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HLTH 213
Minerals Lecture
Minerals
Chapter Outline
I. What's the big deal about minerals?
A. Minerals play important roles throughout the body.
1. They are considered to be essential.
2. Minerals are involved in important catalytic reactions (e.g., iron aids in gluconeogenesis).
3. They serve as key structural components of tissues throughout the body (e.g., calcium provides
structure to bones).
B. Role in sport performance
1. Minerals are crucial for a variety of bodily functions, keeping athletes healthy and training
strong.
2. Certain athlete populations are more prone to mineral deficiencies, warranting a special focus in
the diet.
3. Intake of several minerals, specifically electrolytes, has a great impact on sport performance.
a. Sodium and potassium are the main electrolytes (minerals) lost in sweat.
b. Sodium and potassium must be replaced on a daily basis as well as during endurance
and ultra-endurance sports to optimize performance and prevent medical complications.
II. What are minerals?
A. Characteristics
1. Minerals are inorganic elements or atoms.
2. Minerals contain no calories and, although essential, are needed by the body in very small
amounts (i.e., milligrams or micrograms).
3. After ingestion, mineral structure is not altered.
4. Unlike vitamins, which can be destroyed or altered by exposure to heat, light, alkalinity, or
enzymes, minerals remain unaltered.
B. Two classifications of minerals: major minerals and trace minerals
1. Major minerals
a. Calcium, phosphorus, magnesium, sodium, chloride, potassium, and sulfur are
major minerals.
b. They are required by the body in amounts greater than 100 milligrams per day.
2. Trace minerals
a. Iron, zinc, chromium, fluoride, copper, manganese, iodine, molybdenum, and
selenium are trace minerals.
b. They are required by the body in quantities less than 100 milligrams per day.
3. Both major and trace minerals are stored in the body; when consumed in excess, the levels of
stored minerals can build and become toxic to the body.
4. Toxic levels can be achieved through dietary intake, but toxicity is much more likely to be
caused by high-dosage supplements.
III. What are the major minerals?
A. Calcium
1. RDA/AI for calcium
a. Adequate Intake (AI) for calcium for men and women aged 19 to 50 years is 1,000
milligrams per day.
b. Daily recommendations are higher for men and women aged 9 to 18 as well as those
older than 50 (refer to Table 7.1).
2. Calcium is important for health and sport performance (refer to pages 191–193 for details).
a. Blood clotting
b. Nerve transmission
c. Muscle contraction
d. Disease prevention (hypertension and colon cancer; DASH diet) and weight
management
e. Bone and tooth formation
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5. Foods rich in calcium
a. Dairy products, including milk, yogurt, cottage cheese, and hard cheeses, are
some of the richest sources of calcium.
b. Many soy-based dairy alternatives are fortified with calcium and vitamin D. In most
cases, they provide equivalent amounts of calcium as their dairy counterparts.
c. Green leafy vegetables are a good source of calcium; however, oxalates present in
green vegetables bind to calcium and may prevent its absorption.
d. Calcium-processed tofu is another food that is rich in both calcium and plant-based
proteins.
e. Orange juices, breads, and some cereals are fortified with calcium, and in some cases
provide equivalent amounts to milk.
f. Lactose-intolerant individuals can consume lactose-free products, as well as fortified
soy or rice products, to meet their daily calcium needs.
g. Refer to Figure 7.1.
.
c. Athletes should focus on dietary intake of phosphorus to meet daily needs for health
and performance; supplements are not recommended.
C. Magnesium
1. RDA/AI for magnesium
a. RDA for males aged 19 to 30 is 400 milligrams per day; for men aged 31 to 70 it is 420
milligrams per day.
b. RDA for females aged 19 to 30 is 310 milligrams per day; for women aged 31 to 70
years it is 320 milligrams per day.
