Minerals: Inorganic regulators

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Minerals Inorganic regulators

• Williams, 8th edition
• Chapter 8

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Minerals

• RDA for minerals See p. 281, table 8.1
• Major gt 5 grams stored in body
• Trace lt 5 g stored
• Major Calcium, Chloride, Magnesium, Phosphorus,
  Potassium, Sodium, and Sulfur.
• Trace Boron, Chromium, Cobalt, Copper, Fluoride,
  Iodine, Iron, Manganese, Selenium, and Zinc.

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Basics

• Minerals are inorganic elements
• Main functions
• Building blocks for bones, teeth, muscles, and
  other body tissues
• Some are components of metalloenzymes involved
  in regulation of metabolism
• Some are ions or electrolytes (particles carrying
  electric charges)

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• Read Table 8.2 on p. 283 for complete list of
• All major mineral names
• Food sources
• Major functions in body
• Deficiency symptoms
• Toxicity symptoms (from excessive consumption)

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Calcium

• 1.5-2 body weight
• 99 in skeleton 1 in extracellular fluid
  (nerve transmission, muscle contraction, blood
  coagulation)
•  Positive vs. negative balance Intake gt
  excretion ? Ca Balance
• Intake lt excretion ? (-) Ca Balance
• Intake excretion ? Ca Balance
• Intake gt excretion ? Ca balance
• Should be in Ca balance during growth

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Calcium balance

• Blood level constant
• Ca intake and activity affect bone density
• Bone mineral content (BMC) and bone mineral
  density (BMD) is gt in pre- menopausal women who
  consume gt 500 mg/day.
• Also gt in those with physical activity gt 45
  min./day 4-7 days/week
• In women who exercise regularly BMD gt in radial
  (thumb side of forearm) area
• Ca fortified foods often have 100 RDA/serving

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Effect of exercise on calcium balance

• Calcaneal (Achilles tendon back of heel) area gt
  in women who were very active as children
• Lumbar (region of back and side between hips and
  pelvis), and femoral (thigh bone) areas also had
  gt BMD in regular exercising females.

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Osteoporosis and sports

• Female athlete triad (see next slide)
• Secondary amenorrhea cessation of menses for
  extended time
• Athletic amenorrhea same but observed in
  athletic females, may be more intermittent
• Low serum calcium levels may impair neuromuscular
  functions

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Female Athlete Triad
Main problem with low Ca intake ? stress
fractures

• Image from http//nsca.hkeducationcenter.com/cours
  es/OEC_Previews/hf-ft303_preview/images/fig_04.gif
  

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Ca supplementation

• Absorption in gt in early puberty (age 10-11)
• Calcium citrate ? ? iron absorption
• Ca carbonate requires gastric acid for
  absorption (may ? absorption of non- heme Fe in
  food)
• Post menopausal? If no ERT, then supplementation
  of 1500 mg/day ? ? rate of bone loss.

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If taking supplements, follow recommendations

• Smaller doses (lt 500) mg between meals for better
  absorption (Except Ca C03 which requires
  gastric acid for absorption) 
• See Calcium balance in adults figure 8.1 on p.
  284
• See Table 8.3, p. 286 Osteoporosis risks

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Phosphorus

• Mostly stored in bone
• Structural function in bones/teeth
• Part of nucleic acids
• Needed for E metabolism (part of high energy
  complex, ATP)
• Part of phospholipids (structure to cell
  membrane)
• Assists in DNA formation

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Phosphate loading

• Note Phosphorus is present in all animal tissues
  ? deficiency rare
• Not recommended as a supplement (may ? Ca
  absorption)
• Supplements may ? V02 max and ? blood lactate
• Phosphate loading controversial

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Phosphorous supplements, cont.

• Elevated inorganic phosphate in cells activates
  glycolysis ? increases glycolytic metabolite
  DPG ? believed to facilitate 02 delivery to
  working muscles
• May also ?creatine phosphate
• Studies inconclusive

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Magnesium

• Co-factor in enzymes used in CHO metabolism.
• Part of ATPase involved in muscle contraction
  and all functions involving ATP
• Helps make glutathione (natural antioxidant)
• Co-factor in ATP dependent reactions
• Blood levels ? during exercise (i.e. more
  released from tissue) aids physiological
  reactions

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Magnesium, cont.

• Deficiency would compromise endurance
• Symptoms of deficiency apathy, weakness, muscle
  twitching, cramps
• High doses have laxative effect
• Sources Milk, yogurt, whole grains, green leafy
  vegetables, beans, nuts 

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Effects of exercise on Mg

• With greater exercise gt urinary Mg loss
• Hormones (ADH and aldosterone) that regulate
  kidneys handling of Mg, are increased during
  exercise
• Plasma levels ? after long distance run (gt 2
  hours) RBC take up Mg from ECF
• Mg needed by muscles to assist in metabolic
  processes.
• ?intensity resistance exercise ? ? blood Mg, (but
  believed to be related to changes in plasma
  volume associated with this type of exercise)

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• Read Table 8.4 on p. 295 for complete list of
• All trace mineral names
• Food sources
• Major functions in body
• Deficiency symptoms
• Toxicity symptoms (from excessive consumption)

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Iron

• See figure 8.4 on p. 296
• Primary role in hemoglobin synthesis
• Transports 02 from lungs ? body tissues
• Aids myoglobin synthesis
• Stored in bone marrow, liver, spleen
• Essential for electron transfer

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Causes of low iron status in athletes

• ? plasma volume
• ? iron excretion
• ? GI bleeding in long distance runners
• Distance runners develop hematuria (Hgb/Mgb in
  urine)
• Repeated foot contact with ground ? RBC hemolysis

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Iron, cont.

