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Chapter 12 – Water and the Major Minerals
Learning Objectives
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List the uses of water in the body.
Describe water balance and the sources of water for the body.
Describe the effects of inadequate and excessive intakes of water.
Identify the daily Adequate Intake for total water.
Explain the hormonal regulation of body water to maintain blood volume and blood pressure.
Explain the role of electrolytes in maintaining water and acid-base balance.
Describe the role of the kidneys in maintaining homeostasis.
Describe minerals, and classify them as major or trace minerals.
Identify the role of sodium in the body and the effects of excessive or inadequate sodium.
Identify the food sources of sodium and the daily Tolerable Upper Intake Level.
Identify the role of chloride in the body.
Describe the role of potassium in the body and effects of excessive and inadequate intake.
Identify food sources of potassium.
Describe the role of calcium in the body and the factors that enhance or limit its absorption from the diet.
Identify food sources of calcium and the recommended dietary intake of calcium.
Describe the effects of calcium deficiency.
Identify the role or phosphorus in the body, recommended intake, and food sources.
Identify the role of magnesium in the body, food sources of magnesium, and the effects of inadequate intake.
Identify the role of sulfate of the body.
Discuss osteoporosis, including bone development and disintegration and the two major types of osteoporosis.
Identify the risk factors for the development of osteoporosis and the roles of physical activity and calcium intake.
Discuss the selection of a calcium supplement.
Lecture Presentation Outline
I.
Water and the Body Fluids
The main role of water is to maintain an appropriate water balance to support vital functions. To maintain water homeostasis,
intake from liquids, foods, and metabolism must equal losses from the kidneys, skin, lungs, and feces.
A. Water’s roles in the body
1. Carries nutrients and waste products.
2. Maintains the structure of large molecules.
3. Participates in metabolic reactions.
4. Solvent for minerals, vitamins, amino acids, glucose, and others.
5. Lubricant and cushion around joints, inside the eyes, the spinal cord, and in amniotic fluid during pregnancy.
6. Regulation of body temperature.
7. Maintains blood volume.
B. Water Balance and Recommended Intakes
1. Intracellular fluid (inside the cells) makes up about two-thirds of the body’s water.
2. Extracellular fluid (outside the cells) has two components—the interstitial fluid and plasma.
3. Water Intake
a. Thirst is a conscious desire to drink and is regulated by the mouth, hypothalamus, and nerves.
b. Dehydration occurs when water output exceeds input due to an inadequate intake or excessive losses.
1. Symptoms of a 1%-2% loss of body weight include thirst, fatigue, weakness, vague discomfort, and loss of
appetite.
2. Symptoms of a 3%-4% loss of body weight include impaired physical performance, dry mouth, reduction in
urine, flushed skin, impatience, and apathy.
3. Symptoms of a 5%-6% loss of body weight include difficulty in concentrating, headache, irritability,
sleepiness, impaired temperature regulation, and increased respiratory rate.
4. Symptoms of a 7%-10% loss of body weight include dizziness, spastic muscles, loss of balance, delirium,
exhaustion, and collapse.
c.
Water intoxication is excessive water contents in all body fluid compartments leading to a dangerous condition
known as hyponatremia.
4. Water sources include water, other beverages, fruit, vegetables, meat, cheese, and the byproduct of metabolism. An
intake of 1450 to 2800 milliliters of water is usually represented by:
a. Liquids – 550 to 1500 mL.
b. Foods – 700 to 1000 mL.
c. Metabolic water – 200 to 300 mL.
5. Water losses occur through urine output, water vapor from the lungs, sweating, and feces. An output of 1450 to 2800
milliliters of water is usually represented by:
a. Kidneys – 500 to 1400 mL.
b. Skin – 450 to 900 mL.
c. Lungs – 350 mL.
d. GI tract – 150 mL.
6. Water Recommendations
a. 1.0 to 1.5 mL/kcal expended for adults (approximately 2-3 liters for a 2,000 kcalorie expenditure.
b. 1.5 mL/kcal expended for infants and athletes.
c. ½ cup per 100 kcal expended.
d. Adequate Intake for males is 3.7 L/day.
e. Adequate Intake for females is 2.7 L/day.
f. Both caffeine and alcohol can have a diuretic effect.
7. Health Effects of Water
a. Meeting fluid needs.
b. Protects the bladder, prostrate, and breast against cancer.
c. Protects against kidney stones.
