Week 13

Lecture | Study Guide |

Major Assignments

Lecture

Chapter 14 - Water and the Major Minerals
(This is listed for Wk 14 on the syllabus.)

In A Nutshell:

	Water acts as a solvent, provides the medium for transportation, participates in chemical reactions, provides lubrication and shock protection, and aids in temperature regulation in the human body.
	Water makes up about 60 percent of the body's weight. A change in the body's water content can bring a change in body weight.
	Water losses from the body necessitate intake equal to output to maintain balance. The brain regulates water intake; the brain and kidneys regulate water excretion. Dehydration can have serious consequences.
	Many factors influence a person's need for water. The water of beverages and foods helps meet water needs, as does the water formed during cellular breakdown of energy nutrients.
	Hard water is high in calcium and magnesium. Soft water is high in sodium, and it dissolves cadmium and lead from pipes.
	Electrolytes help keep fluids in their proper compartments and buffer these fluids, permitting all life processes to take place.
	Calcium makes up bone and tooth structure and plays roles in nerve transmission, muscle contraction, and blood clotting. Calcium absorption rises when there is a dietary deficiency or an increased need such as during growth.
	Most of the phosphorus in the body is in the bones and teeth. Phosphorus helps maintain acid-base balance, is part of the genetic material in cells, assists in energy metabolism, and forms part of cell membranes. Under normal circumstances, deficiencies of phosphorus are unknown.
	Sodium is the main positively charged ion outside the body's cells. Sodium attracts water. Thus, too much sodium (or salt) may aggravate hypertension. Diets rarely lack sodium.
	Potassium, the major ion inside cells, is important in many metabolic functions. Fresh foods are the best sources of potassium. Diuretics can deplete the body's potassium and so can be dangerous; potassium excess can also be dangerous.
	Chloride is the body's major negative ion; it is responsible for stomach acidity and assists in maintaining proper body chemistry.
	Sulfur plays important roles in body proteins.
	Iodine is part of the hormone thyroxine, which influences energy metabolism. The deficiency diseases are goiter and cretinism. Iodine occurs naturally in seafood and in foods grown on land that was once covered by oceans; it is an additive in milk and bakery products. Large amounts are poisonous.
	Most iron in the body is contained in hemoglobin and myoglobin or occurs as part of enzymes in the energy-yielding pathways. Iron-deficiency anemia is a problem worldwide; too much iron is toxic. Iron is lost through menstruation and other bleeding; reduced absorption and the shedding of intestinal cells protect against overload. For maximum iron absorption, use meat, other iron sources, and vitamin C together.
	Zinc assists enzymes in all cells. Deficiencies in children cause growth retardation with sexual immaturity. Zinc supplements can reach toxic doses, but zinc in foods is non-toxic. Animal foods are the best sources.
	Selenium works with an enzyme system to protect body compounds from oxidation. A deficiency induces a disease of the heart. Deficiencies are rare in developed countries, but toxicities occur from overuse of supplements.
	Fluoride stabilizes bones and makes teeth resistant to decay. Excess fluoride discolors teeth; large doses are toxic.
	Chromium works with the hormone insulin to control blood glucose concentrations. Chromium is present in a variety of unrefined foods.
	Copper is needed to form hemoglobin and collagen and assists in many other body processes. Copper deficiency is rare.
	Many different trace elements play important roles in the body. All of the trace minerals are toxic in excess.
	Hypertension is silent, progressively worsens atherosclerosis, and makes heart attacks and strokes likely. All adults should know their blood pressure.
	Atherosclerosis, obesity, insulin resistance, age, family background, and race contribute to hypertension risks.
	For most people, a healthy body weight, regular physical activity, moderation for those who use alcohol, and a diet high in fruits, vegetables, fish and low-fat diary products and low in fat work together to keep blood pressure normal. For some, salt restriction is also required.