2. Functions of magnesium for health and performance
a. It is involved in more than 300 enzyme functions, including DNA and protein
synthesis, as well as blood clotting.
b. It helps to maintain bone strength through its role in bone metabolism.
c. It aids in the regulation of blood pressure; magnesium has an inverse relationship with
blood pressure, adequate daily intake protects against hypertension.
d. It stabilizes the structure of ATP and improves the effectiveness with which the
enzyme adenosine triphosphatase acts on ATP.
e. It is involved in glucose and lipid metabolism.
f. Inside the mitochondria, magnesium is essential for the aerobic production of ATP via
the electron transport chain.
g. During activity, muscles rely on magnesium for proper contraction and relaxation.
3. Complications of magnesium deficiency
a. Deficiency causes a variety of problems, such as altered cardiovascular function,
including hypertension, as well as impaired carbohydrate metabolism.
b. Symptoms of deficiency include loss of appetite, muscle weakness, and nausea (first
signs of deficiency usually do not surface for several months because a significant
amount of magnesium is stored in the bones).
c. If an athlete continues to consume a diet chronically low in magnesium, other
symptoms will emerge, such as muscle cramps, irritability, heart arrhythmias, confusion,
and possibly high blood pressure.
d. If the deficiency is left untreated, death can result.
e. Insufficient magnesium intake allows calcium's contracting effect to dominate over
magnesium's relaxing effect, and higher blood pressure will ensue.
f. It has been suggested that prolonged or intense exercise may decrease magnesium
levels due to increased excretion in sweat and urine, as well as increased usage by the
cells for energy production.
g. Some researchers have found that the decrease in serum magnesium levels during
long-duration exercise contributes to cramping (resulting in sports supplements targeted
for the prevention of muscle cramps).
h. Overall, few studies have shown a direct link between magnesium deficiency and
cramping or impaired performance.
D. Sodium
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1. RDA/AI for sodium
a. To function properly, the body requires only approximately 500 milligrams of sodium
per day.
b. The RDA for sodium is 1,500 milligrams per day.
2. Functions of sodium for health and performance
a. It maintains blood pressure; high intake is linked to hypertension.
b. It is required for the transmission of nerve impulses.
c. It is required for muscle contraction.
d. It aids in the absorption of glucose, which makes it a key component of sports
beverages designed to provide energy during exercise.
5. Foods rich in sodium
a. Table salt (1 teaspoon = approximately 2,300 milligrams of sodium), soy sauce,
condiments, canned foods, processed foods, fast foods, smoked meats, salted snack
foods, and soups are all rich sources of sodium.
b. Most Americans consume well above the upper limit of 2,300 milligrams per day;
some people take in 8,000 to 11,000 milligrams per day!
c. Refer to Figure 7.4.
6. Suggestion for a sodium-rich meal or snack
a. Lunch: Grilled cheese sandwich with 1 cup tomato soup
b. Total sodium content = 1,391 milligrams
7. Sodium supplements
a. In general, sodium supplements are not required; dietary sources of sodium are
adequate.
b. In activities lasting longer than 4 hours, sodium supplements may be indicated (refer to
Chapter 8).
E. Chloride
1. The AI for chloride for both men and women is 2,300 mg per day.
2. Functions of chloride for health and performance
a. It acts as a "disinfectant" to maintain health inside the body.
b. It combines with hydrogen to form hydrochloric acid. In the stomach, hydrochloric
acid helps to kill harmful bacteria.
c. White blood cells also use chloride to kill invading bacteria throughout the body.
d. In neurons, the movement of chloride, as well as calcium, sodium, and potassium,
allows for the transmission of nerve impulses throughout the body.
e. It is one of the extracellular electrolytes required to maintain fluid balance throughout
the body.
5. Foods rich in chloride
a. Salt, or sodium chloride (NaCl), is the richest source of chloride in the American diet.
b. It is found in small amounts in fruits and vegetables.
c. Refer to Figure 7.4.
6. Suggestion for a chloride-rich meal or snack
a. Dinner: Meatball sandwich and a small bag of pretzels
b. Total chloride content = 3,092 milligrams
7. Chloride supplements do not appear to enhance physical performance, and therefore are not
recommended.
F. Potassium
1. The RDA for potassium is 4,700 milligrams per day for men and women.
2. Functions of potassium for health and performance
a. It counteracts the effects of sodium on blood pressure; thus, it helps maintain low
blood pressure.
b. Interchange and flow of potassium and sodium in and out of cells is responsible for the
transmission of nerve impulses and muscle contractions.
c. One of the intracellular electrolytes critical for fluid balance in the body, especially
during exercise.
