Unformatted text preview: Water and Minerals Water Water is the most indispensable nutrient 50%70% of body weight Muscle contains 73% water Intracellular fluid Fat contains ~20% Extracellular fluid Fluid within the cells Fluid outside the cells Functions of Water Body temperature regulation Water absorbs excess heat Body secretes fluid via perspiration Skin is cooled as perspiration evaporates Functions of Water (cont) Removal of body waste via urine Amniotic fluid Saliva Bile Urea excretion Sodium excretion Avoid concentrated urine Joint lubricant Are You Drinking Enough? Recommend 9 cups for women and 13 cups for men as a starting point Free fluid recommendation: 1 ml/Kcal Example: 2,200 Kcal x 1 ml = 2,200 ml ( 9 cups) 1 cup = 240 ml Thirst Mechanism Not reliable Concerns for infants, older adults, athletes Athletes Weigh before and after training session Consume 2 cups for every pound lost Water Loss Urine greatest amount of water loss Stool diarrhea will increase loss Perspiration exercise and heat will increase loss Exhaled air Increased Fluid Needs Illness (vomiting, diarrhea, fever) Hot, humid conditions Exercise High protein diet High fiber diet Caffeine: Diuretic Alcohol: Diuretic Ignoring the Thirst Signal Shortage of water increases fluid conservation Antidiuretic hormone Aldosterone Released by the pituitary gland Forces kidneys to conserve water (reduce urine flow) Responds to drop in blood pressure Signals the kidney to retain sodium (water) *The more water the body needs, the less it excretes Dehydration Thirst: early dehydration Urine color: dark urine, low volume (urine should be pale yellow) 1 lb loss = 2 cups fluid Symptoms: headache, dry mouth, dark urine Advanced dehydration: muscle spasms, sunken eyes, delirium, death Too Much Water Overburden the kidneys Low blood electrolyte concentrations Blurred vision Types of Water Hard water: high in calcium, magnesium Soft water: high in sodium Bottled water Public water systems monitored by EPA 250 10,000x cost of tap water Approx. 1/3 contain contaminants FDA estimates 25% of bottled water sold in U.S. is bottled tap water Less rigorous inspection standards FDA regulates interstate bottled water IBWA supports FDA regulations & enforcement Other Sources of Water Other fluids: Milk, juices, pop, soup Fruits & vegetables Meat, cheese Factors that can affect water balance: Sodium can cause water retention Caffeine, alcohol are diuretics (cause fluid loss) "Waterpills" (diuretic medications) cause increased urinary water excretion Laxatives % Water Content Water Balance Balance between water intake & excretion to ensure constant body water content Dehydration: loss of body water Water intoxication: body water content too high Symptoms: thirst, weakness, fatigue, headache, confusion, exhaustion, delirium, shock, seizures, coma, death Symptoms: headache, muscle weakness, lack of concentration, poor memory, loss of appetite Intake vs. Output Fluid Balance Water shifts freely in and out of cells Osmosis Controlled by electrolyte concentration Intracellular water volume Extracellular water volume Depends on intracellular potassium and phosphate concentrations Depends on extracellular sodium and potassium concentrations Body Fluids and Minerals Cells maintain fluid balance via minerals Ions: electrically charged particles, which carry electrical current (electrolytes) Water moves toward higher ionic concentration to maintain fluid & electrolyte balance (proper amount of fluid within each compartment) Sodium
Found as table salt (NaCl): 40% sodium, 60% chloride (1 tsp of salt = 2,400 mg Na) 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 Needed for water balance (water follows sodium) Sodium Deficiency Deficiency is rare Persistent vomiting/diarrhea Excessive perspiration Depletion of sodium in the body Signs of deficiency: Losing 23% of body weight Normally kidney will respond by conserving sodium Muscle cramp, nausea, vomiting, dizziness, shock, coma Food Sources of Sodium Most sodium is added by food manufacturers and restaurants Most fast food and processed foods Condiments Canned foods Foods prepared in brine (pickles, sauerkraut, olives) Salted or smoked meats (bacon, sausage, deli meat) Salted or smoked fish (smoked salmon, anchovies) Cheese Hypertension (HTN) Systolic blood pressure/Diastolic blood pressure Optimal BP: less than 120/80 mm Hg HTN 95% of all HTN have no clear cause Sustained systolic pressure >139 mm Hg or diastolic pressure >89 mm Hg (primary or essential HTN) Secondary HTN Why Control Blood Pressure? 