Water is an essential nutrient that constitutes about 60% of the adult body weight. It is consumed in beverages and food, and a small amount is produced by metabolism.

Body water is distributed between intracellular and extra-cellular compartments. The amount in each compartment depends largely on the concentration of solutes. Because water will diffuse by osmosis from a compartment with a lower concentration of solutes to one with a higher concentration, the body regulates the distribution of water by adjusting the concentration of electrolytes and other solutes in each compartment.

Fluid intake is stimulated by the sensation of thirst, which occurs in response to a decrease in body water. Water is lost from the body in urine and feces and through evaporation from the skin and lungs. the kidney is the primary regulator of water output. If water intake is low, antidiuretic hormone (ADH) will cause the kidney to conserve water. If water intake is high, more water will be excreted in the urine. The amount of water required by the body, about 1 ml per kcal of intake, may vary depending on environmental conditions, and activity level.

The polar structure of the water molecule allows it to function as a solvent for the molecules and chemical reactions involved in metabolism. Water helps to transport other nutrients and waste products within the body and to excrete wastes from the body. It helps to protect the body, regulate body temperature, and lubricate areas such as the eyes and the joints. Water is also involved in the regulation of acid-base balance.

Dehydration can occur if water intake is too low or output is excessive. Mild dehydration can cause headache, fatigue, loss of appetite, dry eyes and mouth, and dark-colored urine. Severe dehydration can be fatal. Many Americans do not consume enough fluid.

The minerals sodium, chloride, and potassium are electrolytes that are important in the maintenance of fluid balance. The North American diet is abundant in sodium and chloride from processed foods and table salt but generally low in potassium, which is high in unprocessed foods such as fruits and vegetables.

Electrolyte and fluid homeostasis is regulated primarily by the kidneys. A decrease in blood pressure or blood volume signals the release of the enzyme renin, which helps form angiotensin II. Angiotensin II causes blood vessels to constrict and the hormone aldosterone to be released. Aldosterone causes the kidneys to reabsorb sodium and hence water, thereby increasing blood volume. Failure of these regulatory mechanisms may be a cause of hypertension.

Public health guidelines recommend consuming no more than 2400 mg of sodium per day and at least 3500 mg of potassium per day in order to promote a healthy blood pressure.

Hypertension, or high blood pressure, is common in the United States. A diet high in sodium increases blood pressure in some if not all individuals. Other nutrients, including potassium , magnesium, and calcium, also affect blood pressure.

To reduce the risk of hypertension, public health recommendations suggest a low to moderate intake of salt and sodium. The adoption of the DASH diet - a dietary pattern high in fruits, vegetables, low-fat dairy products, whole grains, and lean meat, fish, and poultry - is also recommended. This diet is rich in potassium, magnesium, calcium, and fiber, and low in fat, saturated fat, and cholesterol.

Minerals are elements needed by the body to regulate chemical reactions and provide structure. They come from plant and animal sources, and their bioavailability is affected by interactions with other minerals, vitamins, and other dietary components such as fiber, phytates, oxylates, and tannins. For some minerals, bioavailability is affected by body need.

Most of the calcium in the body is in bone as a component of hydroxyapatite. Calcium not found in bone is essential for nerve transmission, muscle contraction, blood clotting, and blood pressure regulation. Blood levels of calcium are regulated by parathyroid hormone and calcitonin. Parathyroid hormone stimulates the release of calcium from bone, decreases calcium excretion by the kidney, and activates vitamin D to increase the amount of calcium absorbed from the GI tract and released from bone. Calcitonin blocks calcium release from bone.

Bone is a living tissue that is constantly being broken down and reformed in a process known as bone remodeling. Early in life, bone formation occurs more rapidly than bone breakdown to allow bone growth and an increase in bone mass. Peak bone mass usually occurs in young adulthood. With age, bone breakdown begins to outpace formation, causing a decrease in bone mass; this is accelerated in women at menopause.

