nutrition Flashcards
important things about carbohydrates
most efficient energy source
classified as simple or complex
not all carbs are digested or absorbed at the same rate
Sugars mono vs disaccarides
monosaccharides or simple sugars (glucose) found mostly in fruits, syrups and honey
disaccharides are a combination of two monosaccarides (sucrose or lactose)
Starches
made up of long chains of glucose units (rice, potatoes, bread)
the body cannot use starches and many sugars directly from the food source
must be broken down during digestion and metabolism
where is glucose stored
as glycogen and in the liver and muscle cells
how much glycogen does the body store
a limited number (in liver and muscle cells) if extra, stored, it is converted to body fat
when inadequate glucose, what will the body use for energy?
protein
but the protein is then diverted from it own important function
important to have all essential food groups
what is glycolysis
process that breaks down glucose to produce energy
fiber - tell me some things about it
not digested by humans
not found in animal sources of food
forms the structural parts of plants
aids normal elimination by reducing the amount of time required for wastes to move through digestive tract
reduces risk of colon cancer and coronary artery disease
helps lower obesity, constipation, colitis, apppendicitis, diabetes
~ 25grams/day
soluble fiber
oatmeal, legumes, some fruit
bind to cholesterol and prevent its absorption which can reduce blood cholesterol levels
insoluble fiber
whole grain breads, bran cereals
lipids/fats
50% of canadians fat intake comes from two of the food groups
meat and alternatives and
milk and alternatives
functions of fats
supply energy define body shape insulation protect internal organs lubricates body surfaces vitamin carrier hunger depressor contribute to texture, taste, flavour and aroma to food
triglycerides (TA)
every triglycerides contains: one molecule of glycerol 3 fatty acids methyl group carboxylic acid group
sterols
part of compounds in the body
bile acids
sex hormones
found in plants and animal products
phospholipids
composed of glycerol 2 fatty acids phosphate group choline part of cell membrane found in eggs, liver, soybeans, wheat germ, peanuts act as emulsifier in mayonnaise, salad dressing, pudding
classification of fatty acids
number of carbon atoms
number of double bonds
position of first double bond
omega 6 fatty acid
linoleic acid essential for growth maintain integrity of skin and hair deficiency - dermatitis, skin lesions blood clotting
hydrogenation of fatty acids
changes a liquid to a solid
pros: protects against oxidation
alters the texture of foods
cons: makes PUFAs (polyunsaturated fatty acids) more saturated
changes the molecule from cis to trans fatty acid
linked to CVD
*can decrease the number of double bonds, some of the cis-double bonds are converte to trans double bonds
this results in high trans fat (which tends to be solid at room temperature
cholesterol is made where?
made in the body, from glucose and fatty acids in the liver
vitamin D is made from cholesterol in the body
used to make several hormones includes estrogen and testosterone
good cholesterol
HDL-C
bad cholesterol
LDL-C
plant sterol
found in corn, rye, wheat, seeds, nuts, legumes, vegetable oils - hydrogenated into margarine
consuming 1.3g/day of plant sterol can decreasetotal blood cholesterol and LDL-C
fat digestion system
mouth - lingual lipase
stomach - lingual and gastric lipase
small intestine - secretin, cholecystokinin, Bile (emulsifies fat), intestinal and pancreatic lipase
large intestine - fat trapped in fibre gets excreted
energy release from fat
adipocytes (fat cells) - site of fat storage - typically stored as triglycerides
mobilization- utilizing fatty acids is lipolysis
triglycerides are split into fatty acids and glycerol
LPL
lipoprotein lipase breaks down triglycerides from lipoprotein, producing glycerol and fatty acids
HSL
hormone sensitive lipase drives lipolysis (HSL found in adipocytes)
lipids are either stored in adipocytes or used for energy
metabolism of fats
beta-oxidation: breakdown of fatty acids to acetyl CoA
gluconeogenesis: the making of glucose from non CHO from TG and amino acids from proteins
how does the body adapt to insufficient glucose
by combining acetyl CoA fragments (derived from fatty acids to produce ketone bodies
ketone bodies are compounds produced during the incomplete breakdown of fat when glucose is no available
heatlth effects of fat
saturated fats in the diet raises blood cholesterol
hydrogenated foods contain trans fatty acids
trans- fatty acids in the diet increase LDL-C and decrease HDL-C
obesity can be a consequence of high-fat, high-kcalorie diets in excess of energy needs
replacing saturated and trans fats with MUFA and PUFA is most effective dietary strategy in preventing heart disease
functions of protein
provide structure: growth movement: contraction transportation: lipoproteins enzymes: digestion hormones: insulin antibodies: protection from infection fluid and electrolyte balance acid-base balance maintain pH energy : 4kcal/gram
all amino acids are composed of:
carbon, hydrogen, oxygen, nitrogen (some sulphur)
all amino acids have the same basic structure:
a central carbon (C) an acid group (COOH) a hydrogen (H) an amino group (NH2) R group ( makes one amino different from another)
9 essential amino acids
histidine threonine valine tryptophan isoleucine leucine lysine phenylalanine methionine
**cannot be make in the body- must be supplied by diet*
11 non-essential amino acids
alanine arginine asparagine aspartic acid cysteine glutamic acid glutamine lysine proline seine tyrosine
the liver makes the non essential amino acids
deamination
removal of the NH2 group
transmination
transfer of nitrogen
once the NH2 group is removed from the amino acid, nitrogen is transferred between amino acid and keto acids to produce non-essential amino acids
peptide bond
a bond that connects amino acids together
dipeptide: 2
trypeptide: 3
polypeptide: 4
oligopeptide: 4-9
digestion/absorption of protein
enzyme hydrolyzes a protein = protease
protein digestion begins in stomach
(CHO/fat digestion begins in mouth)
gastrin triggers the release of HCl
2 main functions of HCl
denatures protein (takes it apart) activates pepsinogen (gastric juice) into its active form called pepsin (breaks peptide bonds (shorter chain polypeptides and some free amino acids)
small intestine protein digestion
smaller polypeptides and amino acids to and release secretin: signals the pancreas to release bicarbonate into the SI to neutralize the stomach acid and to inactivate pepsin
cholycystokin: activated enzymes to further breakdown protein (trypsinogen to trypsin)
recommended protein requirements for top elite endurance athletes
1.6g/kg
top elite strength athlete: 1.76g/kg
kwashiorkor
pure protein deficiency