water the water in body fluids: carries nutrients and waste products throughout the body carries...
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WATERWATERThe water in body fluids:The water in body fluids:• Carries nutrients and waste products throughout Carries nutrients and waste products throughout
the bodythe body• Maintains the structure of large molecules such as Maintains the structure of large molecules such as
proteins and glycogenproteins and glycogen• Participates in metabolic reactionsParticipates in metabolic reactions• Aids in regulation of body temperatureAids in regulation of body temperature• Maintains blood volume and pH balanceMaintains blood volume and pH balance• Acts as a lubricant and cushion around joints and Acts as a lubricant and cushion around joints and
inside eyes, and the spinal cordinside eyes, and the spinal cord
ELECTROLYTESELECTROLYTES• Water in the body contains numerous dissolved Water in the body contains numerous dissolved
minerals, called electrolytes, that are kept in minerals, called electrolytes, that are kept in constant balanceconstant balance
• When salts, such as NaCl, dissolve in water, they When salts, such as NaCl, dissolve in water, they break apart into + and – ionsbreak apart into + and – ions
• + = cations (sodium and potassium)+ = cations (sodium and potassium)• - = anions (chloride and phosphate)- = anions (chloride and phosphate)• Unlike pure water which conducts electricity Unlike pure water which conducts electricity
poorly, ions dissolved in water carry an electrical poorly, ions dissolved in water carry an electrical current, hence they are called electrolytescurrent, hence they are called electrolytes
ELECTROLYTESELECTROLYTES
Na+ is the major cation in the extracellular Na+ is the major cation in the extracellular fluid, K+ is the predominant cation in the fluid, K+ is the predominant cation in the intracellular fluidintracellular fluid
ELECTROLYTESELECTROLYTES
• The balance of body fluids and the amount The balance of body fluids and the amount of electrolytes are controlled preciselyof electrolytes are controlled precisely
• In an electrolyte solution, the amount of + In an electrolyte solution, the amount of + charges always equals the amount of charges always equals the amount of negative chargesnegative charges
• Whenever Na+ leaves a cell, other +ions Whenever Na+ leaves a cell, other +ions enter (like K+) enter (like K+)
• Whenever electrolytes move across the cell Whenever electrolytes move across the cell membrane, water followsmembrane, water follows
WATER EXCRETIONWATER EXCRETION• Our body loses water through: the skin, lungs, Our body loses water through: the skin, lungs,
feces (very little), urinefeces (very little), urine• Depending upon the amount of protein, water, and Depending upon the amount of protein, water, and
sodium consumed, we lose 1-2L each day through sodium consumed, we lose 1-2L each day through the urinethe urine
• Insensible water loss accounts for ~ ¼ to ½ of Insensible water loss accounts for ~ ¼ to ½ of daily fluid lossdaily fluid loss
• Losses increase in: exercise, high altitude, low Losses increase in: exercise, high altitude, low humidity, high temperatures, illness (coughing, humidity, high temperatures, illness (coughing, fever, rapid breathing, and watery nasal fever, rapid breathing, and watery nasal secretions)secretions)
Regulation of Fluid ExcretionRegulation of Fluid Excretion
• The kidneys adjust the amount and concentration The kidneys adjust the amount and concentration of urine in response to the body’s hydration statusof urine in response to the body’s hydration status
• Low water intake = low volume of concentrated Low water intake = low volume of concentrated urineurine
• High water intake = high volume of diluted urineHigh water intake = high volume of diluted urine• Osmoreceptors and antidiuretic hormone (ADH) Osmoreceptors and antidiuretic hormone (ADH)
work together to regulate water excretionwork together to regulate water excretion
THIRSTTHIRST
• Thirst is not always a reliable guide to Thirst is not always a reliable guide to avoiding dehydrationavoiding dehydration
• Athletes, elderly people, and infants are Athletes, elderly people, and infants are vulnerable to dehydrationvulnerable to dehydration
• How can we avoid dehydration?How can we avoid dehydration?
