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3/15/16 Water: Crucial to Life Water and Minerals: The Ocean Within BIOL 103, Chapter 8 SP 2016 • Water is the most essenEal nutrient – 45–75% body weight – Body water • 2/3 Intracellular • 1/3 Extracellular Water: Crucial to Life • Electrolytes and water – When minerals or salts dissolve in water à form ions: • CaEons • Anions – Osmosis 1 3/15/16 Intake RecommendaEons • How much water is enough? – Men = 3.7 liters/day AI – Women = 2.7 liters/day AI – Pregnancy = 3.0 liters/day AI – LactaEon = 3.8 liters/day – Increased needs for acEvity and sweaEng Intake RecommendaEons • Sources – 75-‐80% from Beverages – 20-‐25% from Foods – Small amount from metabolic reacEons (250-‐350mL/day) Water ExcreEon: Where Does the Water Go? 1. Insensible water losses: the conEnuous loss of body water by evaporaEon from the lungs and diffusion through skin. – ¼-‐ ½ of daily fluid loss 2. Urine (~1-‐2 liters per day) 3. Illness 4. External factors that contribute to water losses: – Low humidity – High alEtude – High protein/salt foods 2 3/15/16 Intake RecommendaEons • Water Balance – Bodies carefully maintain water balance 1. Hormonal effects • An1diure1c hormone (ADH) • Aldosterone 2. Thirst 3. Alcohol, caffeine, and common medicaEons affect fluid balance Water Balance • Alcohol, caffeine, and common medicaEons are usually diure1cs – Alcohol and caffeine are able to inhibit the release of ADH (by the pituitary gland) – Too much alcohol/ caffeine can lead to dehydraEon Water Balance – How do kidneys know how to conserve water? 1. Spinal cells in brain sense rising sodium levels in the body à signals pituitary gland to release ADH à signals kidneys to conserve water à water reabsorpEon dilutes sodium levels 2. Sensors in the kidneys detect a drop in blood pressure à adrenal glands release aldosterone à kidneys retain sodium à water follows sodium à water reabsorpEon Intake RecommendaEons • DehydraEon – Early signs: FaEgue, headache, and dark urine with strong odor – Water loss of 20% can cause coma and death – Seniors and infants especially vulnerable – Treatment: water consumpEon (with electrolytes) or IV (moderate to severe cases) 3 3/15/16 Water IntoxicaEon Understanding Minerals • Water intoxicaEon: – Can occur in people who drink too much water – Over-‐hydraEon can also occur in people with untreated glandular disorders that cause excessive water retenEon – Deionized water (without minerals/ electrolytes) – Causes low blood sodium à headaches à seizures à coma à death • Minerals – Inorganic – Not destroyed by heat, light, acidity, alkalinity – Micronutrients (needed in small amounts) – Grouped as: 1. Major minerals (>100 mg/day) 2. Trace minerals (<100 mg/day) Minerals in Foods • Found in plant (soil) and animal (diet) foods • Found in drinking water: sodium, magnesium, fluoride • Mineral absorpEon limited by several factors: 1. GI tract 2. CompeEng minerals (ex. megadose) 3. High-‐fiber diet contain phytates (iron, zinc, manganese, calcium) 4. Oxalate (calcium) 4 3/15/16 Major Minerals and Health • Mineral status significantly affects health • Play criEcal parts in hypertension and osteoporosis Sodium • FuncEons: 1. Fluid balance, blood pressure, and pH 2. Nerve impulse transmission • Food sources – Processed and convenience foods – Added (table) salt Sodium • Dietary RecommendaEons – Daily intake less than 2,400 mg/day – Daily intake less than 1,500 mg/day desirable • Dealing with Excess Sodium – Can contribute to hypertension – Can worsen dehydraEon Potassium • FuncEons: 1. Muscle contracEon 2. Nerve impulse transmission 3. Regulates blood pressure and heartbeat • Food sources: – People who eat low-‐sodium, high potassium diets omen have lower blood pressure – Vegetables and fruits such as potatoes, spinach, melons, bananas – Meat, poultry, fish, dairy products 5 3/15/16 Potassium • Dietary RecommendaEons – AI: 4,700 mg/day • Deficiency – Likely