Fluid Balance

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Minerals and Water

Chapter 8

Lecture Outline

Objectives for Chapter 8

Explain why water is important and the functions of water in the body.

Describe what water balance is and how to maintain it in the body.

Explain how much water you need daily and what the best sources are.

Explain what minerals are and why you need them.

Objectives for Chapter 8

Sodium

Potassium

Calcium

Phosphorus

Magnesium

Chloride

Sulfur

Iron

Copper

Zinc

Selenium

Fluoride

Chromium

Iodine

Manganese

Molybdenum

Identify the roles each of the following minerals plays in your body, food sources for each, and the consequences of consuming too much or too little of each.

Why Is Water So Important?

Water is the most abundant substance in body

Average healthy adult is about 60 percent water

Muscle tissue is 75 percent water, fat up to 20 percent

Can survive only a few days without water

Water is balanced among fluid compartments

Intracellular fluids: inside cells

Extracellular fluids: interstitial fluid between cells and fluid in the blood

Electrolytes: minerals that help maintain fluid balance

Intracellular and Extracellular Fluid

Your Body is Mostly Water

Figure 8.1

Water as Part of Body Fluids

Figure 8.2

Roles of Electrolytes in Water Balance

Why Is Water So Important?

Acts as universal solvent and transport medium

Medium for many chemical reactions in body

As part of blood, helps transport oxygen, nutrients, hormones to cells

As part of interstitial fluid, helps transport waste products away from cells for excretion

Helps maintain body temperature

Lubricant for joints, eyes; part of mucus and saliva

Protective cushion for brain, organs, fetus

Water Helps Regulate Your Body Temperature

Figure 8.3

What Is Water Balance and How Do You Maintain It?

Water balance: water consumed = water lost

You take in water through beverages and food

You lose water through your kidneys (as urine), large intestine, lungs, skin (as sweat)

Insensible water loss: through evaporation from skin and when you exhale

The Concept of Water Balance: Intake Equals Output

Figure 8.4

Water Balance

Losing Too Much Water Can Cause Dehydration

Dehydration can result from inadequate water intake or too much water loss from diarrhea, vomiting, high fever, or use of diuretics

Your thirst mechanism signals dehydration

Dry mouth due to increased electrolyte concentration in blood: less water available to make saliva

Blood volume decreases, sodium concentration increases in blood

Brain triggers thirst mechanism and secretion of antidiuretic hormone (ADH) to reduce urine output

Fluid inside cells moves into blood by osmosis

A Simple Demonstration of Osmosis

Figure 8.5

Losing Too Much Water Can Cause Dehydration

Other ways to tell if you're dehydrated:

Cornerstone method: measure body weight before and after exercise

Weight loss = water loss

Monitor urine color

Color darkens with concentration, indicating water loss

Urine Color Can Signal Dehydration

Figure 8.6

Consuming Too Much Water Can Cause Hyponatremia

Hyponatremia is a condition of too little sodium in the blood

For healthy individuals who consume a balanced diet, it is difficult to consume too much water

However, some individuals have experienced water toxicity

Examples: soldiers in training, endurance athletes

How Much Water Do You Need and What Are the Best Sources?

Daily water needs depend on physical activity, environmental factors, diet

Recommendations based on reported total water intake of healthy Americans

Men: 16 cups/day (about 13 cups of beverages)

Women: 12 cups/day (about 9 cups of beverages)

About 80 percent from beverages, 20 percent from foods

Physical activity increases needs

Discussion Questions

How many glasses of fluids should an adult woman drink each day? An adult man?

Where do we get 20 percent of the water we consume each day?

What scientific evidence exists for the belief that water helps the kidneys remove toxins from the body?

Drinking Water: How Much to Drink?

Water Content of Foods

Figure 8.8

BG: This will change (MyPlate).

The Best Way to Meet Your Daily Water Needs

Figure 8.9

Tap Water or Bottled Water: Is Bottled Better?

False assumption: bottled water is purer than tap water

Tap water is perfectly safe

Monitored by Environmental Protection Agency (EPA)

Provides fluoride, helps prevent dental caries

Bottled water is very popular

Most products conform to FDA requirements

May actually be tap water

High cost

Various "designer" waters on the market

Untable 8.1

Discussion Questions

What marketing and advertising methods have been employed to get people to purchase bottled water? What are the drawbacks of drinking bottled water? What are the advantages of drinking bottled water?