8. Kinds of water
a. Hard water
1. Water with high calcium and magnesium content.
2. Leaves residues.
3. May benefit hypertension and heart disease.
b. Soft water
1. Water with high sodium and potassium content.
2. May aggravate hypertension and heart disease.
3. Dissolves contaminant minerals in pipes.
4. Practical advantages.
c. Other types of water:
1. Artesian water – water drawn from a well that taps a confined aquifer in which the water in under pressure.
2. Bottled water – drinking water sold in bottles
3. Carbonated water – water that contains carbon dioxide gas, either natural or added.
4. Distilled water – free of dissolved minerals.
5. Filtered water – water treated by filtration with lead, arsenic, and some microorganisms removed.
6. Mineral water – water from a spring or well that contains at least 250 parts per million of minerals.
7. Natural water – water from a spring or well that is certified to be safe and sanitary.
8. Public water – water from a city or county water system that has been treated and disinfected.
9. Purified water – water that has been treated to remove dissolved solids.
10. Spring water – water originating from an underground spring or well.
11. Well water – water drawn from ground water by tapping into an aquifer.
C. Blood Volume and Blood Pressure – Fluids are essential to the regulation of blood volume and blood pressure.
1. ADH and water retention
a. Antidiuretic hormone (ADH) is released from the pituitary gland and causes kidneys to reabsorb water, thus
preventing losses.
b. Vasopressin is another name for ADH.
2. Renin
a. Kidneys release renin to reabsorb sodium.
b. Helps to restore blood pressure and blood volume.
3. Angiotensin
a. With the assistance of renin, angiotensinogen is hydrolyzed to angiotensin I.
b. An enzyme converts angiotensin I to angiotensin II.
c. Angiotensin II is a vasoconstrictor that raises blood pressure by narrowing blood vessels.
4. Aldosterone
a. Angiotensin II mediates the release of aldosterone from the adrenal glands.
b. Kidneys retain sodium in order to retain water.
D. Fluid and Electrolyte Balance – Several minerals including sodium, chloride, potassium, calcium, phosphorus,
magnesium, and sulfur are involved in fluid balance.
1. Dissociation of Salt in Water
a. Dissociates into positive ions called cations and negative ions called anions.
b. Ions carry electrical current so they are called electrolytes.
c. Solutions are called electrolyte solutions.
d. Positive and negative charges inside and outside the cell must be balanced.
e. Milliequivalents is the concentration of electrolytes in a volume of solution.
2. Electrolytes Attract Water
a. Water molecules are neutral, polar.
b. Oxygen is negatively charged. Hydrogen is positively charged.
c. Enables body to move fluids.
3. Water Follows Electrolytes
a. Sodium and chloride are primarily outside the cell.
b. Potassium, magnesium, phosphate, and sulfur are primarily inside the cell.
c. Osmosis is the movement of water across the cell membrane toward the more concentrated solutes.
d. Osmotic pressure is the amount of pressure needed to prevent the movement of water across a cell membrane.
4. Proteins Regulate Flow of Fluids and Ions
a. Proteins attract water and regulate fluid balance.
b. Transport proteins regulate the passage of positive ions.
c. Negative ions follow.
d. Water flows toward the more concentrated solution.
e. The sodium-potassium pump uses ATP to exchange minerals across the cell membrane.
5. Regulation of Fluid and Electrolyte Balance
a. Digestive juices of GI tract contain minerals and these are reabsorbed as needed.
b. Kidneys maintain fluid balance using ADH.
c. Kidneys maintain electrolyte balance using aldosterone.
E. Fluid and Electrolyte Imbalance – Medications and medical conditions may interfere with the body’s ability to regulate the
fluid and electrolyte balance.
1. Different Solutes Lost by Different Routes
a. Vomiting or diarrhea causes sodium losses.
b. Kidneys may lose too much potassium if there is adrenal hypersecretion of aldosterone.
c. Uncontrolled diabetics may lose glucose and fluid via the kidneys.
2. Replacing Lost Fluids and Electrolytes
a. Drink plain cool water and eat regular foods for temporary small losses.
b. Greater losses require oral rehydration therapy (ORT) (½ L boiling water, 4 tsp sugar, and ½ tsp salt). Cool
before giving.
F. Acid-Base Balance – The body must maintain an appropriate balance between acids and bases to sustain life. Acidity in
measured by the pH value, the concentration of hydrogen atoms.
1. Regulation by the Buffers
a. First line of defense.
b. Carbonic acid and bicarbonate can neutralize acids and bases.
c. Carbon dioxide forms carbonic acid in the blood that dissociates to hydrogen ions and bicarbonate ions.