factor in hypertension risk – Can disrupt acid-‐base balance • Toxicity – Rare – High levels can slow heart Calcium • FuncEons – Bone structure • Hydroxyapa1te • Bone cells – Osteoblasts – Osteoclasts • Reserve of calcium and phosphorus Chloride • FuncEons: 1. Fluid balance (blood, sweat, tears) 2. Hydrochloric Acid (stomach acid) • Food sources: – Table salt (NaCl – sodium chloride) • Deficiency: – Excessive vomiEng (ex. Bulimia nervosa) Calcium • FuncEons – Muscles and metabolism • Flow of calcium causes muscles to contract or relax – Other funcEons • Blood clonng • Nerve impulse transmission 6 3/15/16 Calcium Calcium • RegulaEon of blood calcium levels – Calcitriol/Vitamin D – Parathyroid hormone – Calcitonin • Dietary RecommendaEons – RDA: 1,300 mg/day (children 9-‐18) – RDA: 1,000 mg/day (men 19-‐70; women 19-‐50) – RDA: 1,200 mg/day (men 70+; women 51+) • RegulaEon of blood calcium levels by three hormones: – To prevent dips in blood calcium levels, your body will demineralize bone – If low blood calcium levels à calcitriol increases intesEnal absorpEon of calcium, and parathyroid hormone (PTH) acEvates osteoclasts to release bone calcium – If high blood calcium levels à thyroid glands release calcitonin to reduce blood calcium RegulaEon of Blood Calcium Calcium • Food Sources – Dairy products, green vegetables, processed and forEfied foods – Oxalate—binds calcium – Calcium supplementaEon will not interfere with absorpEon of other minerals, but can interfere with absorpEon of some medicaEons 7 3/15/16 Phosphorus • FuncEons – Bone structure – Component of ATP, DNA, RNA, and phospholipids • Food sources – Milk, eggs, beans, lenEls – Processed foods • Phosphate balance – Too much phosphorus and too lisle calcium = increased bone loss Magnesium • FuncEon – ParEcipates in more than 300 types of enzyme-‐driven reacEons • Food sources – Whole grains, vegetables, legumes, tofu, seafood, and chocolate Magnesium Sulfur • FuncEon: – ParEcipates in more than 300 types of enzyme-‐driven reacEons, including energy metabolism, blood clonng, muscle contracEon, DNA and protein synthesis • Food sources: – Whole grains, vegetables, legumes, tofu, seafood, and chocolate • Magnesium balance – We absorb ~50% of dietary magnesium – At risk for deficiency: chronic diarrhea, poor diet, and heavy alcohol use. • FuncEon: – Primarily a component of organic nutrient, including other vitamins/amino acids – Help proteins maintain their funcEonal shapes • Food sources: – Typical diets contain ample sulfur • Deficiency: – Unknown 8 3/15/16 Trace Minerals • Trace Minerals: – Iron, Zinc, Selenium, Iodine, Copper, Manganese, Fluoride, Chromium, Molybdenum • Cofactors for enzymes • Components of hormones • ParEcipate in many chemical reacEon • EssenEal for: – Growth – Immune System Iron Iron and Hemoglobin • FuncEons – Oxygen transport as part of hemoglobin and myoglobin – Cofactor for enzymes involved in energy producEon, immune funcEon, and normal brain/nervous system funcEon 9 3/15/16 Nerve Cells Iron • Iron AbsorpEon – Effect of Iron Status • AbsorpEon varies – Effect of GI FuncEon • Depends on stomach acid/HCl – Effect of the Amount and Form of Iron in Food • Conserve iron – Heme iron (animal) – Non-‐heme iron (plant/animal) Iron Iron • Iron absorpEon – Dietary Factors Enhancing Iron AbsorpEon • Vitamin C – Dietary Factors InhibiEng Iron AbsorpEon • Phytate & oxalates bind to non-‐heme iron • Calcium, zinc, and iron compete for absorpEon • Iron Transport and Storage – Transferrin ferries iron through blood – Most iron stored as ferri1n in body – Smaller amounts stored as hemosiderin 10 3/15/16 Iron • Iron Turnover and Losses Iron – RouEne destrucEon of old red blood cells releases iron à recycled to build new red blood cells – Dietary iron especially important in Emes of rapid growth and blood expansion (infant à young children) – Lose iron in feces, sweat, skin cells, and menstruaEon – DigesEve disorders/blood loss