Discuss the environmental, financial, and health impacts of drinking bottled water versus tap water. Who benefits from the sale and purchase of bottled water?

If you were to create a public service announcement to advocate drinking tap water instead of bottled water, what claims would you make or what information would you include in your public service announcement?

Americans' Obsession with Bottled Water

Untable 8.2

Discussion Questions

What is enhanced water?

What are some false claims of enhanced water?

Are enhanced waters healthy beverages to consume?

Think Before You Drink: Can Water Boost Your Brain?

Practical Nutrition Tips Video: Enhanced Water

What Are Minerals and Why Do You Need Them?

Inorganic elements needed in relatively small amounts

Mineral absorption depends on bioavailability

Some minerals compete for absorption: too much of one can decrease absorption of another

Example: excess zinc can reduce copper absorption

Some substances bind minerals, making them unavailable for absorption

Example: oxalates in spinach bind calcium

What Are Minerals and Why Do You Need Them?

Major minerals (macrominerals): needed in amounts greater than 100 µg/day

Trace minerals (microminerals): needed in amounts less than 20 µg/day

You need major minerals in larger amounts

Sodium, chloride, potassium, magnesium, sulfur play key roles in fluid balance

Calcium, phosphorus, magnesium work together to strengthen bones and teeth

What Are Minerals and Why Do You Need Them?

Trace minerals are needed in small amounts

Play essential roles as important as major minerals

Chromium and iodine help certain hormones

Iron maintains healthy red blood cells

Fluoride protects teeth

Iron, zinc, copper, manganese, and molybdenum are cofactors that work with enzymes in critical chemical reactions

The Amounts of Different Minerals in Your Body

Figure 8.10

What Are Minerals and Why Do You Need Them?

Overconsumption of minerals can be toxic

Difference between recommended and excessive amount may be minimal

Example: magnesium, which can cause gastrointestinal problems

Foods alone rarely provide excessive amounts

Problems usually arise with supplements

Another good reason to eat a varied diet

Minerals Are Found Widely in MyPlate

Figure 8.11

Exploring Sodium

What are sodium and salt?

Sodium is an electrolyte (charged ion) in blood and in the fluid surrounding cells

About 90 percent of sodium consumed is in form of sodium chloride, table salt

Functions: chief role is regulation of fluid balance

Also transports substances such as amino acids across cell membranes

Exploring Sodium

Sodium balance in your body

Sodium level is maintained by the kidneys reducing or increasing sodium excretion as needed

Smaller amounts lost in stool and sweat

Daily needs: 1,500 µg/day for adults under 51

Food sources: 75 percent of sodium consumed by Americans comes from processed foods

About 10 percent occurs naturally in foods; another 5–10 percent added during cooking and at table

Recommended Intake of Sodium

Figure 8.12

Practical Nutrition Tips Video: Sodium Needs

Sodium Content of Selected Natural and Processed Foods

Figure 8.13

BG: Change

Exploring Sodium

Too much or too little:

UL for adults is set at 2,300 µg/day to reduce the risk of hypertension (high blood pressure)

Cut back on processed foods and salt added to foods to lower sodium intake

Sodium deficiency is rare in healthy individuals consuming a balanced diet

You and Your Blood Pressure

Blood pressure: a measure of force that blood exerts on the walls of arteries

Expressed as systolic pressure (when heart beats) over diastolic pressure (when heart is at rest between beats)

<120/80 mm Hg is normal

Systolic >120 or diastolic >80 = prehypertension

≥140/90 = hypertension

You and Your Blood Pressure

Hypertension is a silent killer

No symptoms – have blood pressure checked regularly

Contributes to atherosclerosis, heart enlarges and weakens

Damages arteries leading to brain and kidneys, increasing risk of stroke and kidney disease

To control hypertension:

Reduce weight, increase physical activity, eat a balanced diet

The DASH: (Dietary Approaches to Stop Hypertension)

Misc 8.8

Untable 8.3

Exploring Potassium

Important mineral with many functions:

Fluid balance: electrolyte inside cells

A blood buffer: helps keep blood pH and acid-base balance correct

Muscle contraction and nerve impulse conduction

Can help lower high blood pressure

Aids in bone health: helps increase bone density

Reduces kidney stones by helping to excrete citrate (binds with calcium to form kidney stones)

Kidney Stone

Figure 8.14

Exploring Potassium

Daily needs:

Adults: 4,700 mg/day

Adult females consume only about 2,400 µg/day and adult males only 3,170 µg/day, on average