From the International Journal of From the International Journal of Sports NutritionSports Nutrition
• Researchers concluded that “urine color Researchers concluded that “urine color may be used in athletic/industrial settings to may be used in athletic/industrial settings to determine whether a subject is adequately determine whether a subject is adequately hydrated”hydrated”
• Suggested that athletes (and others) should Suggested that athletes (and others) should seek to produce urine that is “very pale seek to produce urine that is “very pale yellow” or “straw-colored” yellow” or “straw-colored”
WATER INTAKE WATER INTAKE RECOMMENDATIONSRECOMMENDATIONS
• There is no RDA for waterThere is no RDA for water• General recommendation: 1 to 1.5 mL per General recommendation: 1 to 1.5 mL per
kcals expended (2400 kcal = 2400 mL or kcals expended (2400 kcal = 2400 mL or 2.4 litres)2.4 litres)
• Equals ~ 9.6 cups of water per dayEquals ~ 9.6 cups of water per day
WATER SOURCESWATER SOURCES
• Hydrating beverages: water, milk, fruit Hydrating beverages: water, milk, fruit juice, herbal tea, most foods (especially juice, herbal tea, most foods (especially fruits and vegetables)fruits and vegetables)
• Dehydrating beverages: alcohol, caffeinated Dehydrating beverages: alcohol, caffeinated beverages (coffee, tea, some soft drinks)beverages (coffee, tea, some soft drinks)
• Are Americans chronically dehydrated?Are Americans chronically dehydrated?
Per capita median intake of Per capita median intake of waterwater
672 ml (2.8 cups)672 ml (2.8 cups)
Per capita milk intakePer capita milk intake 312 ml (1.3 cups)312 ml (1.3 cups)
Per capita coffee and tea Per capita coffee and tea intakeintake
360 ml (1.5 cups)360 ml (1.5 cups)
Per capita soft drink intakePer capita soft drink intake 420 ml (1.75 cups)420 ml (1.75 cups)
Total per capita fluid Total per capita fluid comsumptioncomsumption
1764 ml (7.35 cups)1764 ml (7.35 cups)
What are the effects of chronic What are the effects of chronic dehydration? dehydration?
• Diminished physical performanceDiminished physical performance• Diminished mental performanceDiminished mental performance• Diminished salivary gland functionDiminished salivary gland function• Increased risk of urinary tract, colon, and Increased risk of urinary tract, colon, and
breast cancer*breast cancer*
• Is it possible to take in too much water?Is it possible to take in too much water?
HYPONATREMIA: Low concentration of HYPONATREMIA: Low concentration of sodium in the bloodsodium in the blood
• Symptoms: can range from mild to severe Symptoms: can range from mild to severe and can include nausea, muscle cramps, and can include nausea, muscle cramps, disorientation, slurred speech, confusion, disorientation, slurred speech, confusion, and inappropriate behaviorand inappropriate behavior
• Seizures or coma, and death can occurSeizures or coma, and death can occur
Do we need to replace Do we need to replace electrolytes during exercise?electrolytes during exercise?
DIURETICSDIURETICS
• A diuretic is any substance that increases A diuretic is any substance that increases fluid loss through increased urinationfluid loss through increased urination
• Alcohol and caffeine act as diuretics by Alcohol and caffeine act as diuretics by inhibiting ADH activityinhibiting ADH activity
MAJOR MINERALS: SodiumMAJOR MINERALS: Sodium
• Sodium acts in concert with potassium Sodium acts in concert with potassium and chloride to maintain proper body and chloride to maintain proper body water distribution and blood pressurewater distribution and blood pressure
• Sodium also helps to maintain acid-Sodium also helps to maintain acid-base balance, nerve transmission, base balance, nerve transmission, muscle function, and absorption of muscle function, and absorption of nutrients such as glucosenutrients such as glucose
SODIUM: SourcesSODIUM: Sources
• Most of the sodium in our diet comes from Most of the sodium in our diet comes from processed foods (75%)processed foods (75%)
• The other sources are natural sodium in The other sources are natural sodium in foods (10%) and salt added during cooking foods (10%) and salt added during cooking and eating (15%)and eating (15%)
SODIUM: RequirementsSODIUM: Requirements
Estimated Estimated minimum minimum requirement for requirement for sodium: 500 mg/daysodium: 500 mg/day
Recommended Recommended maximum maximum intake of salt: 6 intake of salt: 6 g/day (2400 mg sodium).g/day (2400 mg sodium).