2. Regulation in the Lungs
a. Respiration speeds up and slows down as needed to restore homeostasis.
3. Regulation in the Kidneys
a. Selects which ions to retain and which to excrete.
b. The urine’s acidity level fluctuates to keep the body’s total acid content balanced.
II. The Minerals—An Overview
Major minerals are found in large quantities in the body, while trace minerals are found in small quantities. Minerals receive
special handling in the body. They may bind with other substances and interact with other minerals, thus affecting absorption.
A. Inorganic Elements
1. Major minerals or macrominerals retain their chemical identity when exposed to heat, air, acid, or mixing.
2. Minerals can be lost when they leach into water.
B. The Body’s Handling of Minerals
1. Some behave like water-soluble vitamins.
2. Some behave like fat-soluble vitamins.
3. Excessive intake of minerals can be toxic.
C. Variable Bioavailability
1. Binders in food can combine chemically with minerals and prevent their absorption.
2. Phytates are found in legumes and grains.
3. Oxalates are found in spinach and rhubarb.
D. Nutrient Interactions
1. Sodium and calcium.
2. Phosphorus and magnesium.
3. Often caused by supplements.
E. Varied Roles
1. Sodium, potassium, and chloride function primarily in fluid balance.
2. Calcium, phosphorus, and magnesium function primarily in bone growth and health.
III. Sodium
Sodium is one of the primary electrolytes in the body and is responsible for maintaining fluid balance. Dietary
recommendations include a moderate intake of salt and sodium. Excesses may aggravate hypertension. Most of the sodium in
the diet is found in table salt and processed foods.
A. Sodium Roles in the Body
1. Maintains normal fluid and electrolyte and acid-base balance.
2. Assists in nerve impulse transmission and muscle contraction.
3. Filtered out of the blood by the kidneys.
B. Sodium Recommendations
1. Minimum adults: 500 mg/day
2. Adequate Intake
a. For those 19-50 years of age, 1,500 mg/day.
b. For those 51-70 years of age, 1,300 mg/day.
c. For those older than 70 years of age, 1,200 mg/day.
3. The upper intake level for adults is 2,300 mg/day.
4. Maximum % Daily Value on food labels is set at 2400 mg/day.
C. Sodium and Hypertension
1. Salt has a great impact on high blood pressure. Salt restriction does help to lower blood pressure.
2. Salt sensitivity is a term to describe individuals who respond to a high salt intake with high blood pressure.
3. Dietary Approaches to Stop Hypertension (DASH) is a diet plan that helps to lower blood pressure.
D. Sodium and Bone Loss (Osteoporosis)
1. High sodium intake is associated with calcium excretion.
E. Sodium in Foods
1. Large amounts in processed foods (approximately 75% of sodium in the diet).
2. Table salt (approximately 15% added sodium in the diet).
3. Sodium may be present in surprisingly high amounts if chloride is removed.
4. Moderate amounts in meats, milks, breads, and vegetables (approximately 10% of sodium in the diet).
F. Sodium Deficiency
1. Sodium and water must be replaced after vomiting, diarrhea, or heavy sweating.
2. Symptoms are muscle cramps, mental apathy, and loss of appetite.
3. Salt tablets without water induce dehydration.
4. Be careful of hyponatremia during ultra-endurance athletic activities.
G. Sodium Toxicity and Excessive Intakes
1.
2.
Edema and acute hypertension.
Prolonged high intake may contribute to hypertension.
IV. Chloride
Chloride in an essential nutrient that plays a role in fluid balance. It is associated with sodium and part of hydrochloric acid in
the stomach.
A. Chloride Roles in the Body
1. Maintains normal fluid and electrolyte balance.
2. Part of hydrochloric acid found in the stomach.
3. Necessary for proper digestion.
B. Chloride Recommendations and Intakes
1. Recommendations
a. Adequate Intake
1. For those 19-50 years of age, 2,300 mg/day.
2. For those 51-70 years of age, 2,000 mg/day.
3. For those older than 70 years of age, 1,800 mg/day.
b. Upper intake level is 3,600 mg/day.
2. Chloride intakes
a. Abundant in foods.
b. Abundant in processed foods.
C. Chloride Deficiency and Toxicity
1. Deficiency is rare.
2. Losses can occur with vomiting, diarrhea, or heavy sweating.
3. Dehydration due to water deficiency can concentrate chloride to high levels.
4. The toxicity symptom is vomiting.
V. Potassium
Potassium is another electrolyte associated with fluid balance. It is associated (inversely) with hypertension. It is found in fresh
foods—mostly fruits and vegetables.