3. Complications of potassium deficiency
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a. Hypokalemia, or low blood potassium, is caused by frequent vomiting, diarrhea, and
use of diuretics, as well as low potassium intake.
b. Athletes with high sweat losses are also at risk for potassium deficiency, which may
result in muscle cramps.
c. Common symptoms of potassium deficiency include muscle weakness and loss of
appetite.
d. A rapid change in potassium status or long-term low potassium levels can lead to heart
5. Foods rich in potassium
a. Fruits and vegetables are the richest sources of potassium.
b. Meat, milk, coffee, and tea are also significant sources.
c. Food processing tends to remove potassium and add sodium, thereby contributing to
the imbalanced intake of these two minerals.
d. Refer to Figure 7.5.
6. Suggestion for a potassium-rich meal or snack
a. Refer to Summertime Salad recipe on page 201
G. Sulfur
1. No RDA, EAR, or AI for sulfur because of the fact that it can be obtained from food and water,
as well as be derived from specific amino acids in the body.
2. Functions of sulfur for health and performance
a. Sulfur is a component of hundreds of compounds in the body.
5. Foods rich in sulfur
a. Highest concentrations are found in some fruits, soy flour, certain breads, and
sausages.
b. Juices, beers, wines, and ciders also contain a significant quantity of sulfur.
c. Drinking water is another common source of sulfur; however, quantities can vary
dramatically based on the region of the country and water source.
6. Suggestion for a sulfur-rich meal or snack
a. Because no RDA/AI level has been set for sulfur, a "sulfur-rich" meal cannot be
recommended.
b. Athletes should include sulfur-containing foods on a daily basis in addition to
IV. What are the trace minerals?
A. Iron
1. RDA/AI for iron
a. RDA for men aged 19 to 50 years and postmenopausal women is 8 milligrams per day.
b. RDA for females aged 19 to 50 is 18 milligrams per day.
2. Functions of iron for health and performance
a. It aids in the formation of compounds essential for transporting and utilizing oxygen.
b. Heme is the iron-containing portion of both hemoglobin and myoglobin.
c. Hemoglobin is a protein–iron compound in red blood cells that carries oxygen from the
lungs to the cells and tissues of the body.
d. Myoglobin is found in muscle and facilitates the transport of oxygen to the muscle
cells.
e. It plays a role in healthy immune function and brain development as well as energy
production through its inclusion in various enzymes.
3. Complications of iron deficiency
a. Iron deficiency is one of the most common nutrient deficiencies worldwide.
b. Iron is lost through skin, hair, sweat, and the intestinal tract.
c. Women lose significantly more iron than men due to monthly iron losses through
menstruation.
d. Iron deficiency occurs mainly as a result of poor intake relative to daily needs.
e. Iron deficiency occurs in three stages: iron depletion, iron-deficiency erythropoiesis,
and iron-deficiency anemia. Refer to page 203 for details.
4. Why are athletes at risk for iron-deficiency anemia?
a. Athletes, especially female athletes, distance runners, and vegetarian athletes, are at a
greater risk than the general population for iron-deficiency anemia.
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b. Athletes may be at an increased risk for iron deficiency because of low dietary intake;
the type of food consumed; increased demand for myoglobin, hemoglobin, and energyproducing enzymes; the type of sport; and loss through sweat (refer to page 204 for
details).
c. Sports anemia is a unique condition and not a true anemia. Short-term sports anemia
can occur in individuals beginning an exercise program or initiating a period of intense
training. (Training increases blood volume, thus diluting blood concentration. A test
would then reveal low hemoglobin levels). Long-term sports anemia has been found in
highly trained endurance athletes (red blood cells become very efficient at carrying and
releasing oxygen to the tissues, therefore not as many are required in the blood).
d. To prevent iron-deficiency anemia in athletes, the annual development of standard
protocols for assessment and treatment of iron deficiency is recommended (refer to
6. Foods rich in iron
a. There are two types of iron: heme and nonheme.