50 million Americans suffer from hypertension Silent disease (very few symptoms) To prevent: Cardiovascular disease Poor circulation Kidney disease Stroke, decline in brain functions Causes of HTN and Treatment Risk Age Sodium Intake Obesity Physical inactivity Alcohol intake >2/day Family history Treatment < 2300 mg/day Wt loss Exercise 12 glasses day Sodium and Blood Pressure Blood pressure increases with intake Fluid retention leads to increased blood volume Anyone over 51 years of age, of African American descent and/or those that have HTN/DM/CKD should consume < 1,500 mg/day Average intake = 6,000 mg Recommendation = 2,300 mg Whopper with cheese & fries = 2,000 mg Other Minerals and HTN >1000 mg calcium per day lowers blood pressure 24 gm of potassium per day lowers blood pressure Magnesium may lower blood pressure Diet rich in fruits, vegetables (vitamin C) DASH diet (Dietary Approaches to Stop Hypertension) DASH Diet DASH diet: often achieves greater decrease in blood pressure than Na+ restriction alone High in fruits, vegetables, nuts, fish, whole grains and lowfat dairy products Low in red meat, butter, other highfat foods; Na+ intake Sources of sodium to limit: salt shaker 15% of Na+ consumption 75% of Na+ consumption comes from processed foods (pickles, sauerkraut, olives, processed meats, salty snacks, cheese, fast/convenience foods, canned/instant soups, condiments, salted or smoked meats and fish) HTN and the DASH Diet High risk with the following diets: calcium potassium fruit/vegetable in fiber in fat sodium Treatment (DASH diet): calcium potassium fruit/vegetable fiber fat sodium Potassium Positive ion in intracelluar fluid Functions Associated with lowering blood pressure Low blood potassium Fluid balance Nerve impulse transmission 90% of potassium consumed is absorbed Muscle cramps, confusion, constipation, irregular heart beat, heart failure Potassium Sources and Needs Fruits, vegetables, milk, grains, meats, dried beans Adequate Intake is 4700 mg/day Daily Value is 3500 mg/day Typical intake is 20003000 mg/day Diuretics may deplete potassium Excess potassium is excreted by the kidneys; no Upper Level Minerals Various functions in the body Major Minerals Require >100 mg /day Calcium, phosphorus Require < 100 mg/day Iron, zinc Trace Minerals Bioavailability of Minerals Degree of absorption Presence of binders and fiber Animal products are better absorbed Refinement lowers mineral content Mineralmineral competition Vitaminsmineral competition Plants depend on mineral content of soil Calcium The most abundant mineral in the body 99% is stored in bones and teeth Functions in bone: Bone structure (formation and maintenance) Calcium reserve If low blood levels, calcium is taken from the bones; the skeleton serves as a bank from which the blood can borrow and return calcium as needed Calcium and Body Fluids 1% of calcium found in body fluids Functions: 1)Blood clotting 2)Nerve impulse transmission 3)Muscle contraction 4)Cell metabolism 1)Helps maintain normal blood pressure
- Activates various enzymes Blood calcium is tightly controlled Blood Calcium is Regulated Blood level is maintained at the price of bone calcium Blood level can be maintained despite inadequate calcium intake Setting stage for future bone fractures Bone Strength Dependent on bone mass and bone mineral density The more there is, the stronger the bone Bone Formation Bone cells: Remodeling Osteoclasts: (chewing) cells that break down bone Osteoblasts: cells that build bone Bones continually breaking down and rebuilding throughout lifetime Bone Formation (cont) Children: Osteoblasts > Osteoclasts Age 3045: Osteoblasts = Osteoclasts > age 45: Osteoclasts > Osteoblasts Important to build strong, dense bones up until age 30; after age 30 bone density stays the same and eventually we start to lose bone mass Losing bone mass Maintaining bone mass in 30's and 40's Building bone At age 30, peak bone mass is achieved Osteoclast vs. Osteoblast Building Higher Bone Mass Adequate diet Healthy body weight Normal menses Weightbearing physical activity Moderate intakes of protein, phosphorus, sodium, caffeine Nonsmoker Bone Structure Osteoporosis Calcium deficiency Adult bone loss that occurs with aging; bones become porous, fragile "A pediatric disease with geriatric consequences" High calcium intakes early in life, during bone formation, is recommended to achieve peak bone mass Leads to ~1.5 million fractures / year Slender, inactive women who smoke are most at risk Statistics By age 70 can lose 3040% of bone 1 out of 4 women develop osteoporosis 1 out of 8 men develop osteoporosis Osteoporosis (cont) Silent disease until fractures Excessive bone loss High risk of fractures Common fracture sites Wrist Spine (Dowager's hump) Hip Osteoporosis Diagnosis Dual energy xray absorptiometry (DEXA) 2030 minute whole body scan DEXA