– 5 g salt = about 2 g sodium5 g salt = about 2 g sodium
– 3 g salt = 1.2 tsp3 g salt = 1.2 tsp
HYPERTENSION HYPERTENSION Chronic High Blood PressureChronic High Blood Pressure
• Hypertension injures the artery linings and Hypertension injures the artery linings and accelerates plaque formationaccelerates plaque formation
• Plaques and reduced blood flow induce a further Plaques and reduced blood flow induce a further rise in blood pressure, and HTN and rise in blood pressure, and HTN and atherosclerosis become mutually aggravating atherosclerosis become mutually aggravating conditionsconditions
• Diagnosis: diastolic pressure >90mmHg and/or Diagnosis: diastolic pressure >90mmHg and/or systolic pressure >140mmHg (men) and systolic pressure >140mmHg (men) and >160mmHg (women)>160mmHg (women)
• These values are associated with an increase in These values are associated with an increase in mortality of over 50%mortality of over 50%
SODIUM and HYPERTENSIONSODIUM and HYPERTENSION
• Our bodies are poorly adapted to handle our Our bodies are poorly adapted to handle our modern high sodium, low potassium diets. modern high sodium, low potassium diets. (The (The diet of our ancestors is estimated to have diet of our ancestors is estimated to have contained contained 16 times16 times more potassium than sodium.) more potassium than sodium.)
• About 10-15% of people with hypertension are About 10-15% of people with hypertension are “salt-sensitive”. If these people decrease their “salt-sensitive”. If these people decrease their sodium intake, their BP decreasessodium intake, their BP decreases
• For non “salt-sensitive” people, reducing salt For non “salt-sensitive” people, reducing salt intake has a minimal effect on BPintake has a minimal effect on BP
HYPERTENSIONHYPERTENSION
Other Dietary Factors:Other Dietary Factors:• Excess weight tends to raise BP, exercise Excess weight tends to raise BP, exercise
and weight loss help to reduce itand weight loss help to reduce it• Alcohol consumption can increase BPAlcohol consumption can increase BP• Diets rich in calcium, magnesium, and Diets rich in calcium, magnesium, and
potassium help to reduce BPpotassium help to reduce BP
POTASSIUMPOTASSIUM
• Like sodium, potassium is important in Like sodium, potassium is important in regulation of blood pressure, nerve regulation of blood pressure, nerve transmission, muscle contractions, transmission, muscle contractions, electrolyte balance, and cell integrityelectrolyte balance, and cell integrity
POTASSIUM: Sources POTASSIUM: Sources
• Good sources include fresh fruits and Good sources include fresh fruits and vegetables, especially bananas, potatoes, vegetables, especially bananas, potatoes, spinach, legumes, squash, and melonsspinach, legumes, squash, and melons
• Fresh meat, milk and yogurt, coffee and tea Fresh meat, milk and yogurt, coffee and tea are other good sourcesare other good sources
FUNCTIONS of IRONFUNCTIONS of IRON
OXYGEN TRANSPORTOXYGEN TRANSPORT• Most of the body’s iron is found in two Most of the body’s iron is found in two
proteins: hemoglobin and myoglobinproteins: hemoglobin and myoglobin• In both, iron helps to accept, carry, and In both, iron helps to accept, carry, and
then release oxygenthen release oxygen• Hemoglobin in RBCs transports Hemoglobin in RBCs transports
oxygen to the bloodoxygen to the blood• Myoglobin facilitates the movement of Myoglobin facilitates the movement of
oxygen into muscle cellsoxygen into muscle cells
FUNCTIONS of IRONFUNCTIONS of IRON
ENZYMESENZYMES• Iron is a component of enzymes involved in Iron is a component of enzymes involved in
energy metabolism (cytochromes are heme-energy metabolism (cytochromes are heme-containing compounds in the ETC)containing compounds in the ETC)
• Iron is also required by enzymes involved Iron is also required by enzymes involved in the making of amino acids, collagen, in the making of amino acids, collagen, hormones, and neurotransmittershormones, and neurotransmitters
• It is also a cofactor for antioxidant enzymes It is also a cofactor for antioxidant enzymes