b. Heme iron is found only in animal products, such as beef, poultry, and fish. It boasts a
greater bioavailability than nonheme iron.
c. Nonheme iron is primarily found in plant foods, such as soy products, dried fruits,
legumes, whole grains, fortified cereals, and green leafy vegetables.
d. The bioavailability of nonheme iron can be enhanced when sources are consumed with
either a meat product or a vitamin C source.
e. Absorption can be inhibited by calcium, tannins in tea, phytic acid in grains, or
excessive fiber. Therefore, foods rich in these nutrients should be present in small
amounts when consuming a good source of iron.
f. Refer to Figure 7.7.
7. Suggestion for an iron-rich meal or snack
a. Dinner: 2 cups of meat-and-bean chili, a whole wheat dinner roll, and 2 cups of
spinach salad.
b. Total iron content = 11.3 milligrams
8. Iron supplements
a. If an athlete is diagnosed with iron-deficiency anemia, iron supplements are typically
indicated. Normalizing iron status will improve performance and endurance.
b. For athletes with normal iron intake and blood levels, iron supplementation will
probably not enhance performance, and may actually cause harm.
c. Individual iron supplements should be taken only under the care of a physician.
B. Zinc
1. The RDA for zinc is 11 milligrams per day for men and 8 milligrams per day for women.
2. Functions of zinc for health and performance
a. It is associated with more than 200 enzymatic systems.
b. It plays a role in wound healing, thus enhancing immune function.
c. It aids in the synthesis of RNA and DNA, thus influencing gene expression.
d. It is involved in the growth and maintenance of various tissues.
e. It is required for the synthesis of hormones.
f. It is required for the synthesis of proteins.
4. Symptoms of zinc toxicity
a. The upper limit for zinc is 40 milligrams per day.
b. High doses in supplement form can impair iron and copper absorption, which over
time may contribute to anemia.
c. Zinc doses of approximately 100 mg per day or greater can increase LDL and decrease
high-density lipoprotein (HDL), leading to increased risk for heart disease.
d. More immediate and recognizable signs and symptoms of zinc overload are nausea and
vomiting.
5. Foods rich in zinc
a. Animal products, especially beef and other dark meats; fish, particularly oysters; eggs;
and dairy products, are rich in zinc.
b. Plant sources include whole grains, wheat germ, and legumes.
c. Refer to Figure 7.8.
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6. Suggestion for a zinc-rich meal or snack
a. Thanksgiving leftovers: A sandwich with 3 oz dark meat turkey and 1 slice of Swiss
cheese with 1/2 cup cranberry sauce and an 8-oz glass of skim milk
b. Total zinc content = 7.3 milligrams
7. Zinc supplements
a. In general, zinc supplements are not essential.
b. For individuals who are deficient, a short-term supplement plan may provide health
and performance benefits.
c. For those with adequate zinc intake and stores, supplementation may have no effect.
d. Research on the effects of zinc supplementation on athletic performance is limited and
equivocal.
e. Large doses of zinc in supplement form should be avoided because of possible toxicity
and mineral–mineral interactions.
C. Chromium
1. AI for chromium is 35 micrograms per day for men and 25 micrograms per day for women.
Recommendations are lower for older athletes.
2. Functions of chromium for health and performance
a. The major function of chromium appears to be its ability to enhance the action of
insulin; the mechanism is still under investigation (possible interaction with glucose
tolerance factor).
b. Chromium may increase the number of insulin receptors, thus increasing insulin
sensitivity and improving type 2 diabetes.
c. Chromium may also affect blood lipid levels and proper immune function.
5. Foods rich in chromium
a. It is found in a unique mix of foods including mushrooms, prunes, nuts, whole grains,
brewer's yeast, broccoli, wine, cheese, egg yolks, asparagus, dark chocolate, and some
beers.
b. The chromium content in foods is highly variable; therefore, current databases lack
thorough information on the quantity of chromium in various dietary sources.
