Minerals
and Sport Performance
Minerals
l
Inorganic
elements found in nature
l
From nutrition
perspective
l
Elements
essential to life processes
l
Origin is from
soil
l
Serve 2 of 3
basic functions of nutrients in foods
l
Building
blocks for body tissues (bones, muscles, etc.)
l
Components of
enzymes (metalloenzymes) which are important in regulating metabolism
l
These include
ions (electrolytes)
l
Do not provide a
source of caloric energy
Essential Elements and Minerals
l
Of all the elements in the periodic table, only
25 are currently known to be essential to humans
l
5 of these elements which make up CHO, Fat, and
Protein + Water account for 96% of body’s weight
l
These elements are hydrogen, oxygen, carbon,
sulfur, and nitrogen
l
The remaining 20 minerals compose less than 4%
of the body weight but are equally important
l
National
Academy of Sciences has established
DRI’s (Dietary Reference Intakes) for 15 of these minerals
Minerals and Sport Performance
l
How do
deficiencies or excesses of minerals influence performance?
l
Deficiencies
occur in stages:
l
Preliminary
§
Low-calorie diets
may reduce needed mineral intake
§
Note: RDA for iron
is 10 times amount needed by body, but this is due to fact that only 10% is
absorbed
l
Biochemical
§
Lack of
significant mineral intake observed in weight-control sports; this may make
athletes sluggish in response high level of performance
l
Physiological
§
If deficiency
occurs, significant amount of minerals absorbed from food in intestines and
less excreted in urine
§
If excess occurs,
less is absorbed and more excreted
§
Note: body has limited
ability to excrete excess minerals
Macrominerals
l
7 macrominerals
l
These are calcium, phosphorus, magnesium,
potassium, sodium, chloride, and sulfur
l
Classified as macro since the RDA is greater
than 100 mg per day or body contains more than 5 grams
Macrominerals
l
Calcium (most abundant mineral in body)
l
DRI varies based
upon age
l
Children 1-3
years 500 mg/day
l
Youth 4-8 years 800
mg/day
l
Adolescents 9-18 years 1,300
mg/day
l
Adults 19-50 years 1,000
mg/day
l
Adults 50 and over 1,200
mg/day
l
Food Sources
l
Dairy products,
fish with small bones (sardines and canned salmon), dark-green leafy
vegetables, calcium-set tofu, legumes, and nuts
l
Certain nutrients
influence calcium absorption, e.g. Vitamin D and lactose enhance Ca++ absorption
l
Other nutrients
slow absorption of Ca++
: legumes & oxalates in spinach; dietary fiber, dietary
phophorus, excess sodium (for every 500 mg increase in urinary sodium
excretion, there is 10 mg increase in Ca++ loss), excess protein;
high intakes of coffee and alcohol
Macrominerals
l
Calcium
(continued)
l
Major Functions
l
Bone metabolism
§
98% is found in
skeleton
§
1% is used for
tooth formation
l
Muscle and other
tissue metabolism
§
1% exists in ionic
state or in combination with certain proteins
§
Muscle contraction
§
Enzyme activation
l
Note:
physiological functions of Ca++ take precedence over formation of
bone tissue; i.e., if body needs Ca++ for certain body functions
like nerve transmission, it will take Ca++ from the bone
Macrominerals
l
Calcium
(continued)
l
Deficiency
l
May develop from
inadequate dietary intake or increased excretion
§
Approximately 40%
of Ca++ intake is absorbed, remainder is excreted in feces
§
It is estimated
that 75% of women do not meet the dietary calcium standards and 50% don’t meet ½ of the AI
§
Exercise may
increase sweat loss of Ca++; the greater the intensity the greater
the potential loss
§
In some athletes,
Ca++ loss matched amount absorbed from daily diet
§
In most cases,
serum Ca++ levels are well-regulated by taking Ca++ from
the bones when needed
Macrominerals
l
Calcium
(continued)
l
Deficiency
l
May result in
result in muscle cramping in athletes
l
May result in
development of colon cancer
l
Possible link to
high blood pressure, however this link is inconclusive
l
Major problem is
bone disease (osteoporosis)
§
Afflicts more than
60% of postmenopausal women, ages 55 to 64 years; higher with older age groups
§
Women are more
susceptible than men
§
Caucasian and
Asian women are more susceptible than African ancestry
§
Estrogen is
critical hormone for normal bone metabolism
Macrominerals
l
Calcium (continued)
l
Supplementation
l
Supplements up to 600 mg/day do not appear to
pose danger
l
Excessive amounts may contribute to abnormal
heart contractions, constipation, and development of kidney stones (check
family history)
l
May be more effective in pre- compared to
post-menopausal women for bone health
§
Also observed to decrease side effects of
premenstrual syndrome (PMS), food craving and water retention
Macrominerals
l
Calcium (continued)
l
Exercise as a “Supplement”
l
ACSM developed a position statement
§