increase iron losses • Food sources: – Red meat, oyster, legumes, tofu, whole grains • Deficiency: – Most common deficiency worldwide – Iron-‐deficiency anemia • Toxicity: – Adult doses can cause poisoning in children – Hereditary hemochromatosis – a geneEc disorder in which excessive absorpEon of iron results in abnormal iron deposits in the liver and other Essues. Zinc Zinc • FuncEons – Serves as cofactor for major enzymes – Helps fold proteins into funcEonal shapes – Helps control diverse funcEons, including gene expression, cell death, and nerve transmission • Enzymes – Helps provide structural integrity or acEvate catalyEc ability • Gene regulaEon – Enables proteins to fold into a special form that interacts with DNA • Immune system – Vital to fighEng infecEon 11 3/15/16 Zinc • RegulaEon of Zinc in the Body – AbsorpEon • Similar to iron • Only about 10-‐35% of zinc absorbed • Phytate inhibits absorpEon – Transport, distribuEon, and excreEon • Circulates bound to protein Zinc • Deficiency – Uncommon but may occur in people with illnesses that impair absorpEon • Poor growth and delayed development – Zinc deficiency lowers immunity; infecEon causes zinc loss RegulaEon of Zinc in the Body • AbsorpEon: – ~10-‐35% of zinc in diet – Depends on body’s needs, zinc content of the meal, and presence of compeEng minerals – Phytate and supplemental calcium inhibit absorpEon • Transport, distribuEon, and excreEon: – Zinc circulates in the bloodstream bound to protein, traveling to the liver and Essues. • Food sources: – Red meats, seafood Iodine • FuncEon: Thyroid hormone producEon – Thyroid hormone helps regulate body temperature, basal metabolic rate, reproducEon, and growth • Food sources: – Iodized salt, saltwater fish, seafood, seaweed • Toxicity – Usually rare – Chronic doses may induce copper deficiency 12 3/15/16 Iodine Iodine and Thyroid Gland • Deficiency: – Goiter: enlarged thyroid gland – Cre1nism: mental retardaEon, stunted growth, deafness, muteness • Occurs in fetus if pregnant woman is deficient • Toxicity: – Goiter Selenium • FuncEons: 1. Part of anEoxidant enzyme 2. Thyroid metabolism: convert thyroid hormone to its most acEve form • AbsorpEon: – Enhance absorpEon: Vitamins A, C, E – Inhibits absorpEon: Phytates 13 3/15/16 Selenium • Food sources – Organ meats, fish, seafood, meats, Brazil nuts • Deficiency – Increases suscepEbility to some infecEons – Can worsen hypothyroidism • Toxicity – Brisle hair and nails Copper • Food Sources – Organ meats, shellfish, nuts, and legumes • Deficiency – Causes anemia and poor immune funcEon • Toxicity – RelaEvely nontoxic Copper • FuncEons – Melanin, collagen, and elasEn producEon – Immune funcEon – AnEoxidant enzyme – Works with ceruloplasmin, a copper-‐ dependent enzyme required for iron transport • AbsorpEon and Storage – Varies from 20% to 50% – Interferes with absorpEon: Iron, Zinc Manganese • FuncEons – CarElage producEon – AnEoxidant enzyme systems/MnSOD • Food Sources – Tea, nuts, cereals 14 3/15/16 Manganese • Deficiency – High calcium, magnesium, iron diets can interfere with manganese absorpEon • Toxicity – Incidents due to air pollutants • Symptoms: hallucinaEons, memory/ motor coordinaEon. Fluoride • FuncEons – Bone and tooth structure • Food sources – Fluoridated water • Balance – Excess can cause fluorosis: discoloraEon and “specks” on teeth; weakens teeth. • The fluoridaEon debate Chromium Molybdenum • FuncEons: – Glucose metabolism • Enhances insulin’s ability to move glucose into cells. • Food sources: – Mushrooms, dark chocolate, nuts, whole grains • Deficiency and toxicity: – Difficult to determine deficiency – No UL • FuncEons: – Enzyme cofactor (e.g. ADH) • Food sources – Peas, beans, organ meats, some breakfast cereals • AbsorpEon: – Inhibit: Copper • Deficiency/Toxicity: – Deficiency: Rare – Toxicity: Unlikely 15 3/15/16 Other Trace Minerals and Ultratrace Minerals • Arsenic • Boron • Nickel • Silicon • Vanadium 16