SN Micronutrients

bethdrysdale94's version from 2017-05-21 16:41

Section 1

Question Answer
What are micronutrients?essential nutrients required in very small amounts for health
what are vitamins?organic micronutrients essential for a specific organism. cannot be synthesised by the organism and must therefore be obtained from diet
what are minerals?essential inorganic micronutrients, that include trace elements and macrominerals
history of vitamins - eye disorders eg night blindness and also scurvyeye diseases - liver juice or dietary liver. scurvy - feeding trials on british seaman, treated with limes hence "limeys"

Section 2

Question Answer
Can vitamins be synthesised in the human body?not without assistance
Vitamin Dsynthesised in skin from cholesterol with exposure to UV light
Vitamin Ksynthesised by some gut bacteria
Water soluble vitaminsB complex and C
Fat soluble vitamins ADEK

Section 3

Question Answer
main function: energy metabolismB complex
main function: antioxidantsA, C and E
main function: collagen synthesisVitamin C
main function: hormones synthesisvitamin C norepinephrine
main function: bone synthesisvitamins D and A
main function: blood clotting factorsvitamin K
main function: visual Pigmentvitamin A

Section 4

Question Answer
Whats the difference between minerals and trace elements?minerals required >100mg/day, trace elements required <20mg/day
whats special about minerals?metabolically essential and must be derived from diet
How many minerals and trace elements are there in total?15
What are the minerals?Ca, P, Mg, K, Fe, Na, Zn, Cl
What are the trace elements?Cr, Cu, F, I, Mn, Mb, Se (Chromium, Copper, Flouride, Manganese, , Selenium)

Section 5

Question Answer
Structure function of mineralsconstituents of bones and teeth - most abundant = Ca, P and Mg
Soluble salts Na, K, Cl, Mg and Caresponsible for body fluid osmolality and determination of ICF and ECF volume. Maintain normal heart rhythm, muscle contractibility, neural conductivity
Components of proteins - I, Fe, Cu, Zn and SeI = thyroxine. Fe, Cu, Zn and Se are components of enzymes and cofactors

Section 6

Question Answer
What are antioxidants?prevent or limit the damaging effects of free radicals in the body intra and inter cellularly
What are free radicals?atoms or molecules that have 1 or more unpaired electron - most are reactive oxygen species (ROS). OH-, O2-2
How are free radicals formed?intermediates in normal biochemical reactions. Phagocytes produce ROS which are used to kill invading pathogens. Neutrophils use ROS to degrade damaged cell debris.
What can cause normal cells to produce ROS?abnormal environments eg hypoxia, ionising radiation
Name several internal and external causes of free radical formationUV light, radiation, smoking, metabolism, air pollution (reacting with the Ozone, UV light), inflammation
What are the two types of antioxidant systems?enzyme and non-enzyme antioxidant systems
How do antioxidants work?remove the unpaired electron and then they are regenerated
Enzymatic antioxidantsSuperoxide Dismutase (SOD) (O2- > H202). Catalase (H202 > H2O+O2). Glutathione Peroxidase/Reductase (H2O2 > H2O)
Non-enzymatic antioxidants?Vitamin E = lipid soluble, protects membranes from oxidative damage. Vitamin C = water soluble, presents in aqueous components of body. Others include flavenoids and carotenoids.

Section 7

Question Answer
What is muscle fatigue?inability of muscle to generate force.
What causes muscle fatigue?multifactorial but radical production may play a role
How may ROS production cause muscle fatigue?ROS production increases in contracting skeletal muscle. Excessive ROS production induces oxidative damage to muscle proteins and reduces force production
What have animal studies shown about antioxidants and muscle fatigue?antioxidants protect skeletal muscle from damage and delay fatigue during prolonged submaximal exercise. no effect during high intensity.

Section 8

Question Answer
McKenna et al 2006: OverviewN-acetylcysteine (NAC) or Saline (control/CON) infusion prior to exercise, 45 mins at 70% VO2max then exercise to fatigue at 92% VO2max.
McKenna et al 2006: resultsNAC over a minute longer to fatigue than control
McKenna et al 2006: conclusionNAC prolonged exercise

Section 9

Question Answer
Is there sufficient evidence that more commonly used antioxidants can improve exercise performance in humans with adequate intake?no
What are the commonly supplemented anitoxidants in athletes?Vitamin E, C and Betacarotene - harmful or beneficial??
arguments for supplementation: rigorous ex. training increases ROSantioxidants suggested to protect muscle fibres. most common ones are not toxic supplements so can be taken in high doses without harm
arguments for supplementation: radicals promote fatigue in skeletal muscleNAC attenuates fatigue. Evidence used by supplement companies to promote supplementation of other sntioxidants
arguments for supplementation: poor dietary intakepoor diet, energy restriction, increased training load
arguments against supplementation: exercise increases oxidative stress, but no evidence this is damaging to healthexercise increases enzymatic and non-enzymatic antioxidants in skeletal muscles
arguments against supplementation: sufficient dietary intakesupplementation not required if intake is sufficient
arguments against supplementation: might impair skeletal muscle adaptation to exerciseROS possible signal to promote expression of numerous skeletal muscle proteins. antioxidant enzymes, mitochondrial proteins and heat shock proteins

Section 10

Question Answer
Gomez-Cabrera et al 2009: overview8 weeks endurance training. 1g/day vitamin C vs Placebo
Gomez-Cabrera et al 2009: resultsVO2 max increased less in Vitamin C supplemented group, 10% less
Gomez-Cabrera et al 2009: conclusionreduced expression of transcription factors associated with mitochondrial biogenesis
Powers et al 2011: based on the available evidence...we conclude that athletes should not use antioxidant supplements but should focus on consuming a well-balanced, energetically adequate diet that is rich in antioxidant-containing foods