Minerals Flashcards
what are minerals?
Dietary element essential to life process
what diseases are associated with inadequate intake?
Cancer
Anaemia
Diabetes
Hypertension
Osteoporosis
mineral requirements - macro
Macro mineral
> 100mg / day
Ca, Cl, Mg, K, P, Na, S
mineral absorption
Some minerals = limited absorption
Calcium, Iron (Haem and non Haem)
Excess can be harmful / impair absorption of other nutrients
Ca - Fe and Zn
Zn - Cu
Moderate excess - kidneys - excrete
Na, K, Ca, CL, PO4
Haem - 10-30% - absorbed better
Non haem - 2-10% - vegetarians -
Calcium - 30% absorbed
Help absorption of iron if taken with vitamin C
what is the role of iron in the body?
Oxygen transport and utilisation
Component
Others
RDA
Physical health and mental wellbeing
Carry oxygen from lungs to rest of body
Important to maintain healthy immune system
Energy production - in several enzymes imp for energy production - cytochromes
Haem = meat, non = plants
iron stores
Ferritin
Liver, spleen and bone marrow
- Soluble ferritin
- transferrin
Stored with ferritin
iron depletion
Normal Ht and Hb
Serum ferritin <30
Normal transferrin sat
Common in athletes
No performance effect
iron losses with ex
Exercise in heat can lead to sweat rate of 2 L per h
Thus, 2 h of exercise results in 4 L sweat loss (0.3-0.4 mg Fe per litre of sweat)
1.2 mg Fe loss
Not all dietary iron can be absorbed in the gut (25%?)
Need more?
Large proportion lost
RBCs break when running
Increased demand in form of myoglobin as well for athletes
sodium
Maintain normal body fluid balance, osmotic pressure and blood pressure
Sodium lost in sweat can vary between 500 to 1800 mg/L
Take in too much salt - pull water out of cells - maintain homeostasis
Amount lost varies depends on indv
Issues with endothelial elasticity - how well vessels expand and contract, abnormal ion handling - pumps skewed, issues with hypertension due to nitric oxide
what happens if you have too much sodium
increase in extracellular fluid volume as water is pulled from cells to maintain normal sodium concentrations.
related to hypertension
RDA sodium
2.4g (6g salt)
zinc
Energy production
Macronutrient metabolism
Enzymes - LDH ADH
Nucleic acid
Hormones
Protein synthesis
Wound healing
Co factor in energy metabolism
Required for normal cell replication, immune function, wound healing and in some hormones
Alcohol dehydrogenase - need zinc to help break down alcohol - fat before - keep ADH in contact with alcohol - less quickly in bloodstream
Growth, thyroid hormones and insulin
Higher in slow twitch fibres than in fast
Changes in zinc in diet will most likely affect bonze zinc
95% stored in tissues - 5% blood
zinc and appetite
Zn intake within some groups of athletes is considerably less than rda (11 and 8 mg/day for m and f)
Prolonged exercise may result in significant losses of Zn in sweat (and urine)!
Role in appetite regulation.
Oral zinc supplementation is effective in restoring normal eating behaviour and body weight in patients suffering from anorexia
nervosa
High incidence of eating disorders in gymnasts
Involved in anorexia nervosa - effective in restoring normal appetite behaviour
Endurance runners - weight category sports
magnesium
Essential cofactor of enzymes involved in energy metabolism.
Mg is also required for maintenance of electrical potentials in
muscles and nerves
Dietary sources
Too much fibre
Vitamin D
Over 300 enzymes
Needed for protein synthesis, ox carbs, glycolytic pathways
Increased mg for pregnant/lactating
magnesium too high/low?
RDA magnesium
Mild Mg deficiency - period of heavy training, particularly in warm environment
Mg deficiency
- Neuromuscular abnormalities, muscle weakness, cramps and structural damage of muscle fibres
- Low calcium and potassium
- Mood
Too high = poss diahorrea
calcium intake and osteoporosis
Osteoblasts and osteoclasts are responsible for bone modelling
Turnover – calcitonin and parathyroid hormones
Inadequate Ca - Osteoporosis
Ca intake of 1000-1200 mg/day is recommended to protect against osteoporosis
Dietary sources
Vitamin D is important for healthy bones
Vitamin C imp in bone formation
development of osteoporosis
(low) estrogen levels
Alcohol
Caffeine intake
Family history
Gender (female)
Amount and type of physical activity
Resistance type exercise
calcium intake for athletes: Cause for concern?
Amenorrhea / oligomenorrhea
Contributing factors:
low body fat
low energy intakes
high physical activity
mineral status of an athlete
Caution - dietary intakes
Assessment is difficult
Plasma mineral concentration does not always give accurate reflection of total body stores of mineral (e.g. zinc)
mineral status and ex
Exercise can decrease plasma concentrations of minerals
Heavy training likely to increase requirement
Iron
Zinc
Magnesium
Sodium
athletes at risk of inadequate iron and calcium intake
Young athletes
Female athletes
Low energy intakes (<10 MJ/day)
Weight category sports
Vegetarians
Athletes training in hot climates
iron deficiency
Most widespread deficiency
Tiredness, feel cold, more infections, impaired cognition
Impact on performance
Depletion - not enough stores for what you’re doing
zinc and eating disorders
Zinc in protein rich foods - oysters - nuts and legumes
how much of the body mass consists of 22 minerals?
4%
women and minerals
women who train intensely but cannot match energy intake to energy output reduce body weight and fat to point that may adversely affect menstruation
often show advanced bone loss at early age
restoration of normal menstruation doesn’t totally restore bone mass
association between muscular strength and bone density
raises likelihood of using strength testing of postmenopausal women as clinically useful tool to screen for osteoporosis
how many American women of child-bearing age suffer from dietary iron deficiency
40%
neg affects aerobic ex perf and ability to perf intense training
the DASH eating plan
lowers blood pressure in some indvs to same extent as pharmacologic therapy and often more than other lifestyle changes
micromineral requirements
<100mg / day
Fe, Zn, Cu, Cr, Co, Mn, I, F, Mo, Se
ultra trace requirements
<1mg day - very small amount
Nuts, milk, fruit, seeds
Not in processed food
what is iron a component of?
Haemoglobin - 75% of iron in form of Hb
Myoglobin
Cytochromes
iron stored
Stored (25%)
1000mg - males
300-500mg - females
RDA of iron
8-10mg (M) and 18mg (F)
Females need more due to menstrual cycle
sodium intake in USA
4.5 g per day!
total amount of zinc in body
2g and most of this is present in muscle (60%) and bone (30%).
dietary sources of magnesium
seafood, nuts, fruits, milk, etc
RDA magnesium
400-420 mg (m) and 310-320 mg (f)
dietary sources of calcium
dairy products, beans, canned salmon, dark green leafy vegetables and peas
soluble ferritin role
released from cells into plasma in direct proportion to how much ferritin in cells - indicative of iron status - amount stored
transferrin role
transports from food to tissues - how much iron just eaten - amount released
why is assessment of mineral status difficult?
differences in bioavailability of trace element in various foods
not all foods have been analysed for mineral composition
osteoblasts
Calcitonin with high calcium
osteoclasts
breakdown of bones - demineralisation –> osteoporosis
