Diet and Nutrition Flashcards
malnutrition
Physical condition resulting from inappropriate/ inadequate diet that either provides too much/too little of necessary nutrient
Negatively affects the quality of life and learning as well a death and disease status
Energy input affected by
DIET IN TERMS OF
Internal factors : hunger./appetite
External factors; social and psychological
Energy output can be divided into
heat and work
total body energy=
energy stored = energy stored + energy intake - energy output
% of energy available for work
50% of energy released in the body not available for work (heat: unregulated, thermoregulation)
Work subdivisions
energy storage, mechanical work, chemical work
Active transport of molecules (energy storage)
in/out of the body, between compartments, across membranes
Mechanical work
voluntary and involuntary movement of muscles
Chemical work
synthesis for growth and maintenance (tissues and cells)
short/long term energy storage (ATP, glycogen, fat)
BMR
minimum level of energy required to sustain vital functions
- measured at rest in a fasted state in a thermo-neutral environment
- measured as the heat produced or oxygen consumed per unit time
- expressed as the calories released/kg of body mass or /m^2 of BSA/h
Total Energy Expenditure
BMR + dietary-induced thermogenesis (production of heat) + physical activity
-estimated from BMR and PAL (physical activity level)
PAL
energy expenditure in 24h due to physical activity
EAR
estimated average requirement
for energy
BMR x PAL
Higher PAL =
more active
2 categories of nutrients
Macronutrients and Micronutrients
Macronutrients
Higher daily requirements
proteins, fats, carbohydrates
Micronutrients
Lower daily requirements
Vitamins (organic)- water soluble (not stored) and fat soluble (stored)
Minerals (inorganic): macrominerals, trace elements
Which is preferred in the body as a short term energy source
carbohydrate
Is bread a protein
MOST CERTAINLY NOT
2 types of amino acid
essential and non essential
Essential AAs
must be obtained via diet
Can’t be synthesised in the body
Non essential AAs
Synthesised by the body
What is the central carbon in a AA called
alpha carbon
Acetyl CoA
Made from fats/carbohydrates/proteins
Delivers acetyl groups to Krebs cycle
Releases stored energy in the form of ATP
Non energy related functions of proteins
Dietary proteins source of aas: essential and non essential
Aas required for synthesis of proteins: structural (collagens, keratins) and functional (enzymes, antibodies, receptors, hormones)
AAs precursors of other biomolecules: nucleotides, catecholamines, neurotransmitter (serotonin), some aas function as neurotransmitters
- formation of antioxidants
Non energy related functions of carbohydrates
Dietary carbohydrates provide monosaccharides for biosynthesis and modification of macromolecules:
- glycoproteins
- membrane glycolipids
- glycosaminoglycans
- proteoglycans
Dietary carbohydrate is a source of fibre:
- indigestible, structural polysaccharides derived from plants eg cellulose
- add bulk and thicken contents of GI tract
- slows digestion and absorption carbohydrates and fats: production of beneficial, short chain fatty acids by colonic microbiota
glycoproteins
sugar and protein
cell-cell interactions
immune system role- eg antibodies and major histocompatibilty complexes
hormones
eg secreted and intehral membrane proteins
glycolipids
stability of CSM and cell recognition
eg blood group antigens
glycosaminoglycans
long unbranched polysaccharides with a repeating disaccharide unit- has a amino sugar
GAGs
Proteoglycans
GAGs linked to a protein core
influences signalling in matrix
Some fats
triglycerides, sat fats, monounsaturated fats, polyunsaturated fats, trans fats
triglycerides
glycerol and 3 fatty acids
main constituents of natural fats and oils
Energy store in the body
Saturated fats
saturated with H’s
Solid at RTP
Incr levels of LDL
Monounsaturated fats
1 c-c double bond
liquids RTP
solidify when chilled
Polyunsaturated fats
more than one c-c double bond liquid at RTP solidify when chilled 2 groups: omega 3 and omega 6 fatty acids incr LDL levels
Trans fats
formed artificially by hydrogenation
raise HDL levels
contain c-c double bond, double bond is in a trans formation
found naturally in small amounts
Non energy related functions of fats
- dietary fats source of essential fatty acids; alpha linoleic acid (ALA) and linoleic acid (LA)
- dietary fats required for membrane biosynthesis: phosphoplipids glycolipids, sphingolipids and cholesterol
- Act as carriers for fat soluble vitamins
- Required for biosynthesis of steroid hormones
- Required for biosynthesis of lipid mediators: eicosanoids, phosphoinositides
- Required for biosynthesis of proteolipids: GPI anchored proteins eg enzymes, receptors
Micronutrients: Fat soluble vitamins
can dissolve in fats and oils
Absorbed in the body with fat and stored in the body’s fatty tissue
Micronutrients: vitamins and trace elements
- essential for growth, maintenance and repair
- required in small quantities
- participate in many metabolic/regulatory proccesses: endocrine signalling (hormones), intermediary metabolism (coenzymes and cofactors), function as antioxidants - highly reactive
Micronutrients: minerals
inorganic substances required in small amounts for the body to function
Important ones: Ca, Fe, Mg
Ca
most abundant mineral in the body: bones and teeth, intracellular signalling and regulation of metabolic processes
Fe
formation of haemoglobin
Binds to oxygen
Important cofactor in many other enzyme reactions
Important in the immune system
Metabolism of drugs and foreign substances
anaemia symptoms and signs
pallor tachycardia fatigue, tiredness and headache breathlessness angina cramp
Causes of anaemia
iron deficiency
vitamin B12 deficiency
Anaemia
not enough healthy RBCs to carry O2 to the body’s tissues
DRVs
dietary reference values
pop-based estimates of energy and nutritional requirements for different groups of healthy individuals
four DRVs
Estimated average requirement (EARs)
Reference Nutrient Intakes ( RNIs)
Lower Reference Nutrient Intake (LNRIs)
Safe intake
RNI used when issuing nutritional guidance
Obesity
incr risk of CVD, cancer and Type II diabetes
decr mobility, quality of life and lifespan