A. Potassium Roles in the Body
1. Maintains normal fluid and electrolyte balance.
2. Facilitates many reactions.
3. Supports cell integrity.
4. Assists in nerve impulse transmission and muscle contractions.
5. Maintains the heartbeat.
B. Potassium Recommendations and Intakes
1. Adequate Intake – For all adults, 4,700 mg/day.
2. Fresh foods are rich sources.
3. Processed foods have less potassium.
C. Potassium and Hypertension
1. Low potassium intakes increase blood pressure.
2. High potassium intakes prevent and correct hypertension.
D. Potassium Deficiency
1. Symptoms include muscular weakness, paralysis, confusion, increased blood pressure, salt sensitivity, kidney stones,
and bone turnover.
2. Later signs include irregular heartbeats, muscle weakness, and glucose intolerance.
E. Potassium Toxicity
1. Results from supplements or overconsumption of potassium salts.
2. Can occur with certain diseases or treatments.
3. Symptoms include muscular weakness and vomiting.
4. If given into a vein, potassium can cause the heart to stop.
VI. Calcium
Most of calcium (99%) is found in the bones. The remaining calcium (1%) is found in the blood and has many functions. Bone
and blood calcium are kept in balance with a system of hormones and vitamin D. Blood calcium remains in balance at the
expense of bone calcium and at the risk of developing osteoporosis in later years.
A. Calcium Roles in the Body
1. Calcium in Bones
a. Hydroxyapatite are crystals of calcium and phosphorus.
b. Mineralization is the process whereby minerals crystallize on the collagen matrix of a growing bone, hardening
of the bone.
c. There is an ongoing process of remodeling constantly taking place.
2. Calcium in Body Fluids
a. Calmodulin is an inactive protein that becomes active when bound to calcium and serves as an interpreter for
hormone and nerve-mediated messages.
b. Ionized calcium has many functions.
3. Calcium and Disease Prevention
a. May protect against hypertension.
b. DASH diet that is rich in calcium, magnesium, and potassium.
c. May be protective relationship with blood cholesterol, diabetes, and colon cancer.
4. Calcium and Obesity
a. Maintaining healthy body weight.
b. Calcium from dairy foods has better results than calcium from supplements.
c. More research is needed.
5. Calcium Balance
a. Works with vitamin D.
b. Works with parathyroid hormone and calcitonin.
c. Calcium rigor develops when there are high blood calcium levels and causes the muscles to contract.
d. Calcium tetany develops when there are low blood calcium levels and causes uncontrolled muscle contractions.
e. Abnormalities are due to problems with hormone secretion or lack of vitamin D.
f. Bones get robbed of calcium before blood concentrations get low.
6. Calcium Absorption
a. Absorption rate for adults is 30% of calcium consumed.
b. Calcium-binding protein is needed for calcium absorption.
c. Factors that enhance absorption
1. Stomach acid.
2. Vitamin D.
3. Lactose.
4. Growth hormones.
d. Factors that inhibit absorption
1. Lack of stomach acid.
2. Vitamin D deficiency.
3. High phosphorus intake.
4. High-fiber diet.
5. Phytates in seeds, nuts, and grains.
6. Oxalates in beet greens, rhubarb, and spinach.
B. Calcium Recommendations and Sources
1. Calcium Recommendations
a. AI adolescents: 1300 mg/day.
b. AI adults: 1000 mg/day if 19-50 years of age.
c. AI adults: 1200 mg/day if greater than 50 years of age.
d. Upper level for adults: 2500 mg/day.
e. Peak bone mass is the bone’s fullest potential in size and density developed in the first three decades of life.
2. Calcium in Milk Products
a. Drink milk.
b. Eat yogurt and cheese.
c. Add dry milk during food preparation.
3. Calcium in Other Foods
a. Tofu, corn tortillas, some nuts, and seeds.
b. Mustard and turnip greens, broccoli, bok choy, kale, parsley, watercress, and seaweed (nori).
c. Legumes.
d. Oysters and small fish consumed with bones.
e. Mineral waters, calcium-fortified orange juice, fruit and vegetable juices, and high-calcium milk.
f. Calcium-fortified cereals and breads.