• Ø  RDA women - 15 mg/day Men (10 mg/day)
• Ø  Low Hgb lt 13 mg/dl
• Ø  Small amount Fe is lost in sweat
• Ø  Supplements beneficial in replacing iron
  stores but too much is toxic
• Ø NOTE excess iron ? accumulates in liver as
  hemosiderin ? excess can cause
  hemochromatosis if genetically predisposed ?
  very damaging to liver
• Ø  Also, iron is a pro-oxidant ? may oxidize
  LDL leading to plaque in arteries

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Sports anemia

• Not a true anemia
• Appears to develop in early stages of training
• Increased plasma volume ? dilution of RBC and
  lower Hgb concentration
• Adequate dietary iron is essential
• Supplements not usually needed

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Iron recommendations and sources

• Contained in hemoglobin and myoglobin or occurs
  as part of enzymes in the energy-yielding
  pathways
• Lost through menstruation and other bleeding the
  shedding of intestinal cells protects against
  overload. Too much iron is toxic.
• Heme iron (bound to hgb) has ? bioavailability
  than non-heme (plant courses)

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Dietary factors

• Increase iron absorption
• Vitamin C
• Heme iron
• Hinder iron absorption
• Tea
• Coffee
• Calcium and phosphorus
• Phytates and fiber

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Copper

• Catalyst for iron absorption and mobilization
• Assists in collagen formation and norepinephrine
  formation
• Supeoxide dismutase (SOD), a natural antioxidant
  produced in body, contains copper.
• Plasma concentration of copper ?during acute
  exercise.
• No RDA for copper (Found in liver, seafood, nuts,
  and legumes)
• Supplements not recommended

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Zinc

• Has role in metabolic functions
• Assists enzymes in all cells.
• Involved in immune function and support of WBC in
  immune system
• Toxic in large amounts
• Animal foods are best sources. 
• Supplements not recommended

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Zinc works with enzymes that

• Make parts of cells' genetic material
• Make heme in hemoglobin help pancreas with
  digestive functions helps metabolize CHO,
  protein, fat
• Liberate vitamin A from liver storage  

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Zinc sources

• Animal protein
• Whole grains
• Fortified cereal

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Zinc deficiency

• ? Immunity
• Growth retardation
• Poor appetite
• Note athletes who over-restrict calories (e.g.
  gymnasts and wrestlers) are most at risk for Zn
  deficiency

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Zinc supplementation and performance

• One study ? isometric endurance and isokinetic
  strength during fast contractions
• Additional research is needed
• Megadoses (25-50 mg/day) may impair absorption
  of copper and iron
• Supplements gt 100 mg/day May ? LDL-cholesterol
  and ? HDL
• Anemia may result
• ? doses ? may impair immune system,
• cause nausea /vomiting
• Supplements not needed

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Chromium

• Works with insulin to control blood glucose
• Potentiates effects of insulin in CHO, lipid, and
  protein metabolism
• Forms complex with nicotinic acid and
  glutathione, forming organic compound known as
  Glucose tolerance factor (GTF)
• Caution prolonged supplementation of gt 200
  mcg/day ? iron deficiency

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Chromium cont.

• Promoted as alternative to anabolic steroids ?
  claimed to increase lean mass
• Research reports conflict
• No hard evidence that it increases lean mass
• Megadoses toxic to liver

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Research conclusions chromium

• Little to no effect on strength, body composition
  and exercise endurance in adults
• Study (Lukaski, 2004) chromium had no effect on
  body fat or lean mass
• Glucose effectiveness chromium improved insulin
  sensitivity in obese subjects with family history
  of Type II diabetes.

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Selenium

• Works with vitamin E to protect body compounds
  from oxidation
• Deficiency heart disease
• Mainly found in protein rich foods
• Strenuous exercise can ? free-radical production
• May prevent lipid peroxidation
• Supplements (100 mcg/day) may prevent heart
  disease
• Excessive doses (gt 200 micrograms/day) may be
  toxic

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Boron

• Influences calcium and magnesium metabolism
• Alleged benefit ? testosterone, growth and
  strength
• Research postmenopausal women deprived of
  boron, then given supplements for 48 days ?
  doubled serum testosterone.
• Subsequent research no ? in testosterone, lean
  mass, or strength in body builders
• Found in dried fruit, nuts, peanut butter,
  grapes, apples, and dairy products

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Vanadium (Vanadyl Sulfate)

• Insulin-like functions
• Inhibits cholesterol transports glucose into
  cells
• Aided diabetic rats gt glucose tolerance
• No effect in humans on improving muscle glycogen
  synthesis and storage

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Vanadyl sulfate as ergogenic aid

• No data support its role as an anabolic
  supplement in humans
• Studies no significant changes in body
  composition, or weight training.
• Has corrective effect on diabetes-induced rats -
  normalized glucose concentrations and insulin
  levels

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Does exercise increase overall need for minerals?

• Exercise may ? mineral loss by
• Mobilization into circulation
• Removal by kidneys
• Sweat loss
• Some shedding from GI tract
• Dietary adequacy essential one-a-day type of
  supplement with 100 of RDA may be good
  insurance, megadoses are harmful