The AI for calcium ranges from 1000 to 1200 mg per day for adults and is 1300 mg per day in adolescents. Sources of calcium in the American diet include dairy products, fish consumed with bones, legumes, and leafy green vegetables.

Osteoporosis is a condition in which loss of bone mass increases the risk of bone fractures. The risk of osteoporosis is related to the level of peak bone mass achieved and the rate of bone loss. These are affected by genetics as well as lifestyle factors such as diet and exercise. The best treatment for osteoporosis is prevention. An adequate diet with plenty of calcium and regular exercise help increase bone mass during childhood and adolescence and decrease bone loss in adulthood. Once the disease occurs, treatment may include calcium and vitamin D supplements, exercise, or other medications.

Phosphorus plays a structural role in bones and teeth. Phosphorus is also part of a buffer system that helps prevent changes in pH and is an essential component of phospholipids, ATP, and DNA. Good sources of phosphorus include dairy products, meats, and grains. The RDA for adults is 700 mg per day.

Magnesium is important for bone health and it is needed as a cofactor for numerous reactions throughout the body. In reactions involved in energy production it acts as an enzyme activator and stabilizer of ATP; it is essential for nerve and muscle conductivity. Homeostasis is regulated by the kidney. Deficiency is rare, and the best dietary sources are whole grains, nuts, seeds, and green vegetables.

Sulfur enters the diet as the amino acids methionine and cysteine (needed to synthesize proteins and glutathione). Sulfur is also part of a buffer system that regulates acid-base balance. A dietary deficiency is unknown in the absence of protein malnutrition.

Study Guide

The following Study Guide exercises are for your information and practice.
They are not to be submitted to the instructor.

Matching Exercise:
___ 1. hemoglobin
___ 2. osteoporosis
___ 3. fluid and electrolyte balance
___ 4. goiter
___ 5. phytates
___ 6. peak bone mass
___ 7. iron overload
___ 8. buffers
___ 9. tannins
___ 10. heme
___ 11. dehydration
___ 12. iron deficiency
___ 13. hydroxyapatite
___ 14. cretinism
___ 15. MFP factor
___ 16. acid-base balance
___ 17. myoglobin
___ 18. pica

a. compounds in tea (especially black tea),
   and coffee that bind iron
b. enlargement of the thyroid gland due to
    iodine deficiency
c. the oxygen-holding protein of the
    muscles
d. the highest attainable bone density for
    an individual
e. the oxygen-carrying protein of the blood
f. severe mental and physical retardation of
   an infant caused by the mother's iodine
   deficiency during her pregnancy
g. maintenance of the proper amounts and
    kinds of fluids and minerals in each
   compartment of the body
h. the condition of having depleted iron
    stores, which, at the extreme, causes
    iron-deficiency anemia
i. maintenance of the proper degree of
acidity in each of the body's fluids
j. a reduction of the bone mass of older
   persons in which the bones become
   porous and fragile
k. molecules that can help to keep the pH
   of a solution from changing by gathering
   or releasing Hydrogen ions
l. the chief crystal of bone, formed from
   calcium and phosphorus
m. loss of water
n. a craving for nonfood substances
o. the state of having more iron in the body
    than it needs or can handle; too much
    iron is toxic and can damage the liver
p. a factor (identity unknown) present in
    meat, fish, and poultry that enhances
    the absorption of nonheme iron present
    in the same foods or in other foods
    eaten at the same time
q. the iron-containing portion of the
    hemoglobin and myoglobin molecules
r. compounds present in plant foods
   (particularly whole grains) that bind iron
   and prevent its absorption

Modify the following recipe to make it lower in calories, fat, and sodium and to substitute unsaturated (monounsaturated and polyunsaturated) fat for saturated fat.