6. Suggestion for a chromium-rich meal or snack
a. Dinner: Homemade pasta primavera made with 2 cups of whole wheat pasta and 1/2
cup each of mushrooms, broccoli, and asparagus in a light tomato sauce sprinkled with 1
T parmesan cheese
b. Total chromium content = ~35 micrograms
7. Chromium supplements
a. Small quantities of chromium have been found to be lost in sweat and urine with
strenuous exercise. However, for athletes consuming adequate total calories and
chromium-rich foods, supplementation is not warranted.
b. Athletes who follow a low-calorie diet for an extended period of time should be
monitored for adequate daily chromium intakes.
c. Chromium supplements are often marketed to athletes and touted as fat burners and
muscle builders. Research has not confirmed these claims.
d. Athletes should avoid ingesting too much chromium through supplements. Excessive
intake can interfere with iron and zinc absorption, creating deficiency problems.
e. Some research warns that excessive chromium intake over time may cause
chromosomal damage, leading to a plethora of health and performance issues.
D. Fluoride
1. The AI for adults is 4 milligrams a day for men and 3 milligrams a day for women.
2. Functions of fluoride for health and performance
a. It is critical for the mineralization of bones and teeth.
b. It has also been suggested that fluoride may help strengthen the resistance of
interosseous ligaments or muscle tendons during dislocations and sprains, and prevent
tendonitis in athletes.
3. Complications of fluoride deficiency
a. Deficiency may increase dental caries and compromise the integrity of the bone.
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b. Poor dentures can lead to a variety of problems in the mouth, which can potentially
alter eating patterns or types of foods consumed.
c. Compromised bone integrity can lead to fractures, bone pain, and ultimately decreased
performance.
5. Foods rich in fluoride
a. Water is the main source of dietary fluoride in the United States. Water contains
approximately 0.7 to 2 milligrams of fluoride per liter.
b. Community water suppliers often fluoridate their water to increase the concentration of
fluoride in drinking water. However, not all communities supply fluoridated water. In
addition, well water varies greatly in fluoride content.
c. Fluoride content is often low in bottled waters.
d. Teas, seafood, and foods that are prepared with water contain appreciable fluoride (see
6. Suggestion for a fluoride-rich meal or snack
a. Snack: 16 oz of hot black tea with a teaspoon of honey
b. Fluoride content = 1.6 milligrams
7. Fluoride supplements
a. Fluoride supplements are generally not recommended.
b. Short-term use of fluoride supplements under medical supervision may be appropriate
for bone strengthening for those who have consistently low fluoride intake.
c. Fluoride supplements are inappropriate for long-term use because of toxic effects and
the lack of research data on the safety of long-term use.
E. Copper
1. The RDA for copper for men and women is 900 micrograms per day.
2. Functions of copper for health and performance
a. Copper is a component of the enzyme ceruloplasmin, which is involved in iron
metabolism.
b. It is an integral part of a variety of antioxidant enzymes, including superoxide
dismutase.
c. Lysyl oxidase, another copper-dependent enzyme, is needed for the cross-linking of
elastin and collagen, which strengthens connective tissues.
d. Copper also participates in the electron transport chain (cytochrome oxidase).
3. Complications of copper deficiency
a. Deficiency is rare in the United States.
b. High doses of iron and zinc can interfere with copper absorption and therefore
contribute to copper deficiency problems.
c. Signs and symptoms of copper deficiency are anemia, decreased white blood cell
counts, and bone abnormalities.
d. Menkes syndrome is a rare genetic disorder that involves a failure to absorb copper.
Copper accumulates in the intestinal wall and other organs, leading to neurological
degeneration, abnormal connective tissue development, and low bone mass.
4. Symptoms of copper toxicity
a. The upper limit for copper intake is 10,000 micrograms per day.
b. The results of copper overload are gastrointestinal distress and liver damage.
c. Wilson's disease is a genetic disorder characterized by an excessive accumulation of
copper, which ultimately leads to anemia, as well as liver and neurological problems.
5. Foods rich in copper
a. Organ meats, seafood, nuts, seeds, wheat bran, cereals, whole grains, and cocoa
products are good sources of copper.
b. Refer to Figure 7.11.
