RDI: men, women, children and adolescents approximately 8mg and babies under 12 months 4mg
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Describe these 2 minerals, their functions, deficiencies, excess, food source and RDI
- Calcium
- Iron
- Calcium
- - Function: formation of strong bones and teeth -> needed in conjunction with P, Vitamin C and Vitamin D
- - Deficiencies: bone loss occurs, osteoporosis
- - Food Sources: Milk and products, tofu,almonds, sesame seeds, most breads, dark green vegetables and seaweed
- - RDI: pre-menopausal women, men and children 800mg/day and post-menopausal women 1000mg/day
- Iron
- - Function: forms part of haemoglobin protein which carries Oxygen around the body. When consumed with foods rich in Vitamin C, the absorption rate of iron increases
- - Deficiencies: decreased production of red blood cells, iron-deficiency anaemia and decreased capacity to exercise
- - Excess: problems in achieving and maintaining Fe balance due to difficulty in absorbing Fe from consumed food -> consume Fe without Vitamin C or with excess phylate, tea/coffee
- - Food Sources: meat and fish, offal meats, egg yolks -> haem, legumes, green leafy vegetables, nuts and seeds
- *Absorption rate increases when Fe consumed with foods high in Vitamin C (eg. citrus fruits, broccoli, pumpkin)
- - RDI: children and adolescents 10-13mg and menstrating women and girls 12-16mg due to monthly blood loss
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What is energy required for?
- 1. Basal metabolic activity - the minimum amount of energy required to keep your body functioning and hence keep you alive
- 2. Physical activity - energy required by muscles to enable you to move
- 3. Digesting, absorbing and using food - need energy for these processes. Referred to as the thermic effect of food
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Facts about energy:
- fat consumption: 20-30% of energy intake and saturated fat to only about 10% of this
- carbohydrates: approximately 45-65% of energy -> 10-15% maximum from simple carbohydrates
- minimum of 25mg in dietary fibre
- protein: one gram per kilogram of body weight per day or between 15-25% of total dietary intake
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How do you calculate BMR?
- for females = (bodyweight kg x 0.9 x 24 hours) x 4.184
- for males = (bodyweight kg x 1.0 x 24 hours) x 4.184
- total daily energy expenditure is a combination of BMR + energy used in physical activity + thermic effect of food (which depends on how much food you eat) -> thermic effect of food is usually 10% (multiply the total energy of food consumed by 0.1)
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How do you calculate BMI?
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Explain Malabsorption Syndromes
the difficulty in absorbing nutrients due to food intolerances/allergies
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What is Caeliac Disease?
- a permanent intolerance to gluten (protein found in wheat, rye, barely and oats)
- consuming gluten causes loss of villi in the small intestine ->needed for absorption of nutrients
- therefore decrease villi = nutrients (eg. protein, viatmins, minerals) not being absorbed
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What is Lactose Intolerance?
- unable to break down lactose in milk products (due to lack of enzyme lactase which digests lactose)
- therefore lactose reaches the bowl (large intesting) without being digested -> this attracts water and bacteria (lactase is fermented and this produces gas)
- *soy products are a suitable substitute: they contain no lactose, are high in calcium and are good sources of Vitamin D and phosphorus
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What are factors affecting basal metabolic rate (BMR)?
- gender - males have a higher basal metabolic rate than females, due to higher rate of lean activity body tissues compared to adipose tissues
- age - later years often see a decline in BMR due to less activity and reduced lean muscle tissue
- exercise - BMR is increased during any exercise and it remains high for several hours after intense and prolonged exercise. The more exercise a person does, the greater the lean active body tissue and an increased BMR
- hormones - certain hornonal conditions affect BMR. People with an overactive thyroid have a greater metabolic rate
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