D. Calcium Deficiency
1. Osteoporosis is the disease where the bones become porous and fragile due to mineral losses.
2. No obvious symptoms of mineral loss in bones appear. It is silent.
3. Deficiency in children can present as stunted growth.
4. Toxicity symptoms include constipation, increased risk of urinary stone formation, kidney dysfunction, and
interference with the absorption of other minerals.
VII. Phosphorus
Most of the phosphorus is found in the bones and teeth. It is also important in energy metabolism, as part of phospholipids, and
as part of genetic materials.
A. Phosphorus Roles in the Body
1. Mineralization of bones and teeth.
2. Part of every cell.
3. Genetic material (DNA and RNA).
4. Part of phospholipids.
5. Energy transfer.
6. Buffer systems that maintain acid-base balance.
B. Phosphorus Recommendations and Intakes
1. RDA adults: 700 mg/day for ages 19-70 years.
2. Upper intake level for those 19-70 years of age is 4,000 mg/day.
3. Sources include all animal foods including meat, fish and poultry, milk, and eggs.
C. Phosphorus toxicity symptoms include the calcification of nonskeletal tissues, especially the kidneys.
VIII. Magnesium
Magnesium supports bone mineralization, and is involved in energy systems and in heart functioning. It is widespread in foods.
A. Magnesium Roles in the Body
1. Bone mineralization.
2. Building of protein.
3. Enzyme action.
4. Normal muscle contraction.
5. Nerve impulse transmission.
6. Maintenance of teeth by preventing dental caries.
7. Functioning of the immune system.
8. Blood clotting.
B. Magnesium Intakes
1. RDA adult men: 400 mg/day for 19-30 years of age.
2. RDA adult women: 310 mg/day for 19-30 years of age.
3. Upper level for adults: 350 mg nonfood magnesium/day.
4. Nuts and legumes, whole grains, dark green vegetables, seafood, chocolate, and cocoa.
5. Hard water and some mineral waters.
C. Magnesium Deficiency
1. Deficiencies are rare.
2. Symptoms
a. Weakness and confusion.
b. Convulsions in extreme deficiency.
c. Bizarre muscle movements of the eye and face.
d. Hallucinations.
e. Difficulties in swallowing.
f. Growth failure in children.
3. Develops from alcohol abuse, protein malnutrition, kidney disorders, and prolonged vomiting and diarrhea.
D. Magnesium and Hypertension
1. Protects against heart disease and hypertension.
2. Low magnesium restricts walls of arteries and capillaries.
E. Magnesium Toxicity
1. Symptoms from nonfood magnesium are diarrhea, alkalosis, and dehydration.
IX. Sulfate
Sulfate requirements are met by consuming a varied diet. It is found in essential nutrients including protein. There is no
recommended intake and there are no known deficiencies (apart from PEM).
X. Highlight: Osteoporosis and Calcium
Osteoporosis is one of the most prevalent diseases of aging. Strategies to reduce risks involve dietary calcium.
A. Bone Development and Disintegration
1. Cortical bone is the outer shell compartment of bone.
a. Creates the shell of long bones.
b. Creates the shell caps on the end of bones.
c. Releases calcium slower than trabecular bone.
d. Losses can begin in the 40s.
2. Trabecular bone is the inner lacy matrix compartment of bone.
a. Can be affected by hormones in the body signaling the release of calcium.
b. Provides a source for blood calcium when needed.
c. Losses can become significant in the 30s for men and women.
1. Results in type I osteoporosis.
2. Can result in spine and wrist fractures and loss of teeth.
3. Women are affected 6 times as often as men.
3. Losses of both trabecular and cortical bone result in type II osteoporosis.
a. Can result in compression fractures of the spine.
b. Hip fractures can develop.
c. Twice as common in women as in men.
4. The diagnosis of osteoporosis is performed using bone density tests.
5. Individual risk factors for osteoporosis are also considered.
B. Age and Bone Calcium
1. Maximizing Bone Mass
a. Children and adolescents need to consume enough calcium and vitamin D to create denser bones.
b. With a higher initial bone mass, the normal losses of bone density that occur with age will have less detrimental
effects.
2. Minimizing Bone Loss
a. Ensuring adequate intakes of vitamin D and calcium are consumed.
b. Hormonal changes can increase calcium losses.
C. Gender and Hormones
1. Men at lower risk than women.
2. Hormonal changes.
3. Rapid bone loss in nonmenstruating women.
4. Two main classes of medication can be used
a. Antiresorptive agents, which block bone resorption.
b. Anabolic agents, which stimulate bone formation.