measurement generates T score: Normal bone density is 0 to 1 T score Low bone mineral density is 1 to 2.4 Osteoporosis is 2.5 or lower Osteoporosis Risk Factors Females Menopause Less overall bone mass Lower estrogen levels = decreased calcium absorption Low calcium intake Smokers Alcohol intake = increased calcium Osteoporosis Risk Factors (cont) excretion Inactivity Poor vitamin D status Genetics Underweight Carrying a little extra weight may build stronger bones Risk Factors for Osteoporosis Osteoporosis Prevention Adequate calcium and vitamin D intake Weight bearing exercise No smoking Walking, lifting weights Moderate alcohol intake Food Sources of Calcium Calcium Absorption Rates Calcium Supplements Recommended for people who cannot incorporate calcium into their diets Not recommended with highzinc meal Calcium carbonate (40% calcium) Calcium citrate (21% calcium) For those with ample stomach acid Found in antacids Enhances absorption due to acidity content Recommended for older adults Medications Inhibit osteoclast activity Side effects: Ulcers Swallowing difficulties Phosphorus Second most abundant mineral in the body Major ion of intracellular fluid Bone and tooth strength Component of various compounds Role in acid/base balance Absorption is based on body's need (70%90%) No disease associated with deficiency May contribute to bone loss in older women Vitamin D enhances absorption ATP, cell membrane, enzymes, DNA Magnesium Absorption based on body's needs (normally 40%60%) Kidneys regulate blood concentration of magnesium 60% is stored in the bones Functions of Magnesium Aids in many enzyme reactions Potassium and calcium metabolism Proper nerve and cardiac functions Insulin release from the pancreas May dilate arteries May prevent heart rhythm abnormalities Decrease blood pressure Magnesium Sources Magnesium is easily lost with processing washing, peeling Best sources from slightly processed/unprocessed foods Hard tap water Dairy, chocolate, meat Whole grains, vegetables, nuts, seeds Magnesium Food Sources Fluoride Role in prevention of dental caries Helps tooth enamel resist acid Inhibits bacterial growth (suppresses metabolism of bacteria present in plaque) Fluoride Sources and Needs Fluoridated water Tea, seafood, seaweed Toothpaste ~0.2 mg/cup 1 ppm Fluoride Toxicity Mottling of teeth in children Limit toothpaste to pea size for children High amounts can weaken teeth Iron 1) Hemoglobin Most iron is in two proteins:
Iron containing protein in Red Blood Cells Transports oxygen and carbon dioxide High turnover, high demand for iron In muscle cells Carries and stores oxygen for the muscles 2) Myoglobin Food Sources of Iron Absorption of Iron Determined by body's need Iron storage in intestinal cells Absorbed in an acidic environment Hindered by phytic acid, oxalic acid, high fiber, high calcium, polyphenols Iron Absorption Found in minute amounts in every cell 18% is absorbed Iron occurs in 2 forms in foods: Factors that increase iron absorption: Factors that hinder iron absorption: Coffee, tea (tannins) Milk: calcium, phosphorus Fiber (phytates) MFP factor, vitamin C 1) Heme iron, Nonheme iron 2) Heme iron more readily absorbed Cooking in iron pan can increase iron content of food Supplemental iron not as well absorbed as iron from food IronDeficient Anemia Most common form of anemia Low levels of hemoglobin and hematocrit; RBC's become small & pale Insufficient intake and stores Reduction in: Production of red blood cells Oxygencarrying capacity Anemia Groups at Risk for Deficiency Most at risk: Infant, toddler Chronic blood loss Vegans Runners Women of childbearing years Monthly blood loss High rate of growth Poor intake Signs and Symptoms Tired, paleness, brittle nails, fatigue Rapid heart beat Poor growth Pica Poor temperature control Consumption of nonfood items (such as clay, ice, paste, stones, cigarette butts, chalk, tire inner tubes, etc) Pica Pica is seen in chimpanzees, and in humans since ancient times Health risks associated with eating nonfood substances Young children and pregnant women are most likely to practice Pica Individuals living in rural areas Family history Rarely occurs in men Pica Theories Relieves nausea Most commonly during pregnancy Deficiency of essential nutrient Misconceptions Iron deficiency Clay helps baby slide out ??? Geophagia Some people eat clay or dirt Report it tastes or smells good, quells a craving, relieves nausea or upset stomach No evidence that geophagia is motivated by a need for minerals Consequences to health are serious Clay and dirt can block the intestinal tract and cause parasitic and bacterial infections Pagophagia Regular ice eating is associated with an irondeficient