week 2 (async)- overview of basic nutrition Flashcards
(35 cards)
bomb calorimeter
- used to measure energy in food
- food is completely burned in a container that is surrounded by water
- energy is released as heat, raising the water temperature
- how much the temperature is raised reflects how much energy has been released
1 kcal = amount of energy required to raise 1kg of water by 1°C
role of energy in the body
a) basal metabolism: energy required to maintain normal body functions while at rest (60-75% of kcal needs)
b) physical activity: energy needed for muscular work (most variable need)
c) dietary thermogenesis: energy used to ingest and digest food (ie. peristalsis)
body fat (energy requirements)
less metabolically active, accounts for <20% of energy used for basal metabolism
brain, liver, kidneys and muscle (energy requirements)
more metabolically active, accounts for 80% of energy used for basal metabolism
digestion
food is broken down via chemical or mechanical digestion, into substances that can be absorbed by the body
digestive system
location and coordination of digestion, 25-30 ft long muscular tube
absorption
- process by which nutrients and other substances are transferred from the digestive system into body fluids for transport throughout the body
- most carbohydrate, protein and fat is absorbed within 30 minutes of the chyme reaching the SI
energy content of macronutrients
fat (9 kcal/g), carbs (4 kcal/g), protein (4 kcal/g)
where does energy come from?
fat, carbs, protein and alcohol
carbs
includes simple sugars, complex carbs and fibre
role of carbs
a) energy: usually 40-80% food intake, body can only use glucose for energy
- adequate intake prevents protein breakdown
b) provides taste and sweetness
staple foods
- eaten regularily, in relatively large amounts
- they cannot supply all nutrients needed
- maize, rice and wheat provide 60% of world’s food energy
simple sugars
a) monosaccharides: no breakdown required
ie. glucose, fructose, galactose
b) disaccharides: must be broken down into monosaccharides before being absorbed
ie. sucrose (glu + fru), maltose (glu x2), lactose (glu + galac)
canadian sugar intake
- we get 21% of kcal from sugar
- kids (1-8) get most of their sugar intake from milk, fruit and fruit juice
why is it advised to add sugar to food in areas of food scarcity?
provides more energy and sweetness to bland food
complex carbs
a) starches: glucose molecules linked together
b) glycogen: storage form of glucose in liver muscle
c) dietary fibre: polysaccharides that can’t be digested by humans
famine foods
- foods that would otherwise be considered inedible but are eaten during times of extreme food scarcity
- can help ease hunger pains and maintain routine
ie. corn husks, leaves, moss, dirt, paper, tulip bulbs
role of protein
a) structural component for muscles, connective tissue, organs and hemoglobin
b) basic component of enzymes, hormones, transporters and the immune system
c) maintains and repairs protein-containing tissues
d) last resort energy source
amino acids
total of 20 different aa, 9 of which are essential (must be obtained in the diet)
where is protein found in the body?
half in muscle and the remainder in skin, collagen, blood, enzymes and immunoproteins
assessing adequacy of protein intake
quantity and quality
how much protein should we consume?
- children (1-3) need 5-20% of total kcal
- adults (19+) need 10-35% of total kcal
- requirements increase in the case of infections, burns, fever, surgery, pregnancy, breastfeeding and growth/development
protein quality
a) complete proteins: contain all the essential aa in adequate amounts
ie. meat, dairy eggs
b) incomplete proteins: deficient in one or more essential aa
ie. legumes, peanut butter, grains
limiting aa
the aa in an incomplete protein that is present in the least amount relative to the requirement for that amino acid
