Micronutrients and performance Flashcards
macrominerals requirement
> 100 mg/day
Trace elements requirement
< 20 mg/day
Explain B vitamins for performance (water soluble)
- All 8 B vitamins are involved in energy metabolism.
- Primary role as co-enzymes in energy-producing pathways.
- Thiamine, riboflavin, B6, niacin, folic acid, and B12 are involved in nervous function and muscle contraction.
- B12 and folic acid are involved in nucleic acid synthesis
Rationale for increased B vitamin needs in active individuals
- exercises stress metabolic pathways that utilise B vitamins
- loss of nutrients in urine or sweat, increased turnover
- increased need due to training-induced biochemical adaptations
- increased demand for co-factors for mitochondrial enzymes
Does B vitamin status affect performance?
- sub-clinical single B deficiencies unlikely to affect performance
- combined depletion of thiamine, riboflavin and B6 resulted in 12% decrease in VO2max, 9% decrease in peak power
Does B vitamins supplementation improve performance capacity?
- not if the athlete has good vitamin status
- possibly if the athlete has poor vitamin status
Why is iron important for athletes?
- functional component of Hb and myoglobin
- key component of erythropoiesis
- energy production, cytochromes in electron transport chain
What is the prevalence of iron deficiency amongst athletes?
- 52% of female and adolescent athletes
- higher prevalence in endurance and sports with a high incidence of eating disorders
- male gymnasts, 45% prevalence
Name some risks factors for iron deficiency in athletes
- strenuous training
- sweat loss
- blood loss
- inadequate dietary iron intake and/or low nutrient bioavailability
How does low iron status affect performance?
Iron deficiency anaemia:
- reduced VO2max
-reduced task duration before the onset of fatigue
- poor concentration
- negative effects higher in less trained/during adaptation to training
Explain dilutional pseudo-anaemia (sports anaemia)
Reduction in iron content in an individual’s blood as a result of strenuous exercise
True or false
Mineral deficiency may impair performance if operating in sub-optimal state
True
When is necessary to supplement with iron?
- on low diets or periods of inappropriate food intake, e.g. female athletes with iron-deficiency anaemia
- during ultra-endurance events, addition of minerals to meal replacements may be recommended to compensate for sweat or urine loss
What are antioxidants?
Molecules that can be present in small concentrations that prevent or reduce the extent of oxidative damage due to other biologically relevant molecules.
Neutralise reactive oxygen species (ROS) to relatively less harmful by-products
What leads to a chain reaction creating more free radicals?
Donation of single electrons
Name some sources of ROS (reactive oxygen species)
- mitochondrial leakage
- skeletal muscle contraction
- muscle damage: neutrophils, monocytes
- enzyme systems
ROS are products of normal metabolism
Explain oxidative stress
disturbance of the oxidation-reduction balance in favour of oxidants, leading to a disturbance in redox signalling and control and/or molecular damage
Name some physiological stimuli (oxidants) for oxidative stress?
- radiation
- alcohol use
- smoking
- exercise
What is redox balance?
Balance between oxidants and antioxidants
Name some dietary (non-enzymatic) antioxidants
- vitamin A
- vitamin C
- vitamin E
- caratonoids (beta-carotene)
- polyphenols (red wine, tea, chocolate, scavenge free radicals)
- anthocyanins
Name some co-factors antioxidants
- Iron (catalase)
- Zinc, cooper (SOD)
- Selenium (glutathione)
Explain Vitamin C
- stabilises hydroxyl radical
- scavenges singlet oxygen
- reduces the oxidised form of Vit E
Which vitamin will impair exercise performance if taken in high doses?
Vitamin C
Safe advice for athletes for vitamins and minerals?
Aim for 5 per day to consume adequate Vitamin C, folate, magnesium, etc