6. Suggestion for a copper-rich meal or snack
a. Lunch: 1 1/2 cups clam chowder, 15 wheat crackers, and 1 cup of fruit salad sprinkled
with 1 T sunflower seeds
b. Total copper content: 610 micrograms
7. Copper supplements
a. Because most athletes generally consume adequate levels of copper, supplements are
not needed nor recommended.
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b. Additionally, high doses of copper can become toxic, leading to side effects such as
nausea and vomiting.
F. Manganese
1. AI for manganese is 2.3 milligrams per day for men and 1.8 milligrams per day for women.
2. Functions of manganese for health and performance
a. Manganese activates a variety of health-related enzymes that are involved in skeletal
growth, protein and hemoglobin synthesis, lipid and carbohydrate metabolism, and
antioxidant functioning.
b. Glutathione peroxidase and other antioxidant enzymes that are dependent on
manganese, such as superoxide dismutase, catalase, and glutathione reductase, function to
reduce lipid peroxidation.
c. Manganese is also involved in energy metabolism and fat synthesis.
5. Foods rich in manganese
a. Whole grains, legumes, green leafy vegetables, tea, and fruit are all good sources of
manganese.
b. Refer to Figure 7.12.
6. Suggestion for a manganese-rich meal or snack
a. Refer to the Sweet Potato Fries recipe on page 211
b. Total manganese content = 0.85 milligrams
7. Manganese supplements are neither needed nor recommended for athletes.
G. Iodine
1. RDA for iodine is 150 micrograms per day for both men and women.
2. Functions of iodine for health and performance
a. Iodine is required for synthesis of hormones secreted by the thyroid gland, namely
tetraiodothyronine (thyroxine or T4) and triiodothyronine (T3).
b. Iodine is related to athletic performance through the action of the thyroid hormones,
which play a role in protein synthesis in skeletal muscle, energy expenditure, weight
control, and body temperature regulation.
3. Complications of iodine deficiency
a. A lack of dietary iodine can lead to the development of goiter, the enlargement of the
thyroid gland.
b. Symptoms of iodine deficiency are similar to those for hypothyroidism and include
cold intolerance, weight gain, and decreased body temperature.
the development of goiter.
5. Foods rich in iodine
a. Beginning in 1924, iodine was added to salt to increase Americans' intake of this
mineral in order to prevent goiter and other related issues.
b. Iodine can also be found in seafood, dairy products, grains, and cereals.
c. Refer to Figure 7.13.
6. Suggestion for an iodine-rich meal or snack
a. Lunch: A turkey sandwich on whole wheat bread with lettuce and tomato and 1 cup of
skim milk
b. Total iodine content = 105 micrograms
7. Iodine supplements are neither needed nor beneficial for athletes.
I. Selenium
1. RDA for selenium is 55 micrograms per day for both men and women.
2. Functions of selenium for health and performance
a. It is a component of many body proteins, the selenoproteins being the most notable.
b. Selenocysteine is the selenium form associated with glutathione peroxidase, an
antioxidant enzyme that helps to combat free-radical damage to cells.
c. Selenium and vitamin E work synergistically to quench more free radicals than either
nutrient could on its own.
d. For the effects of selenium on exercise-induced free radical formation, refer to the
section "What vitamins or compounds have antioxidant properties?" in Chapter 6.
e. Selenium-associated enzymes have also been linked to proper thyroid and immune
function, as well as to healthy fetal development.
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5. Foods rich in selenium
a. Mainly found in animal products, with seafood ranking near the top of the list.
b. Plant foods contain selenium; however, content may vary dramatically based on the
selenium concentration of the soil where the plants were grown.
c. Refer to Figure 7.14.
6. Suggestion for a selenium-rich meal or snack
a. Dinner: Shrimp stir-fry with 3 oz of shrimp, 1 cup of mixed vegetables, and 1 cup of
cooked brown rice
b. Total selenium content = 45 micrograms
7. Selenium supplements
a. Research on the ergogenic benefits of selenium supplements is still in its infancy.
b. Some research has shown that the antioxidant status of athletes participating in intense
training diminishes, leading some to propose that selenium and other antioxidant
supplements may be warranted.
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