FUNCTIONS of IRONFUNCTIONS of IRON
IMMUNE FUNCTIONIMMUNE FUNCTION• Iron is necessary for optimal immune Iron is necessary for optimal immune
functionfunction• Iron deficiency decreases concentrations of Iron deficiency decreases concentrations of
lymphocytes, natural killer cells, and other lymphocytes, natural killer cells, and other immune factorsimmune factors
• Iron overload can worsen an infection Iron overload can worsen an infection because it serves a nutrient for bacteria because it serves a nutrient for bacteria
OTHEROTHER• Iron is used by brain cells for normal Iron is used by brain cells for normal
function at all ages: in the synthesis of function at all ages: in the synthesis of neurotransmitters, and possibly a role in neurotransmitters, and possibly a role in myelinizationmyelinization
• Synthesis of niacin from tryptophan, Synthesis of niacin from tryptophan, carnitine synthesiscarnitine synthesis
FUNCTIONS of IRONFUNCTIONS of IRON
IRON IN THE BODYIRON IN THE BODY
• More than 80% of the body’s functional More than 80% of the body’s functional iron is found in the RBCs, and the rest is in iron is found in the RBCs, and the rest is in myoglobin and enzymesmyoglobin and enzymes
• The body regulates its iron status by The body regulates its iron status by balancing absorption, transport, storage, and balancing absorption, transport, storage, and losses losses
IRON ABSORPTIONIRON ABSORPTION
• Iron absorption in the gastrointestinal tract Iron absorption in the gastrointestinal tract is the primary regulator of iron levelsis the primary regulator of iron levels
• It depends upon:It depends upon:• Normal GI functionNormal GI function• The amount and kind of iron consumedThe amount and kind of iron consumed• Dietary factors that effect iron absorptionDietary factors that effect iron absorption
IRON ABSORPTIONIRON ABSORPTION
• Absorption can vary from less than 1% to Absorption can vary from less than 1% to greater than 50% depending upon:greater than 50% depending upon:
• Body iron storesBody iron stores• Certain conditions – pregnancy, blood loss, Certain conditions – pregnancy, blood loss,
menstruationmenstruation• Gender – men absorb less than womenGender – men absorb less than women
IRON ABSORPTIONIRON ABSORPTION• Foods contain two types of iron – heme and Foods contain two types of iron – heme and
non-heme non-heme • Heme iron is supplied by animal foods which Heme iron is supplied by animal foods which
also contain non-heme iron (~40% heme, 60% also contain non-heme iron (~40% heme, 60% non-heme)non-heme)
• Plant based foods contain only non-heme ironPlant based foods contain only non-heme iron• Heme iron is 2 to 3 times more absorbable than Heme iron is 2 to 3 times more absorbable than
non-heme ironnon-heme iron• People with severe iron deficiency absorb both People with severe iron deficiency absorb both
heme and non-heme iron more efficientlyheme and non-heme iron more efficiently
IRON ABSORPTIONIRON ABSORPTION
Dietary FactorsDietary Factors• Organic acids (like Vitamin C) and Organic acids (like Vitamin C) and
meat boost absorption of non-heme meat boost absorption of non-heme ironiron
• Phytates, polyphenols (found in tea and Phytates, polyphenols (found in tea and coffee), oxalates (spinach), calcium coffee), oxalates (spinach), calcium and phosphorus, EDTA (food and phosphorus, EDTA (food additive), and fiber inhibit non-heme additive), and fiber inhibit non-heme absorptionabsorption
IRON TURNOVER and LOSS IRON TURNOVER and LOSS
• The body recycles iron, and adjusts The body recycles iron, and adjusts absorption and excretion as neededabsorption and excretion as needed
• In adult men, the breakdown of older RBCs In adult men, the breakdown of older RBCs supplies ~95% of the iron required to supplies ~95% of the iron required to produce new RBCsproduce new RBCs
• Adults lose ~1mg per day in the feces, Adults lose ~1mg per day in the feces, intestinal cells, and skinintestinal cells, and skin