5. Soy offers some protection.
D. Genetics and Ethnicity
1. Genes may play a role: risk for African Americans < for Caucasians < Asians or Central/South Americans.
2. Environment also – diet and calcium.
3. Physical activity, body weight, alcohol, and smoking have a role.
E. Physical Activity and Body Weight
1. Muscle strength and bone strength go together.
2. Heavy body weights and weight gains place a stress on bones and promote bone density.
Smoking and Alcohol
1. Smokers
a. Less dense bones.
b. Damage can be reversed when smoking stops.
2. Alcohol abuse
a. Enhances fluid excretion, thus increases calcium losses.
b. Upsets hormonal balance for healthy bones.
c. Slows bone formation.
d. Stimulates bone breakdown.
e. Increases risks of falling.
G. Dietary Calcium – the key to prevention
H. Other Nutrients
1. Adequate protein.
2. Adequate vitamin D.
3. Vitamin K protects against hip fractures.
4. Vitamin C may slow bone loss.
5. Magnesium and potassium help to maintain bone mineral density.
6. Vitamin A.
7. Omega-3 fatty acids.
8. Fruits and vegetables.
9. Reduce salt.
10. Phytochemicals such as lycopene.
I. A Perspective on Supplements
1. Calcium-rich foods are best.
2. Supplements may be needed when requirements are not met through foods.
3. Types of supplements
a. Antacids contain calcium carbonate.
b. Bone meal or powdered bone, oyster shell or dolomite are calcium supplements.
c. Contain lead??
d. Small doses are better absorbed.
e. Calcium generally absorbed equally well from Ca carbonate, citrate, or phosphate, but tablet disintegration is
important.
J. Some Closing Thoughts – Age, gender, and genetics are beyond control. There are effective strategies for prevention that
include adequate calcium and vitamin D intake, physical activity, moderation of alcohol, abstaining from cigarettes, and
supplementation if needed.
F.
Case Study
Michael is a 17-year-old high school football player who has recently been doing “two a day” practices in preparation for the
upcoming season. He is in good physical condition at 5 feet 10 inches and 165 pounds. He is attempting to gain weight, so he has
increased his intake of protein foods and estimates he eats approximately 3500 kcalories a day. One particularly hot afternoon,
Michael is sweating profusely and begins to feel weak and has a difficult time keeping up with his usual practice routines. Noticing
that his face is visibly flushed, his coach has him sit out of practice. Michael reports having eaten 2 peanut butter and jelly
sandwiches, potato chips, and a can of soda for lunch about 2 hours before practice. He had a breakfast burrito with eggs and cheese
for breakfast with a 12-ounce glass of orange juice.
1.
2.
3.
4.
5.
6.
7.
What signs of dehydration does Michael exhibit?
Based on these signs of dehydration, what percentage of body fluid would you estimate Michael has lost?
Along with water, what essential nutrients has Michael’s body most likely lost as result of his heavy sweating?
Using his reported caloric intake, estimate Michael’s fluid needs.
Besides fruit juice and soda, what foods and beverages would you encourage to meet Michael’s fluid requirements?
What food groups appear to be deficient in Michael’s usual diet? What essential nutrients are likely to be lacking as a result of
his limited diet?
Using information in this chapter and the simplified point system on page 405, estimate Michael’s calcium intake. Is this
adequate for his age? If not, what recommendations for increasing his calcium intake would you offer?
Answer Key:
1. Flushed skin, impaired physical performance, weakness.
2.
3 to 4 percent.
3.
Sodium and chloride.
4.
3500 kcalories x 1 to 1.5 mL fluid per calorie = 3.5 to 5.25 liters of fluid a day.
5.
Low-fat milk, vegetable juices, sports drinks, water.
6.
Vegetables, fruit, milk. Potassium and calcium are likely to be lacking.
7.
Estimated calcium intake: Cheese = 1 point or about 300 milligrams calcium; 4 slices bread = ½ point (see page 404), or a total
of about 450 milligrams of calcium. This is not adequate according to the recommended intake for adolescents to the age of 18,
who need 1300 milligrams a day. Recommend calcium-fortified orange juice; milk instead of soda at meals; additional cheese
or yogurt throughout the day.
Critical Thinking Questions
1.
Explain how homeostatic controls within the body are involved in regulating intracellular, intravascular, and other extracellular
fluids and the compounds dissolved in them.
Answer: Maintenance of Blood Volume and Blood Pressure: While this is not an activity that is performed by water or fluids
by themselves, the importance of fluids for blood volume and blood pressure should be obvious.
