Chapter 8 WATER AND MINERALS

1. Chapter 8 WATER AND MINERALS

2. Water Life begins in and is sustained by water. You are ~ 60% water. The most indispensable nutrient; animals cannot survive more than 3-7 days without water.

3. Water Functions “Universal” solvent Transports nutrients Removes waste Lubricates Shock absorber **Regulates body temperature

4. Water Water flows freely among the different compartments in the body: Extracellular space – outside cells Intracellular – inside cells Obligatory water loss: urine, feces, sweat and respiration. This must be replaced daily! Fig 8.2

5. FIGURE 8-2: WATER BALANCE—A TYPICAL EXAMPLE. Each day, water enters the body in liquids and foods, and some water is created in the body as a by-product of metabolic processes. Water leaves the body through the evaporation of sweat, in the moisture of exhaled breath, in the urine, and in the feces. FIGURE 8-2: WATER BALANCE—A TYPICAL EXAMPLE. Each day, water enters the body in liquids and foods, and some water is created in the body as a by-product of metabolic processes. Water leaves the body through the evaporation of sweat, in the moisture of exhaled breath, in the urine, and in the feces.

6. Water Intake of water regulated by thirst, output by the kidneys: Dehydration causes concentration of solutes in blood. Concentrated blood is “sensed” by the brain (hypothalamus) that reacts by stimulating the thirst mechanism and the pituitary gland.

7. Water Intake and output cont’d Pituitary gland secretes AntiDiuretic Hormone (ADH) which causes the kidneys to absorb more water. Drinking and increased absorption of water restore balance. **Thirst lags behind water loss and if not recognized dehydration can become serious.

8. Water Water intoxication: Usually reversed by kidneys Problems can occur in people with: Kidney disease Pituitary problems – inappropriate ADH Emotional problems – psychogenic water drinking

9. Water Intake and output cont’d Water needs: depends on food intake, activity level, temperature, humidity, etc. Average 9-13 cups per day. Loss of 5% of body water can cause severe symptoms, Table 8.1. The elderly have a blunted thirst mechanism.

11. Water Sources: All foods & beverages, fig 8.2. Note: beverages containing caffeine or alcohol increase water loss (act as diuretics).

12. FIGURE 8-2: WATER BALANCE—A TYPICAL EXAMPLE. Each day, water enters the body in liquids and foods, and some water is created in the body as a by-product of metabolic processes. Water leaves the body through the evaporation of sweat, in the moisture of exhaled breath, in the urine, and in the feces. FIGURE 8-2: WATER BALANCE—A TYPICAL EXAMPLE. Each day, water enters the body in liquids and foods, and some water is created in the body as a by-product of metabolic processes. Water leaves the body through the evaporation of sweat, in the moisture of exhaled breath, in the urine, and in the feces.

13. Water What water is best? Read pp 269-272. ***Tap water vs. bottled water What about those water coolers and water dispensers??

14. Body Fluids and Minerals Movement of water between compartments is vital. Movement is due to osmosis. Osmosis is the passive diffusion of water from an area where it is in high concentration to an area where it is low in concentration.

15. Body Fluids and Minerals Concentration of water is determined by the concentration of particles in each compartment, fig 8.3. High particle concentration = low water concentration = Hypertonic Low particle concentration = high water concentration = Hypotonic

16. FIGURE 8-3: HOW ELECTROLYTES GOVERN WATER FLOW. Water flows in the direction of the more highly concentrated solution. FIGURE 8-3: HOW ELECTROLYTES GOVERN WATER FLOW. Water flows in the direction of the more highly concentrated solution.

17. Body fluids and Minerals Particles include mineral salts (sodium chloride, potassium chloride, etc.), glucose and proteins. Mineral salts break apart in water releasing their components = ions or electrolytes and each component becomes a separate particle. Ex. NaCl = Na+ + Cl-

18. Body Fluids and Minerals Fluid and Electrolyte balance Body’s cells must use energy (ATP) to maintain the electrolyte distribution across cell membranes, fig 8.4. Maintenance of electrolytes in each fluid compartment helps water distribute properly.

19. FIGURE 8-4: ELECTROLYTE BALANCE. Transport proteins in cell membranes maintain the proper balance of sodium (mostly outside the cells) and potassium (mostly inside the cells). FIGURE 8-4: ELECTROLYTE BALANCE. Transport proteins in cell membranes maintain the proper balance of sodium (mostly outside the cells) and potassium (mostly inside the cells).

20. Body Fluids and Minerals Acid-base balance (pH): Some minerals give rise to acids, other give rise to bases when dissolved in water or plasma. Buffers Kidneys and lungs Proteins

21. Major Minerals, fig 8.1 Calcium – most abundant mineral in our body 99% in bones and teeth Hydroxyapatite Calcium reservoir 1% in body fluid compartments

22. Major Minerals Calcium cont’d Blood calcium is tightly regulated at the expense of bone. Bone density is maximum at age 20 and declines after age 40.