• Women require additional iron to Women require additional iron to compensate for blood loss during compensate for blood loss during menstruationmenstruation
SOURCES of IRONSOURCES of IRON
• Good sources include beef, clams, oysters, Good sources include beef, clams, oysters, tofu, legumes, and livertofu, legumes, and liver
• Fortified cereals provide iron in the Fortified cereals provide iron in the American diet American diet
• Foods cooked in iron cookware take up iron Foods cooked in iron cookware take up iron salts. The more acidic the food, and the salts. The more acidic the food, and the longer it is cooked, the higher the iron longer it is cooked, the higher the iron content. However, the absorption may be content. However, the absorption may be poorpoor
IRON DEFICIENCYIRON DEFICIENCY
• Stages of Iron Deficiency: depletion of iron Stages of Iron Deficiency: depletion of iron stores – depletion of functional iron – iron stores – depletion of functional iron – iron deficiency anemiadeficiency anemia
• Iron-deficiency anemia is characterized by Iron-deficiency anemia is characterized by microcytic, hypochromic RBCmicrocytic, hypochromic RBC
IRON TOXICITYIRON TOXICITY• Iron poisoning is the leading cause of accidental Iron poisoning is the leading cause of accidental
death in small childrendeath in small children• In a condition called Hemochromatosis, a genetic In a condition called Hemochromatosis, a genetic
defect causes excessive iron absorption. Iron defect causes excessive iron absorption. Iron builds up in many parts of the body, leading to builds up in many parts of the body, leading to severe organ damage and even deathsevere organ damage and even death
• An intake in excess of the RDA by adult men and An intake in excess of the RDA by adult men and postmenopausal women may increase risk for postmenopausal women may increase risk for heart disease and cancerheart disease and cancer
• Excessive iron helps to generate large amounts of Excessive iron helps to generate large amounts of free radicals that attack cellular moleculesfree radicals that attack cellular molecules
CALCIUM: FunctionsCALCIUM: Functions
• Bone Structure: as bones begin to form, Bone Structure: as bones begin to form, calcium salts form crystals called calcium salts form crystals called hydroxyapatite, on a matrix of collagen. hydroxyapatite, on a matrix of collagen. During mineralization, as the crystals become During mineralization, as the crystals become denser, they give strength and rigidity to denser, they give strength and rigidity to maturing bonesmaturing bones
• The calcium in bones serves as a calcium The calcium in bones serves as a calcium “bank”“bank”
• Peak bone mass occurs at ~ 30 years of agePeak bone mass occurs at ~ 30 years of age
CALCIUM: FunctionsCALCIUM: Functions
• Nerve functionNerve function• Blood clottingBlood clotting• Muscle contractionMuscle contraction• Cellular metabolismCellular metabolism
CALCIUM: SourcesCALCIUM: Sources• Dairy products, blackstrap molasses, canned fish with Dairy products, blackstrap molasses, canned fish with
bones, almonds, sesame seeds, some dark green leafy bones, almonds, sesame seeds, some dark green leafy vegetables vegetables
• Depends on bioavailability: Depends on bioavailability: • >50% absorbed – kale, mustard greens, bok choy, >50% absorbed – kale, mustard greens, bok choy,
turnip greens, broccoli, calcium-fortified foods and turnip greens, broccoli, calcium-fortified foods and beveragesbeverages
• ~30% absorbed – dairy foods, calcium set tofu~30% absorbed – dairy foods, calcium set tofu• ~20% absorbed – almonds, sesame seeds, pinto beans~20% absorbed – almonds, sesame seeds, pinto beans• <5% absorbed – swiss chard, spinach, rhubarb<5% absorbed – swiss chard, spinach, rhubarb
CALCIUM ABSORPTIONCALCIUM ABSORPTION
• The body normally absorbs 25 to 75% of The body normally absorbs 25 to 75% of dietary calcium, depending upon Vitamin dietary calcium, depending upon Vitamin D, the body’s need, and calcium intakeD, the body’s need, and calcium intake