A complex system of renin, angiotensin, aldosterone, and ADH or antidiuretic hormone work with the kidneys, hypothalamus,
and pituitary gland to reabsorb sodium, constrict blood vessels to raise blood pressure, and cause excretion of potassium. This
excretion of potassium serves to cause retention of more sodium as well as water and the release of angiotensin II. Angiotensin
II stimulates the release of aldosterone from the adrenal glands, which in turn causes the pituitary gland to stimulate the release
of ADH or antidiuretic hormone. ADH stimulates the kidneys to reabsorb more water and signal the individual’s thirst
sensation, which will also add more water to the blood volume (assuming the person drinks). This complex system of enzymes
and hormones works together with the kidneys and the hypothalamic system to maintain blood volume and blood pressure.
Fluid and Electrolyte Balance: Maintaining homeostasis both inside and outside the cellular environments is critical to a healthy
living environment. Control of fluid movement into and out of the cells is achieved by the charges associated with minerals in
an electrolyte solution.
Electrolytes and water have an affinity for each other and tend to move across membranes by a process of osmosis or osmotic
pressure. The former occurs when water moves toward concentrated solutes, and the latter when water moves across a
membrane despite the pressure. Proteins also attract water and can help regulate the flow of fluids and ions accordingly.
Finally, it is the kidneys that regulate both water and electrolytes via ADH that is excreted via stimulation of the pituitary after
the release of aldosterone. Clearly, there are several levels of control for fluids and electrolytes in the body that work in concert
to achieve the final outcome.
Acid-Base Balance: Maintaining the pH within a very narrow range in the body is a delicate balancing act among the lungs, the
kidneys, and the blood. Metabolic and respiratory problems can result in acidosis or alkalosis and with the help of the kidneys
via the blood, pH can be restored.
Bicarbonate is an alkaline compound produced in the body. Its level is controlled by the kidneys in times of acidosis or
alkalosis in that the kidneys will either reabsorb more of the bicarbonate in the former situation or excrete more of the bicarb in
the latter situation.
Carbonic acid, an acid that is a product of CO2 and H2O, will lower pH if the level builds up significantly. The body prevents
this from happening by changing its respiratory rate to blow off more CO2 or reabsorbing more bicarbonate to stabilize the pH
range via the kidneys.
2.
Discuss the multiple roles of water in body fluids. Provide an example of what might happen if enough water is not available to
the body for each particular function, or give a clinical example of the particular function.
Answer:
 Carries nutrients throughout the body and waste products to be excreted out of the body
Example: The bodies of patients in renal failure cannot control fluid function; therefore, waste products build up in their
bodies and their ability to carry nutrients throughout their bodies is compromised.
3.

Maintains the structure of large molecules such as protein and glycogen
Example: As discussed in previous chapters, muscle retains lots of water to bathe the protein in a fluid environment and
allow for all of the metabolic reactions to occur. Muscle protein is also where glycogen is temporally stored and can readily
be released. Water is necessary for the reactions that occur during these high-energy reactions. Without water, none of
these very important reactions would take place. It is also important to note that water/fluid also maintains the structure of
cells and without that fluid structure, the cells would collapse.

Participates in metabolic reactions
Example: A fluid environment is needed for the metabolic reactions to occur. Many of the reactions require water in the
reaction itself. Without the water for the reaction, several metabolic reactions would fail to occur, causing death to the
body.

Serves as the solvent for minerals, vitamins, amino acids, glucose, and many other small molecules so that they can
participate in metabolic activities
Example: Same as above; these situations can be seen in a very dehydrated patient, and especially in the frail elderly. If the
dehydration progresses, one will note more tissue breakdown leading to system breakdown.

Acts as a lubricant and cushion around joints and inside the eyes, the spinal cord, and in pregnancy, the amniotic sac
surrounding the fetus in the womb
Example: In situations where athletes lose the lubricant between the joints, extreme pain results. Loss of amniotic fluid can
result in significant compromise of the fetus, leading to an emergency C-section.

Aids in the regulation of normal body temperature, as the evaporation of sweat from the skin removes excess heat from the
body
Example: Seen in heat exhaustion, where the body is unable to sweat to regulate body temperature, the process of sweating
to regulate body temperature is quite important.
Discuss the relationship among the members of the following groups of minerals: (1) sodium, chloride, and potassium; (2)
calcium, phosphorus, and magnesium. Within each group, discuss how the minerals are related and how the body will react to a
deficiency of the minerals vs. a toxicity.