Food sources:

Fruits and vegetables

Minimum of 4½ cups/day will help meet potassium needs

Dairy foods, nuts, legumes also good sources

Potassium Content in Selected Foods

Figure 8.15

Exploring Potassium

Too much or too little:

Too much from supplements or salt substitutes can cause hyperkalemia in some individuals

Can cause irregular heartbeats, damage heart, and be life-threatening

Too little can cause hypokalemia

Can cause muscle weakness, cramps, irregular heartbeats, and paralysis

Can occur as result of excessive vomiting and/or diarrhea, anorexia and/or bulimia eating disorders

Exploring Calcium

Most abundant mineral in body

More than 99 percent located in bones and teeth

Functions:

Helps build strong bones and teeth

Plays a role in muscles, nerves, and blood

May help lower high blood pressure

May fight colon cancer

May reduce risk of kidney stones (though supplements have opposite effect)

Calcium Metabolism

Exploring Calcium

Daily needs:

1,000 to 1,200 µg/day, depending on age

Food sources:

Milk, yogurt, cheese, broccoli, kale, canned salmon (with bones), tofu processed with calcium, calcium-fortified juices and cereals

Calcium Content in Selected Foods

Figure 8.16

Bioavailability of Calcium

Figure 8.17

Exploring Calcium

Too much or too little:

UL: 2,500 µg/day (ages 19–50); 2,000 µg (51+)

Too much calcium leads to hypercalcemia: impaired kidneys, calcium deposits in body

Too little can lead to less dense, weakened, brittle bones, and increased risk for osteoporosis

Calcium supplements:

Consume in doses of 500 mg or less

Some sources (oyster shell, bone meal, dolomite) may contain lead, other toxic metals

May be inadvisable if consuming enough in foods

BG: Hypercalcemia was removed from MS, but ED note there seems to indicate that it will be reinserted, with more explanatory text. For that reason I have not removed it here, but pages should be checked to confirm.

TD: Thanks for making note of that!

Healthy Bone (left) vs Weakened Bone (right)

Figure 8.18

Osteoporosis: Not Just Your Grandmother's Problem

Bones are living tissue, constantly changing

Peak bone mass occurs in early adulthood (20s)

Then slowly more bone is lost than added

As bones lose mass, they become more porous and prone to fractures, leading to osteoporosis

Bone mineral density (BMD) test measures bone density

Low score = osteopenia (low bone mass)

Very low score = osteoporosis

Weakened Bones Cause the Spine to Collapse over Time

Misc 8.14

Misc 8.15

Osteoporosis: Not Just Your Grandmother's Problem

Risk factors:

Gender (females at higher risk due to loss of estrogen after menopause)

Ethnicity (Caucasian and Asian-American at higher risk)

Age (over 30)

Body type (small-boned/petite women at higher risk)

Family history of fractures increases risk

Level of sex hormones (amenorrhea, menopause, or men with low levels of sex hormones)

Osteoporosis: Not Just Your Grandmother's Problem

Risk factors (continued):

Medications: glucocorticoids, antiseizure medications, aluminum-containing antacids, high amounts of thyroid replacement hormones

Smoking

Low physical activity: 30 minutes per day recommended

Alcohol (more than one drink for women, two for men)

Inadequate calcium and vitamin D (less than three cups/day of vitamin D-fortified milk or yogurt)

Exploring Phosphorus

Second most abundant mineral in body

85 percent in bones; rest in cells and fluids outside cells, including blood

Functions:

Needed for bones and teeth

Important component of cell membranes

Needed for energy metabolism and stores

Acts as a blood buffer

Part of DNA and RNA

Phosphorus in Phospholipids

Figure 8.19

Exploring Phosphorus

Daily needs:

Adults: 700 µg/day

Food sources:

Meat, fish, poultry, dairy

Abundant in diet

Too much or too little:

UL set at 4,000 µg/day for adults 19 to 50 to prevent hyperphosphatemia, which can lead to calcification of tissues; 3,000 µg for those aged 51 or older

Too little can result in muscle weakness, bone pain, rickets, confusion, death; would need to be in state of near starvation to experience deficiency

Phosphorus Content of Selected Foods

Figure 8.20

Exploring Magnesium

Another abundant mineral in body

About half in bones; most of rest inside cells

Functions:

Helps more than 300 enzymes, including energy metabolism

Used in synthesis of protein

Helps muscles and nerves function properly

Maintains healthy bones and regular heartbeat

May help lower high blood pressure and reduce risk of type 2 diabetes

Exploring Magnesium

Daily needs:

