Micronutrients

Question 1

Name and describe the two types of miconutrients

Answer 1

vitamins: organic nutrients which are essential for an organism
cannot be synthesised by that organism

minerals: inorganic nutrients which include trace elements and macrominerals

Question 2

which twp vitamins can the body synthesise and where are they synthesised from

Answer 2

Vit D: skin

Vit K: gut bacteria

Question 3

Name the main functions of vitamins and which vitamin helps with each function

Answer 3

1) energy metabolism: B complex helps with coenzymes of the krebs cycle
2) antioxidant: A,C,E

3) synthesis of body componants:
      C = collogen 
       A = bone and visual pigment 
       K = blood clotting factors 
       D = bone

Question 4

what are the daily requirements for minerals and trace elements

Answer 4

macrominerals = > 100 mg/day

trace elements = <20 mg/day

Question 5

Name the main functions of minerals and give examples of which minerals are involved in this function

Answer 5

structure: e.g constituants of bone and teeth (Ca, P)
fucntion: e.g elecrolytes for maintaining osmolaltity

regulation: e.g iodine in thyroxine
other elements also make up parts of proteins or act as cofactors

Question 6

Name three common ROS found in the body

Answer 6

Superoxide
Peroxide
Hydroxyl radical

Question 7

Name some endogenous sources of ROS

Answer 7

aerobic respiration

other biochemical reactions

WBC produce them for phagocytosis

produced by cells when exposed to hypoxia or ionising radiations

Question 8

Name some external sources of ROS

Answer 8

Air pollution
smoking
UV light
radiation

Question 9

Name three important antioxidant enzymes

Answer 9

Superoxide dismutase

Catalase

Glutathione Peroxidase

Question 10

what two vitamins act as antioxidants and what structures do they protect

Answer 10

C (present in aqueous structures)

E (membranes)

Question 11

How are free radicals involved in muscle fatigue

Answer 11

increased ROS production during muscle contraction

causes oxidative damage to muscle proteins

reduces force production

Question 12

What effect was shown when infusing subjects with N-acetylcystine before exercise

Answer 12

vs saline infusion = longer time to fatigue with antioxidant

Question 13

what are the arguments against using antioxidant supplementation in athletes

Answer 13

is little evidence of benefit for antioxidants other than N-acetylcystine

should have adequate amounts if consuming a sufficient diet

evidence that large amounts can be detrimental to performance

no evidence that oxidative stress is harmful to health

exercise training naturally increases enzymatic and non-enzymatic antioxidant production

may impair adaptation bc ROS is possibly a signal to promote expression of skeletal muscle proteins

Question 14

what are the arguments for using antioxidant supplementation in altheletes

Answer 14

rigorous training = ROS production, supplementation can protect muscle proteins

mostly non-toxic unless taken in v high doses

radicals promote muscle fatigue and N-acetylcystine attenuates fatigue

can be used in case on inadequate dietry intake

Question 15

give evidence suggesting that vitamin C supplementation may impair adaptation

Answer 15

placebo vs 1 g/day supplement over 8 weeks of endurance training

placebo = 22% increase in VO2 max vs 11% in supplement group

thought to be due to downregulation of expression of transcription factors associated with mitochondrial biogenesis due to supplementation

Question 16

what conclusions have been drawn from the available data about using supplements in athletes

Answer 16

limited data to support recommending use

need for caution when using high levels of antioxidants

should instead focus on having a well balanced diet

Question 17

give arguments supporting the use of vitamin D supplements in athletes

Answer 17

Many athletes may be deficient

especially those with pigmented skin, indoor training or training at high latitude

some evidence that it can improve athletic performance in those who are deficient

Question 18

give arguments against the use of vitamin D in athletes

Answer 18

limited evidence that it is ergogenic

risk of toxicity

large individual variation in response to vitamin D supplementation

Question 19

from readings, what is the proposed mechanism for why N-acetylcystine supplementation delays fatigue

Answer 19

prevents ROS supression of Na/K ATPase and therefore attenuates plasma increase in K concentration