Chapter 9: Water and the Major Minerals

1. Chapter 9: Water and the Major Minerals

2. Water: Essential Nutrient • Death occurs • Without food • Without vitamins, minerals • Without water

3. Water • Comprises 50-70% of the body • Muscle contains 73% water (fat contains ~20%) • Intracellular fluid • Fluid within the cell (2/3 of total) • Extracellular fluid • Outside the cells (1/3 of total)

4. Water Content Varies By Tissue • Lean muscle • Fat • Bones

5. Water Content Varies: By Age • Newborn • Adult • Elderly

6. Water Content Varies Daily • Salt intake • Hormonal • 2 cups fluid = 1 pound • Kidneys excrete excess

7. Functions of Water • Almost universal solvent • Dissolves • Nutrients • Wastes • Urea • Carbon dioxide

8. Functions of Water • Removal of body waste • Via urine • Excrete 1-2 quarts/day • Urea excretion • Sodium excretion • Avoid concentrated urine • 21/2 cups --- dark yellow • Can promote kidney stones

9. Functions of Water • Body temperature regulation • Metabolism generates heat • Buildup is dangerous • Water absorbs any excess heat • Body secretes fluid via perspiration • Skin is cool as perspiration evaporates

10. Functions of Water • Lubricant • Joints • Synovial fluid • Shock absorber • Amniotic fluid • Cerebrospinal fluid

11. Are You Drinking Enough? • Recommend 1ml per 1kcal • ½ oz / pound body weight

12. Daily Water Losses • Urine – largest loss • Skin –ongoing evaporation • Lungs – vapor • Feces

13. Sources of Water • Fluids • Water • Other beverages • Food • Fruits and vegetables • Meat • All but dried foods • Metabolism • Energy nutrients → carbon dioxide, energy, water

14. The Thirst Mechanism • Not reliable • Concerns for infants, older adults, athletes • Athletes need to monitor their fluid status • Weigh themselves before and after training • Goal is to consume 3 cups for every pound lost • Illness (vomiting, diarrhea, fever)

15. Ignoring Thirst • Shortage of water in the body • Increase fluid conservation • Antidiuretic hormone • From the pituitary glad • Forces the kidney to conserve water (reduce urine flow) • Aldosterone • Responds to the drop in blood pressure • Signals the kidney to retain sodium (water)

16. Thirst • Signal is not triggered until person loses 1%-2% of body weight in fluid • Lost of 4% causes muscle to lose significant strength and endurance • Lost of 10%-12% causes heat intolerance • Lost of 20% results in coma and death • Dark yellow urine is a sign of inadequate fluids

17. Water Safety • Most municipal tap water is safe • The Environmental Protection Agency and local municipalities look for contaminants • Power to local and state authorities to advise public

18. Water Safety • Chlorine and ammonia are added to kill most microbes • Small cancer risk (2/1 million people) • Chlorine can be evaporated via boiling or standing • Much higher risk in using untreated water

19. Water Safety • Rural areas may need to have their water tested due to well contamination due to agricultural runoff • Estimated that 10 million Americans may drink water that doesn’t meet EPA guidelines • Cryptosporidium, a parasite, sickened 400,000 people in Milwaukee; not killed by chlorine • High risk people are advised to boil their drinking water for one minute prior to use for drinking (HIV-AIDS, chemotherapy patients)

20. Alternatives to Chlorinated Tap Water • Boil • Store overnight • Filters • Activated carbon • Reverse osmosis • Distillation • UV sterilization • Ozone

21. Bottled Water • Expensive • Environmental impact • Manufacture • Transport • Landfill

22. Bottled Water Sources • 75% springs/wells • Ozone • 25% municipal tap water • Carbon filtered

23. Bottled Water • Independent testing • 1/3 was contaminated • Bacteria • Arsenic • Organic elements • Check label • Source • Treatment • State-interstate FDA regulated

24. Water Safety • Let cold water run for a minute or two before drinking or using in cooking; will reduce risk of lead exposure • Don’t use hot water for food preparation

