intro to energy and nutrients Flashcards
FAT - FUNCTIONS
Energy source
Energy store - as largest energy store in body
Cell membranes (phospholipids - these are fats)
Supply essential nutrients
Precursors for hormones - eg sex hormones are steroid hormones that need a fat source to be synthesised adequately
Improve palatability
FAT - SOURCES
Main type of fat is triglycerides.
Triglycerides contain 3 fatty acids.
Fatty acids can be saturated or unsaturated.
Triglycerides consist of a mixture of fatty acids.
Carbohydrate - functions
Energy source – for immediate use and stores.
Glucose main energy source.
Part of RNA (ribose) and DNA (deoxyribose).
Integral feature of many proteins and lipids (e.g. glycoproteins), especially in cell membranes.
Carbohydrate - sources
Large part of energy in human diets.
Mainly obtained from plant material.
Cereal products, vegetables, fruit, nuts.
Milk and milk products.
Sugars in manufactured foods, e.g. sweets, cakes, drinks, many breakfast cereals.
role of nutrients
protein, fat, carbs, and alcohol provide energy
explain 1 calorie
amount of heat required to raise temperature of 1g of water by 1C.
explain 1 kilocalorie (1 kcal or 1 Calorie)
= amount of heat required to raise temperature of 1kg of water by 1C.
convert KJ to J
1 kilojoule (kJ) = 1000 J = 103 J
convert 1 MJ to J
1 megajoule (MJ) = 1,000,000 J = 106 J
convert 1Kcal to KJ
1 kcal = 4.184 kJ
convert 1KJ to Kcal
1 kJ = 0.239 kcal
explain the principles of energy balance
the energy from our energy intake circulates in the blood stream and some of it is stored, excreted, or released as energy expenditure. 60% of energy expenditure goes towards BMR (basal metabolic rate = how much energy our tissues etc use up. it varies daily, but less than the following 2, 10% towards dietary and cold induces thermogenesis (heat production), and 15-30% towards physical activity
what is energy is foods present as
a mixture of energy yielding nutrients.
explain food energy densities
Different foods have different energy densities.
low energy density foods have high water content, and high energy densities have low water content
how much Metabolisable energy per gram does fat produce
37JK or 9 Kcal
how much Metabolisable energy per gram does protein produce
17 KJ or 4 Kcal
how much Metabolisable energy per gram does carbs produce
16KJ or 3.75 Kcal
how much Metabolisable energy per gram does alcohol produce
29KJ or 7 Kcal
how many KJ are in 1Kcal
4.184
how many Kcal are in 1 KJ
0.239
how do you work out % of energy from fat, protein, carb and alcohol calculation
you times the NO. grams of fat for example by fats Metabolisable energy per gram, to work out the fat energy in KJ. and then divide that by the persons whole KJ of energy from their diet and times that by 100, to get the % of energy.
In a diet providing 8000 kJ of energy and 94 g of fat…
Fat provides 94 x 37 = 3478 kJ energy.
Fat intake = (34788000) x 100 = 43% energy.
what sources does food energy come from
fat, protein and carbs
what sources does total energy come from
fat, protein, carbs and alcohol
what are vitamins
Organic substances or groups of related substances found in foods which have specific biochemical functions in the body and are required in very small amounts.
vitamins are obligatory
what are minerals and trace elements
Inorganic elements with a physiological function in the body.
Must be supplied in the diet.
Minerals required in milligrams per day (mg/d).
Trace elements required in micrograms per day (µg/d).
Iron requirement is 5-15 mg/d but sometimes called trace element.
examples of minerals
Calcium
Chloride
Fluoride
Iron
Magnesium
Phosphorus
Potassium
Sodium
Sulphur
examples of trace elements
Boron Selenium
Chromium Tin
Cobalt Vanadium
Copper Zinc
Germanium
Iodine
Manganese
Molybdenum
Nickel