Answer: (1) These minerals are often associated together, and all are involved in fluid and electrolyte balance. Sodium and
chloride often are attached to each other in foods as sodium chloride, which is found in salt. They become dissociated in the
body but are still important in fluid and electrolyte balance. Sodium is a positively charged mineral, chloride is a negatively
charged mineral, and both are found in the extracellular fluids. Sodium, given its abundance, is very important to the body for
nerve transmission and muscle contraction, both actions utilizing its charge in the neutral transmission process.
Potassium has a positive charge and is found within the cell. It is very important to cellular integrity and processes for nerve
impulse and muscle contraction and transmission within the cell.
The electrolytes work together but in different compartments, their charges balancing out. It is the positive and negative charges
that allow this to happen and give meaning to the term “opposites attract”!
(2) These three minerals are all involved in bone health in one way or another. Although many individuals think that only
calcium is involved in bone health, there are actually many minerals and other nutrients involved.
While calcium is one of the primary minerals involved in bone health, for example, phosphorus is also important through its
involvement in the mineralization of bone and also the entire process of calcium balance in the kidneys. The kidneys control
calcium and phosphorus reabsorption. Many studies have been done on the effects of soda consumption on calcium and
phosphorus, calcium consumption, and bone health. The findings conclude that those that drink lots of carbonated beverages do
not have any different bone density that those that do not drink carbonated drinks at all.
Many individuals do not consider magnesium a mineral that is involved in bone health. However, magnesium is very important
in the development of bone mineralization. This is because magnesium is involved in many of the metabolic reactions that are
involved in bone mineralization and bone health. So often, individuals downplay the role of dietetics in health care, yet diet is
crucial to the health and wellness of each of the patients we treat. Beyond that, there is much overlap in all the minerals and
how they assist each other.
4.
How would you determine a patient’s fluid balance?
Answer: Your text outlined the input and output method or the I & O which is a good means of determining a patient’s fluid
status or balance. To do this the dietitian or nursing assistant must determine all fluids going into the patient and all those that
are excreted from the patient.
With regard to input, the individual measuring input must account for all liquids that the patient consumes, including liquids
consumed taking medications. Liquids that are contained in foods must be accounted for as well as water released through
metabolic processes. There are books and charts that can be used for fluids in foods and equations that are used for fluids that
result from metabolic processes. Also to keep in mind that input includes IV fluids, NG, or other such fluids and parenteral
foods.
Output is measured by urine, fecal matter, and sweat and lung respirations. Urine is rather easy to measure as are feces. Sweat
and respirations must be estimated for the individual based on weight. Also, keep in mind that vomiting will be another output
that must be measured.
All input and output measurements are important to the total account of the patient’s fluid balance. Overlooking one
measurement can set the equations off and result in the RD trying to rebalance fluids unnecessarily.
5.
Bone health is influenced at a young age. What can college students do to maintain excellent bone health now and into their
older adult years of life?
Answer: Bone health is best influenced in the years of childhood and through the teen years. In the years between ages 8 and
12, the young child is accruing approximately 50% of their adult bone. Obviously, this is a critical period to influence bone
growth as well as enhance what is already there.
Many young children have some advantages in that they love pizza, smoothies, and yogurt-infused treats. For those that don’t,
it is a challenge for their parents. Making sure that the growing teenager consumes enough calcium-rich foods can be tough but
not impossible. Moreover, strong bones are key to a strong future.
During the college years, food habits are continually challenged as are sleep habits. The young adult should try to remember
that food habits now influence one’s body later (though this is often the last thing on their minds). Maintain a calcium-rich diet
by eating plenty of dairy products (and remember the evidence that calcium-rich milk can help in weight loss efforts). Exercise,
especially using weight-bearing sports, and receive adequate sleep. While sleep alone will not improve bone mass, stress does
release many caustic chemicals that can change your body’s metabolism and your eating habits to the disadvantage of your
bones. While no one can avoid stress, long-term stress is not good for the body.
Foods and beverages that should be consumed in moderation or not at all include soda and other caffeine-containing beverage;
soda because of the phosphorus, and caffeine because of the potential issues with calcium absorption. Phytates in foods like
spinach also tend to bind with calcium; therefore, trying to eat calcium-rich meals separately from spinach salads is a good idea.
Have fun with food and do not make it an enemy. It nourishes your body and mind so that you will be a better student and a
healthier older adult.