19 to 30 years: males, 400 µg/day; females, 310 µg/day

>30 years: males, 420 µg/day; females, 320 µg/day

Many Americans fall short (80 to 85 percent of needs)

Food sources:

Whole grains, vegetables, nuts, fruits; also milk, yogurt, meat, eggs

Too much or too little:

UL from supplements (not foods) = 350 µg/day to avoid diarrhea

Deficiencies are rare, but diuretics and some antibiotics can inhibit absorption

Magnesium Content of Selected Foods

Figure 8.21

Exploring Chloride

Chloride is part of hydrochloric acid in the stomach, which enhances protein digestion

Functions:

Sodium and chloride are major electrolytes outside cells and in blood to help maintain fluid balance

Acts as buffer to keep blood at normal pH

Daily needs: adults: 2,300 µg/day

Food sources: salt (NaCl) is main source

Too much or too little: deficiencies are rare

UL 3,600 µg/day to match sodium UL

Table Salt Is Composed of Sodium and Chloride

Figure 8.22

Exploring Sulfur

Component of other compounds in body, including the vitamins thiamin, biotin, pantothenic acid

Functions:

Helps give proteins 3-D shape as part of amino acids methionine, cystine, and cysteine

Sulfites used as food preservative

Food sources: meat, poultry, fish, eggs, legumes, dairy, fruits, vegetables

Too much or too little: no known toxicity or deficiency symptoms

Exploring Iron

Most abundant mineral on earth and main trace mineral in body

Two forms: heme and nonheme iron

Heme iron from animal sources is part of hemoglobin and myoglobin and easily absorbed

Nonheme iron in plant foods is not as easily absorbed, due to phytates and other substances

Body absorbs only 10 to 15 percent of iron consumed

Absorption increases if body stores are low

Not excreted in urine or stool; once absorbed, very little leaves body (95 percent recycled, reused)

Hemoglobin Contains Heme Iron

Figure 8.23

Exploring Iron

Functions:

Hemoglobin in red blood cells transports oxygen from lungs to tissues and picks up carbon dioxide waste from cells

Myoglobin transports and stores oxygen in muscle cells

Aids brain function by helping enzymes that make neurotransmitters

Daily needs:

Men and women >50: 8 µg/day

Women 19 to 50: 18 µg/day: higher due to iron lost during menstruation

Food sources:

Iron-enriched bread and grain products; heme iron in meats, fish, and poultry

Iron Content of Selected Foods

Figure 8.24

Exploring Iron

Too much or too little:

Too much iron from supplements can cause constipation, nausea, vomiting, diarrhea

In United States, a leading cause of accidental poisoning deaths in children under 6 years

Iron overload can damage heart, kidneys, liver, nervous system

Hemochromatosis, a genetic disorder, can cause iron overload

Iron deficiency: most common nutritional disorder in world

Iron-deficiency anemia occurs when iron stores are depleted and hemoglobin levels decrease

Normal and Anemic Blood Cells

Figure 8.25

Exploring Copper

Functions:

Part of many enzymes and proteins

Important for iron absorption and transfer, synthesis of hemoglobin and red blood cells

Helps generate energy in cells, synthesize melanin, link the proteins collagen and elastin together in connective tissues

Helps enzymes protect cells from free radicals

Role in blood clotting and maintaining healthy immune system

Exploring Copper

Daily needs:

Adults: 900 µg/day

Food sources:

Organ meats, seafood, nuts, seeds, bran cereals, whole-grain products, cocoa

Too much or too little:

UL: 10,000 µg/day

Excess can cause stomach cramps, nausea, diarrhea, vomiting, liver damage

Copper deficiency rare in United States

Copper Content of Selected Foods

Figure 8.26

Exploring Zinc

Involved in function of more than 100 enzymes

Functions:

DNA synthesis, growth, and development

Healthy immune system and wound healing

Taste acuity

Treatment for common cold

May reduce risk of age-related macular degeneration

Daily needs:

Men: 11 µg/day; women: 8 µg/day

Vegetarians may need as much as 50 percent more

Exploring Zinc

Food sources:

Red meat, some seafood, whole grains

Too much or too little:

