Minerals: Inorganic regulators

1. Minerals: Inorganic regulators Williams, 8th edition Chapter 8

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

3. 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)

4. 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)

5. Calcium • 1.5-2% body weight • 99% in skeleton: 1% in extracellular fluid (nerve transmission, muscle contraction, blood coagulation) •  Positive vs. negative balance: Intake > excretion  + Ca Balance • Intake < excretion  (-) Ca Balance • Intake = excretion  Ca Balance • Intake > excretion  + Ca balance • Should be in + Ca balance during growth

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

7. Effect of exercise on calcium balance: • Calcaneal (Achilles tendon – back of heel) area > 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 > BMD in regular exercising females.

8. 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

9. Main problem with low Ca+ intake  stress fractures Female Athlete Triad Image from http://nsca.hkeducationcenter.com/courses/OEC_Previews/hf-ft303_preview/images/fig_04.gif

10. Ca+ supplementation: • Absorption in > 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.

14. If taking supplements, follow recommendations: Smaller doses (< 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

15. 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

16. “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

17. 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

18. 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

19. 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 

20. Effects of exercise on Mg: • With greater exercise: > urinary Mg loss • Hormones (ADH and aldosterone) that regulate kidney’s handling of Mg, are increased during exercise • Plasma levels  after long distance run (> 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)

21. 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)

22. 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

24. 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

25. Iron, cont. Ø  RDA: women - 15 mg/day; Men: (10 mg/day) Ø  Low Hgb: < 13 mg/dl ØSmall 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

26. 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

27. 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)

28. Dietary factors • Increase iron absorption: • Vitamin C • Heme iron • Hinder iron absorption: • Tea • Coffee • Calcium and phosphorus • Phytates and fiber

29. 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

30. 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

31. 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

32. Zinc sources: • Animal protein • Whole grains • Fortified cereal

33. 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

34. 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 > 100 mg/day: May  LDL-cholesterol and  HDL • Anemia may result •  doses  may impair immune system, cause nausea /vomiting • Supplements not needed

35. 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 > 200 mcg/day  iron deficiency

36. 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

37. 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.

38. 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 (> 200 micrograms/day) may be toxic

39. 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

40. Vanadium (Vanadyl Sulfate) • Insulin-like functions • Inhibits cholesterol; transports glucose into cells • Aided diabetic rats: > glucose tolerance • No effect in humans on improving muscle glycogen synthesis and storage

41. 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

42. 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