23. Major Minerals Calcium cont’d Requirement – DRI 1000 mg/day, ages 19-50; 1200 mg/day ages over 50, snapshot 8.1. Sources: dairy, green leafy vegetables, sardines with bones.

25. Major Minerals Calcium cont’d Deficiencies: osteomalacia and osteoporosis. May also play a role in some forms of hypertension and preelampsia (complication of pregnancy). Toxicities: constipation, kidney stones

26. Major Minerals Phosphorus – 2nd most abundant mineral 85% in bones and teeth 15% in body fluids

27. Major Minerals Phosphorus cont’d Requirement – DRI 700 mg /day, snapshot 8.2. Sources: dairy, meats and other protein foods. Deficiencies: muscle weakness, bone pain Toxicities: calcification of soft tissues

29. Major Minerals Magnesium in a small quantity 50% in bones, 49% in soft tissues, 1% in body fluids. Cofactor - assists in enzyme activity that releases energy from foods, assembles proteins, etc. Helps strengthen bones/teeth Vital for muscle relaxation. Deficiencies: *cardiovascular problems, hallucinations.

30. Major Minerals Magnesium cont’d Requirement – DRI 310(w) – 400(m) mg/day, snapshot 8.3. Sources: all food groups except fats and oils, some public water supplies. **Processing removes magnesium. Deficiencies are caused by vomiting, diarrhea, alcoholism, protein malnutrition. Toxicities are rare but can cause death: kidney failure, ingestion of Mg-containing medications like antacids.

32. Major Minerals Sodium Part of “table salt” (NaCl) Chief ion regulating extracellular fluid volume. Also essential for muscle contraction and nerve transmission. Easily absorbed from foods, regulated by kidneys. Sodium movement is always followed by water movement.

33. Major Minerals Sodium cont’d Requirements – DRI is 1500 mg/day, ages 19-50; 1300 mg/day, 51-70, 1200 mg/day over 70. **UL 2300 mg/day. Sources: all foods, problem is reducing sodium intake. Lowest in fresh fruits and vegetables, highest in processed foods.

34. Major Minerals Sodium cont’d Excess: associated with hypertension, fig 8.7. Current recommendation is add no more than 1 tsp of salt per day to your food. How can you lower Na intake? Deficiencies: use of diuretics, low sodium diets, heavy exercise – esp. endurance athletes.

35. FIGURE 8-7: SODIUM INTAKES OF U.S. ADULTS. aDRI Tolerable Upper Intake Level (UL). FIGURE 8-7: SODIUM INTAKES OF U.S. ADULTS. aDRI Tolerable Upper Intake Level (UL).

36. Major Minerals Potassium Major ion regulating intracellular fluid volume. Vital for muscle contraction Requirements – DRI 4700 mg/day, snapshot 8.4. Sources: dairy, meats, fruits and vegetables ***No to supplements unless prescribed by a doctor.

38. Major Minerals Chloride Major negative ion accompanying sodium, potassium, etc. Part of hydrochloric acid (HCl) – stomach acid. Major source is “salt”

39. Major Minerals Sulfur – oxidized form is sulfate Part of thiamin and biotin and most proteins (vital for structure). No DRI Sources: protein containing foods

40. Trace Minerals, Table 8.7 Iodine Required for synthesis of thyroid hormones. Sources: seafood, iodized salt, milk. Deficiencies: goiter in adults, cretinism in children. *Allergy

41. Trace Minerals Iron Part of hemoglobin & myoglobin ( in muscles). These compounds store and transport oxygen. Deficiencies: anemia, behavioral problems, pica (eating nonfood items such as clay, ice, dirt, etc.) Overload: tissue damage, infections, cardiovascular disease

42. Trace Minerals Iron cont’d Requirements: DRI – 8 mg/day for men, 18 mg/day for women age 18-51, 27 mg/day pregnant women, snapshot 8.5. Sources: meat, beans, green leafy veges. *Heme vs non-heme iron. Vitamin C increases absorption, tea and coffee decrease absorption.

44. Trace Minerals Zinc Assists in enzyme activity; synthesis of genetic material and heme, growth & development, immune function, vision. Overload – overuse of throat lozenges and cold medicines – especially in children. Overload also decreases iron absorption. Requirements – DRI 8-11 mg/day, snapshot 8.6 Sources: meat and dairy

46. Trace Minerals Selenium Promotes antioxidant chemicals Deficiencies – rare; special type of heart disease Sources: meat, *vegetables and grains

47. Trace Minerals Fluoride Tooth decay resistance, strengthens bone. Sources: **public water supplies, toothpaste ?Toxicities – children swallowing toothpaste.

48. Trace Minerals Chromium Promotes insulin action Requirements – DRI is 50 micrograms/day Sources: liver, whole grains, cheese **No to supplements despite deficiencies. Toxicities: skin eruptions, carcinogen

49. Trace Minerals Copper Helps form hemoglobin & collagen, assists enzymes. Sources: meats, nuts, seeds, *water **No to supplements Others: manganese, molybdenum, cobalt, nickel, silicon, etc.

50. ***Calcium OYO Food Feature – calcium needs and sources Controversy - osteoporosis