• Calcium absorption is highest during Calcium absorption is highest during pregnancy and infancy, lowest in old agepregnancy and infancy, lowest in old age
• Phytates, high levels of phosphorus and Phytates, high levels of phosphorus and magnesium, and low estrogen levels can magnesium, and low estrogen levels can decrease absorptiondecrease absorption
OSTEOPOROSISOSTEOPOROSIS
• Osteoporosis is one of the most prevalent Osteoporosis is one of the most prevalent disease of aging, affecting more than 25 disease of aging, affecting more than 25 million people in the US – most of them million people in the US – most of them womenwomen
• The disease occurs when the bone mineral The disease occurs when the bone mineral density becomes so low that the skeleton is density becomes so low that the skeleton is unable to sustain ordinary strains, a unable to sustain ordinary strains, a condition marked by the occurrence of condition marked by the occurrence of fractures fractures
BONE BUIDLING NUTRIENTSBONE BUIDLING NUTRIENTS
• Calcium, phosphorus, fluoride, magnesium, Calcium, phosphorus, fluoride, magnesium, potassium, Vitamin A, Vitamin D, Vitamin Kpotassium, Vitamin A, Vitamin D, Vitamin K
• Possibly iron, copper, zinc, manganese, and Possibly iron, copper, zinc, manganese, and boron - function in bone metabolism, but boron - function in bone metabolism, but their roles in preventing bone loss are not well their roles in preventing bone loss are not well establishedestablished
OSTEOPOROSISOSTEOPOROSIS
Dietary FactorsDietary Factors• Excessive dietary fiber may interfere with calcium Excessive dietary fiber may interfere with calcium
absorptionabsorption• Excessive animal protein consumption may lead to Excessive animal protein consumption may lead to
increased urinary calcium excretionincreased urinary calcium excretion• High sodium intakes, especially in association with High sodium intakes, especially in association with
low calcium intakes, can result in increased urinary low calcium intakes, can result in increased urinary calcium excretioncalcium excretion
• Caffeine can reduce calcium absorption and increase Caffeine can reduce calcium absorption and increase excretion ratesexcretion rates
• High phosphorus intake, in association with low High phosphorus intake, in association with low calcium intake may increase bone losscalcium intake may increase bone loss
PREVENTION of PREVENTION of OSTEOPOROSISOSTEOPOROSIS
• Increase intake of bone-building nutrientsIncrease intake of bone-building nutrients• Reduce consumption of alcohol, tobacco, Reduce consumption of alcohol, tobacco,
caffeine, sodium, and animal proteincaffeine, sodium, and animal protein• Engage in regular weight-bearing exerciseEngage in regular weight-bearing exercise
OSTEOPOROSISOSTEOPOROSIS
Risk Factors:Risk Factors:• Aging, female sex, limited intake of bone Aging, female sex, limited intake of bone
building nutrients, excessive consumption building nutrients, excessive consumption of potentially damaging substances of potentially damaging substances (alcohol, tobacco), sedentary lifestyle, lack (alcohol, tobacco), sedentary lifestyle, lack of sunlight, decreased estrogen levels, of sunlight, decreased estrogen levels, genetics, and racegenetics, and race
REGULATION of BLOOD REGULATION of BLOOD CALCIUMCALCIUM
• Vitamin DVitamin D• Parathyroid HormoneParathyroid Hormone• CalcitoninCalcitonin• Figure 11.19Figure 11.19
CALCIUM ABSORPTIONCALCIUM ABSORPTION
• The body normally absorbs 25 to 75% of The body normally absorbs 25 to 75% of dietary calcium, depending upon Vitamin dietary calcium, depending upon Vitamin D, the body’s need, and calcium intakeD, the body’s need, and calcium intake
• Calcium absorption is highest during Calcium absorption is highest during pregnancy and infancy, lowest in old agepregnancy and infancy, lowest in old age
• Phytates, high levels of phosphorus and Phytates, high levels of phosphorus and magnesium, and low estrogen levels can magnesium, and low estrogen levels can decrease absorptiondecrease absorption