25. Water and Minerals • Related 3 ways • Hard/soft water • Fluid balance • Acid base balance

26. Fluid Balance • Water shifts freely in and out of the cells • Controlled by the electrolyte concentration • “Where ions go, water is sure to follow” • Intracellular water volume depends on intracellular potassium and phosphate concentrations • Extracellular water volume depends on extracellular sodium and potassium concentrations

27. Na+, K+, Cl- • Attract water • Dissolve in water • Electrical charge = electrolytes

28. Cell Membranes • Water permeable • Impermeable to minerals

29. Osmosis • The passage of a solvent such as water through a semi-permeable membrane from a less concentrated compartment to a more concentrated compartment

30. Osmosis • Water moves across membrane • Low concentration to high • Equalizes solute concentration • Minerals do not move • Draw water across membrane

31. Acid-Base Balance • Blood pH 7.35-7.45 • Death • pH 8.0 alkalosis • pH 6.8 acidosis • Buffers • Protein • Electrolytes • Gather/release hydrogen ions

32. Minerals: Definition • Inorganic (contain no carbon) • Separate elements • Required in small amounts

33. Cofactors Bone and connective tissue Blood Metabolism Growth & reproduction Function/formation nerves & muscles Cell membrane transport Minerals function together: Bone formation Electrolytes Blood Functions of Minerals

34. Minerals in the Body

35. Mineral Classification • Major minerals • Require >100 mg /day (1/50 of a teaspoon) • Calcium, phosphorus • Trace minerals • Require < 100 mg/day • Iron, zinc

36. Bioavailability of Minerals • Not all ingested minerals can be absorbed • Example: only 5% of the calcium in spinach is absorbed because spinach contains oxalic acid • About 25% of dietary iron is absorbed (better absorbed from dairy products)

37. Bioavailability of Minerals • Presence of binders and dietary fiber • Minerals in animal products are better absorbed • The more refined a food is, the fewer minerals • Only iron is added back to enriched grain products

38. Fiber-Mineral Interactions • Phytic acid (phytate) in grain fibers can limit absorption of some minerals by binding to them • Oxalic acid: substance in plants (spinach) that binds minerals • High fiber diets can decrease the absorption of iron, zinc, magnesium, and other minerals

39. Bioavailability of Minerals • Mineral content of plant foods reflects the soil in which is it grown • Mineral/mineral competition: too much of one mineral can interfere with the absorption of another • Zinc interferes with copper absorption • Presence of vitamins: example, vitamin C enhances absorption of iron

40. Toxicity of Minerals • Trace minerals are more toxic • Result of supplementation • Presence of contaminants in supplements • Look for the United States Pharmacopeia (USP)-approved brands

41. Iron Toxicity • Men in general and older women should avoid multivitamin-mineral supplements with iron because of the risk of iron toxicity

42. Major Minerals

43. Sodium • Table salt (NaCl): 40% sodium, 60% chloride

44. Sodium • 95% of ingested sodium is absorbed • Major positive ion in extracellular fluid • Aldosterone regulates sodium balance • Key for retaining body water • Excretion regulated by the kidneys • Muscle contraction • Conduction of nerve impulses

45. Deficiency of Sodium • Rare • Persistent vomiting/ diarrhea • Excessive perspiration (losing 2-3% of body weight) • Depletion of sodium in the body • Muscle cramp, nausea, vomiting, dizziness, shock, coma • Normally kidney will respond by conserving sodium

46. Correcting Deficiency • Pedialyte for children • Gatorade for adults • Salt foods

47. Dietary Sources of Sodium • Average American eats 4-6 grams sodium in foods and softened water • 20% comes from salt added in cooking or at the table • 35-80% comes from processed foods • 4-27% comes from water (issue at 500 mg level if water contains more than 40 ppm (40 mg or 2 mEq/liter)

48. Sodium Content of Fresh Foods

49. Sodium Content of Processed Foods

50. Sodium Needs • Body only needs 100-200 mg/day • Minimum requirement is 500 mg/day • Daily Value is 2400 mg/day • Typical intake is 4000-7000 mg/day