state Ice eating usually stops completely when the iron deficiency is treated Ice eating is common during pregnancy One study found ice eaters had poorer iron status than pregnant women who did not eat ice Amylophagia Sweet taste and crunchy texture of flaked laundry starch attracts a small number of women during pregnancy If laundry starch is not available, cornstarch may be used Taste for starch always disappears after pregnancy Starch eating provides calories and may reduce the intake of nutrientdense foods Starch may contain contaminants Starch eaters' diets inferior to diets of pregnant women who don't consume starch Plumbism Leadcontaining paint chips pose a major threat to the health of children Older homes and buildings are covered with leadbased paint and its flakes Children develop lead poisoning if they eat the sweet paint flakes or inhale lead from contaminated dust and soil near the buildings One million young children have elevated blood lead levels Plumbism (cont) High levels of lead cause mental retardation and death in young children Low exposure leads to hearing problems, growth retardation, reduced intelligence, and poor classroom performance Children with lead poisoning are likely to fail or drop out of school Complications of Pica Intestinal blockages Bacterial infections Parasites Damage to teeth Stages of Iron Deficiency Iron Needs RDA is 10 mg/day for adult male RDA is 15 mg/day for female age 19 to 50 Iron Toxicity Once absorbed, iron is difficult to excrete Serious condition, especially for children Signs: #1 cause of fatal poisoning in children < 3 years of age (often from supplements) Diarrhea, constipation, nausea, abdominal pain Causes death due to respiratory collapse (shock) Genetic defect disease Iron deposit that can lead to organ damage May go undetected until organ damage at 5060 Hemochromatosis Iron is a powerful oxidant; high iron stores may be related to CVD development Copper Aids in iron metabolism Increases iron absorption Aids in formation of connective tissue Assists immune system, blood clotting, brain development, cholesterol metabolism Copper Food Sources Copper Deficiency Anemia Decreased WBC Bone loss Inadequate growth Functions of Zinc Cofactor to many enzymes DNA synthesis and function Growth, protein metabolism, wound healing Taste perception Immune function Cell membrane structure and function Development of sexual organs and bones Insulin function Zinc Absorption Absorption Factors that decrease absorption Influenced by the foods consumed Animal sources are better absorbed Dependent on body's need Presence of phytic acid Competes with copper and iron for absorption Food Sources of Zinc Zinc Deficiency Zinc deficiency impairs all of these functions: Mild deficiency can result in impaired immunity, abnormal taste, abnormal night vision Deficiencies can occur in pregnant women, young children, elderly, poor Altered digestive function (severe diarrhea) Decreased immunity (increased infections) Disturbed thyroid function, decreased energy metabolism, decreased appetite Slow wound healing Decreased physical activity, memory, attention span Zinc Toxicity Inhibits copper metabolism Possibly increases risk for prostate cancer Causes diarrhea, cramps, nausea, vomiting Depresses immune function Selenium Readily absorbed Functions: Excreted through the urine and feces Thyroid hormone metabolism Antioxidant Protects the heart and other cells from oxidative damage Works together with vitamin E Selenium Toxicity Upper Level is 400 ug/day Garlicky breath Hair loss Nausea, vomiting Weakness Rashes Cirrhosis of the liver Iodine Iodine in foods fortified salt Functions: Deficiency: Supports thyroid hormone (thyroxine) synthesis Regulates metabolic rate, growth, development Thyroid gland enlarges (goiter) due to low intake Cretinism: stunting of fetal growth and mental development as a result of low iodine in maternal diet Iodine Toxicity Upper Level is 1.1 mg/day Thyroid hormone synthesis is inhibited "Toxic goiter" results Consumption of seaweed poses risk Chromium Enhances insulin action Low intake: Role in Type 2 diabetes? Impaired glucose tolerance Elevated blood cholesterol and triglycerides Chromium Diets high in simple sugars and low in whole, nutrientdense foods deplete chromium Chromium supplements do not build muscle or decrease fat Chromium widely distributed in foods: A complex of biologically active chromium with other compounds in foods leads to improved glucose tolerance factor Lost during food processing, refinement Sources include liver, whole grains, nuts, cheese ...
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- Spring '08
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