Chicken Pot Pie

Pastry
1 cup flour
1/4 tsp. salt
2 tbsp. water
1/3 cup lard

Filling
1/3 cup chopped potatoes
1/3 cup sliced carrots
1/3 cup canned green peas
1/4 cup chopped celery
1 tbsp. chopped onion
1/2 cup boiling water
1/4 cup butter
1/4 cup flour
1/2 tsp salt
1/8 tsp pepper
1/8 tsp poultry seasoning
1 1/3 cup chicken broth
2/3 cup cream
1 1/2 cup diced, cooked chicken

Modifications: __________________________________________________________

______________________________________________________________________

Complete the following chart which identifies the names, chief functions, deficiency disease names, and major food sources of some of the major and trace minerals.

Name	Chief Functions	Deficiency Disease Name	Food Sources
Calcium	makes up bone and _____ structure normal muscle contraction nerve functioning blood _____ immune defenses	_______	milk small _____ with bones tofu greens legumes
Magnesium	_____ mineralization building of protein normal muscle contraction transmission of nerve _____ maintenance of _____		nuts _____ whole grains dark green _____ sea foods _____ cocoa
Sodium	maintains normal fluid balance maintains normal _____ balance		salt ____ foods ____ sauce
Iron	part of the protein _____ part of the protein _____ necessary for utilization of ____ in the body	_____	____ meats _____ poultry shellfish eggs legumes ____ fruits
Iodine	component of thyroid hormone _____	_____ _____	_____ _____ salt bread
Zinc	part of insulin and many ____ normal ____ development		____-containing foods

1. Which body compartment holds the largest amount of water? How much of the body's
water is found there?
2. What affects the amount of water required each day?
3. What are some of the factors to consider when selecting beverages?
4. How do sensible and insensible water losses differ?
5. What are the main signs of dehydration?
6. How are the major minerals differentiated from trace minerals?
7. What are 2 factors that can decrease bioavailability of a mineral?
8. What are 3 functions of minerals in the body?
9. Which foods contribute the most sodium to the diet?
10. How does the Adequate Intake (AI) of sodium compare with typical intakes in North
America?
11. How is excess sodium eliminated from the body?
12. What are the 3 main functions of sodium?
13. What are some strategies for decreasing sodium in the diet?
14. Which foods groups are generally good sources of potassium?
15. Where is most of the potassium in the body found?
16. What are 2 serious disorders linked to low potassium intakes?
17. Why is hyperkalemia (high blood potassium) rare?
18. What is the source of most dietary chloride?
19. What are the functions of chloride in the body?
20. How were chloride needs and Upper Level set?
21. What are the risk factors for developing high blood pressure?
22. Why is the periodic measurement of blood pressure important?
23. Why is hypertension a dangerous condition?
24. What lifestyle changes can help prevent and treat hypertension?
25. Which foods are the most bioavailable sources of calcium?
26. How do parathyroid hormone and vitamin D regulate serum calcium?
27. What are the functions of osteoblasts, osteocytes, and osteoclasts in bone?
28. Other than building bones and teeth, what are the functions of calcium in the body?
29. Which foods are high in phosphorus?
30. In addition to its structural roles for bones and teeth, what are 2 critical roles of phosphorus in the body?
31. What are some of the symptoms of phosphorus deficiency?
32. Which foods are good sources of magnesium?
33. What are the functions of magnesium in the diet?
34. What are the symptoms of magnesium deficiency?
35. which groups are most likely to be magnesium deficient?

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Becky Alejandre, Professor - Nutrition	Instructor's contact information Email: alejanb@arc.losrios.edu Phone: (916) 484-8145 FAX: (916) 484-8030	ARC Homepage	ARC Library
Office Location: Room #762 Health & Education Division (located between the tennis courts and the gym)		Office Hours: Mon. 8:00-10:00 a.m. Tues. 10:30-11:30 a.m. Wed. 10:30-11:30 a.m. (online) Thurs.10:30-11:30 a.m. Fri. 7:00-8:00 a.m. (online)

Becky Alejandre, Professor - Nutrition

Becky Alejandre,
Professor - Nutrition