Weight-bearing exercise is essential for normal
bone health
§
Sedentary women may increase bone mass slightly
by becoming more active; key is avoiding bone loss
§
Exercise is not recommended as substitute for
hormone replacement therapy at time of menopause
§
Optimal program for older women should include
activities that improve strength, flexibility, and coordination (important for
balance and reduction of fractures from falling)
Macrominerals
l
Calcium (continued)
l
Osteoporosis in Sport
l
Disturbed calcium metabolism in young, female
athletes (weight-control sports) may result in:
§
Female Athlete Triad
Macrominerals
l
Calcium
(continued)
l
Recommendations
for avoidance of osteoporosis
l
Postmenopausal
women
§
1,000 mg/day if on
estrogen therapy
§
1,200-1,500 mg/day
if not on estrogen therapy
§
Added 400-800
mg/day of Vitamin D may be advisable
l
Follow “age”
recommendations for calcium intake
l
Include
weight-bearing and resistance training activity on a regular basis
l
Dietary intake of
calcium is absorbed best
§
4 glasses of skim
milk provide 1,200 mg calcium
l
Avoid excess
intake of coffee, alcohol, and tobacco
Macrominerals
l
Phosphorus (2nd
most abundant mineral in body)
l
RDA is 700 mg/day
for both men and women
l
Food Sources
include seafood, meat, eggs, milk, cheese, nuts, dried beans & peas, grain
products and vegetables; also soft drinks
l
Calcium:phophorus ratio of 1:1 is appropriate
§
1:4 may be
associated with osteoporosis since larger amounts of phosphorus may impair
calcium metabolism
l
Major Functions
l
80-90% of P in
body helps in development of bones and teeth
l
Help in formation
of cell membranes, DNA, function of B vitamins, and formation of high energy
bonds
l
Helps in 2,3 DPG in RBC’s which facilitate oxygen release to the
muscle
Macrominerals
l
Phosphorus
l
Deficiency is
rare
l
Can result in
bone loss, muscle weakness
l
Supplementation
l
P has been
suggested to improve performance primarily as a buffer to lactic acid formation
§
Marketed as an
ergogenic aid as the main ingredient in PhosFuel
§
Sodium phosphate
supplementation (1 gram, 4 times/day, for 5-6 days) has been shown to improve
performance in highly trained endurance runners; not banned by IOC at present
time
§
Calcium phosphate
supplementation does not seem to give additional benefit to performance
§
Excesses of P are
normally secreted by body although excesses have been associate with GI
disturbances and impaired Ca++ metabolism
Macrominerals
l
Phosphorus
l
Recommendations
l
P supplements are not recommended on a long-term
basis since they may create calcium imbalances, possibly leading to
osteoporosis
l
If using for sport performance, supplementation
should be tested in practice prior to using in competition
Macrominerals
l
Magnesium (4th
most abundant mineral in body)
l
RDA is 400-420
mg/day for men; 310-320 mg/day for women
l
Food Sources
include seafood, nuts, green leafy vegetables, whole grain products, fruits and
vegetables;
l
Major Functions
l
50-60% of Mg in body is stored in skeletal
system
l
It is a component of over 300 enzymes essential
for energy metabolism
l
Helps in 2,3 DPG in
RBC’s which facilitate oxygen release to the muscle
l
May block calcium action in muscle (disruption
of contraction)
Macrominerals
l
Magnesium
l
Deficiency is
rare
l
Can result in
apathy, muscle weakness & twitching, muscle cramps, and cardiac
dysrhythmias; possibly increased blood pressure
l
Long duration
exercise may cause a decrease in blood levels of magnesium
l
Supplementation
l
Mg has been
suggested to improve long distance performance however studies on this mineral
are equivocal
§
Magnesium
supplementation (>350 mg) may cause nausea, vomiting and diarrhea
§
Should be avoided
in individuals with kidney disorders
l
Recommendations
l
Physically active
individuals should get Mg through balanced diet
Trace Minerals
l
Minerals needed in quantities less than 100
mg/day; also known as microminerals
l
Examples
l
Iron (Fe)
l
Copper (Cu)
l
Zinc (Zn)
l
Chromium (Cr)
l
Selenium (Se)
Trace Minerals
l
Iron
l
RDA is 8 mg/day
for men; 18 mg/day women
l
Food Sources
include:
l
Beef, chicken,
fish for heme iron (for RBC’s and myoglobin)
l
Animal and plant
foods (dried fruits, green vegetables, legumes and whole-grain products)
contain nonheme iron
l
Major Functions
l
Formation of
compound in hemoglobin essential to transportation and utilization of oxygen
§
70% of body’s iron
is involved in oxygen metabolism
§
30% is in a
storage form
Trace Minerals
l
Iron
l
Deficiency
l
Most common
nutrient deficiency in the world
§
3-5% of women has
iron-deficiency anemia
§
Symptoms include
paleness, tiredness, low vitality, and impaired ability to regulate temperature
in cold enviroments
l
Supplementation
l
Tends to benefit
athletes with iron deficiency
l
No benefits to
athletes with normal hemoglobin and iron status
l
No significant
benefit to performance of long distance athletes
l
Excess iron can
cause liver damage
l
Recommendation
l
Not recommended to
take extra iron but could be helpful in supplements to female distance runners,
vegetarians, athletes training at altitude, and athletes with restricted
caloric intakes
Trace Minerals
l
Copper
l
RDA is 900 ug for
adults
l
Food Sources
include:
l
Seafood, meats,
nuts, beans, whole-grain products
l
Major Functions
l
Functions as a
metalloenzyme important for iron absorption and oxygen metabolism; a component
of SOD (superoxide dismutase) which is an antioxidant
l
Deficiency is
rare but could lead to anemia
l
Supplementation
can cause nausea and vomiting
l
Recommendation
l
No known benefit
to improving athletic performance
Trace Minerals
l
Zinc
l
RDA is 11 mg/day
for males; 8 mg/day for females
l
Food Sources
include meats, milk, seafood, particularly oysters (1 oyster provides 70%RDA)
l
Major Functions
l
Component of >
100 metalloenzymes involved in energy metabolism (particularly LDH); immune
function; sexual maturation; sensations of taste and smell
l
Deficiency may
result in depressed immune system; impaired wound recovery; decreased appetite;
failure to grow; skin inflammation
l
Supplementation
can cause ↑ LDL & ↓
HDL; nausea & vomiting; impaired copper absorption
l
Recommendation
l
One study has
shown that zinc supplements improved isometric endurance and isokinetic
strength
Trace Minerals
l
Chromium
l
AI is 35 ug/day
for males; 25 ug/day for females
l
Food Sources
include liver, meats, oysters, cheese, whole-grain products, asparagus, and
beer
l
Major Functions
l
Enhances insulin
function for better glucose tolerance
l
Deficiency may
result in glucose intolerance; impaired fat metabolism
l
Supplementation
has been suggested to have beneficial athletic benefits
l
Improve
carbohydrate metabolism during exercise (benefit to endurance athletes?)
l
Enhance anabolic
effect of insulin relative to increasing a.a. uptake
by muscle resulting in increased muscle mass and decreased body fat
l
Most well-designed
studies do not show benefit from chromium picolinate
l
Recommendation
l
Should stay with
dietary levels; excess has been shown to result in chromosomal damage, nerve damage, liver damage, and muscle damage
(amount of intake between 1,200-2,400 from 2 days to 5 months)
Trace Minerals
l
Selenium
l
RDA is 55 ug/day
for adult males and females
l
Food Sources
include liver, meats, fish, chicken, whole-grain products, nuts
l
Major Functions
l
Important for
enzyme functions, particularly those associated with antioxidants
l
Deficiency is
rare but could cause some heart damage
l
Supplementation
l
Excessive amounts
have been associated with nausea, vomiting, abdominal pain, hair loss
l
Shown to be
beneficial in reduction of certain types of cancer
l
Recommendation
l
Not been shown to
improve endurance performance
Trace Minerals
l
Boron
l
RDA is not
established; 1-13 mg/day recommended
l
Food Sources
include dried fruits, nuts, peanut butter, legumes, fresh vegetables,
applesauce, dairy products, grape juice, wine
l
Major Functions
l
Important for cell
membrane structure; steroid and bone metabolism (estrogen); also testosterone
l
Deficiency is rare
but also not known
l
Supplementation
l
Extra amounts are
generally excreted rapidly by kidney; high intakes of 50 mg/day could be toxic
l
Suggested to
improve bone; increase serum testosterone to promote muscle growth during
resistance training
§
Not proven
l
Recommendation
l
Not been shown to
improve performance but boron deprivation from diet could hamper performance
Trace Minerals
l
Vanadium
l
RDA is not
established; 10 ug/day may meet requirements of body
l
Food Sources
include shellfish, grain products, parsley, mushrooms, and black pepper
l
Major Functions
l
Important for
enzyme reactions; particularly its insulin-like effect on glucose and protein
metabolism
l
Deficiency is not
known to occur but if so, may impair glucose metabolism
l
Supplementation
l
Excess may cause
damage to liver and kidney; GI distress (diarrhea)
l
May improve
glucose metabolism in Type II diabetics
l
Suggested to
increase lean body mass and decrease %fat; gain strength
§
Not proven
l
Recommendation
l
Not been shown to
improve performance
Does exercise increase need for Minerals?
l
Many minerals are mobilized during exercise and
lost through sweat, urine, and GI tract (not understood)
l
Generally, if a balanced diet is adhered to by
the athlete, mineral supplementation is not needed.
l
If athlete cannot get adequate diet, one-a-day
vitamin-mineral supplements may be considered
l
Tablet should not contain more than 50-100% RDA
for any mineral