UL = 40 µg/day

As little as 50 mg can cause stomach pains, nausea, vomiting, diarrhea

60 mg/day can inhibit copper absorption

Excessive amounts can suppress immune system, lower HDL cholesterol

Deficiency: hair loss, impaired taste, loss of appetite, diarrhea, delayed sexual maturation, impotence, skin rashes, impaired growth

Zinc Content of Selected Foods

Figure 8.27

Exploring Selenium

Part of class of proteins called selenoproteins, many of which are enzymes

Functions of selenoproteins:

Help regulate thyroid hormones

Act as antioxidants

May help fight cancer

Daily needs: adults: 55 µg/day

Food sources: meat, seafood, cereal, grains, dairy foods, fruits, vegetables

Amount varies depending on soil content

Exploring Selenium

Too much or too little:

UL = 400 µg/day

Too much can cause toxic condition selenosis

Symptoms: brittleness and loss of nails and hair, stomach and intestinal discomfort, skin rash, garlicky breath, fatigue, nervous system damage

Selenium deficiency is rare in United States

Deficiency can cause Keshan disease (heart damage): seen in children in rural areas that have selenium-poor soils

Selenium Content in Selected Foods

Figure 8.28

Exploring Fluoride

Functions:

Protects against dental caries

Helps repair enamel eroded by acids from bacteria

Reduces amount of acid bacteria produce

Provides protective barrier

Fluoridated drinking water has reduced dental caries in United States

Daily needs:

Men: 3.8 µg/day; women: 3.1 µg/day

Structure of a Tooth

Figure 8.29

Percentage of Americans Living in Communities with Fluoridated Water Supply, by State, 2006

Figure 8.30

Exploring Fluoride

Sources: foods are not a good source

Best source is fluoridated drinking water and beverages made with this water

Too much or too little:

Too little increases risk of dental caries.

Too much can cause fluorosis (mottling/staining) when teeth are forming during infancy/childhood.

Fluorosis of bones can occur when >10 µg/day is consumed for 10 or more years.

UL: adults:10 µg/day, much lower for infants and children

Exploring Chromium

Functions:

Helps insulin in your body

Increases effectiveness in cells

May improve blood glucose control, but no large study confirms this theory

Small study suggests chromium supplement may reduce risk of insulin resistance

FDA allows a Qualified Health Claim on chromium supplements, but label must state that evidence is not certain

Does not help build muscle mass

Exploring Chromium

Daily needs: men: 30 to 35 µg; women: 20 to 25 µg

Food sources: grains, meat, fish, poultry, some fruits and vegetables

Too much or too little:

No known risk from consuming too much

Deficiency is rare in United States

Chromium Content in Selected Foods

Figure 8.31

Exploring Iodine

Functions: needed by thyroid to make essential hormones

Thyroid hormones regulate metabolic rate; help heart, nerves, muscle and intestines function properly

Daily needs: adults: 150 µg/day

Food sources: iodized salt (400 µg/tsp)

Amount in foods is low; depends on iodine content of soil, water, fertilizer

Salt-water fish have higher amounts

Location of Thyroid Gland

Figure 8.32

Iodine Content in Selected Foods

Figure 8.33

Exploring Iodine

Too much or too little: UL = 1,100 µg/day

Excess iodine can impair thyroid function, decrease synthesis and release of thyroid hormones

Early sign of deficiency = goiter (enlarged thyroid gland)

Mandatory iodization of salt has decreased iodine deficiency in United States but not in other parts of world

Iodine deficiency during early stages of fetal development can cause cretinism (congenital hypothyroidism)

Exploring Manganese

Part of, or activates, many enzymes in body

Functions:

Helps metabolize carbohydrates, fats, amino acids

Aids bone formation

Daily needs: men: 2.3 µg/day; women: 1.8 µg/day

Food sources: whole grains, nuts, legumes, tea, vegetables, pineapples, strawberries, bananas

Too much or too little:

UL = 11 µg/day to avoid toxicity with Parkinson's disease-like symptoms

Manganese Content of Selected Foods

Figure 8.34

Exploring Molybdenum

Functions: part of several enzymes involved in breakdown of certain amino acids and other compounds

Daily needs: adults: 45 µg/day

Food sources: legumes, grains, nuts

Too much or too little:

UL = 2 µg/day, based on animal studies in which too much molybdenum caused reproductive problems

No cases seen in healthy individuals

Other Minerals

Arsenic, boron, nickel, silicon, and vanadium

Exist in body but essential role in humans not established by research

May have function for some animals

Tolerable upper levels set for:

Boron: 20 µg/day (10 times more than average American consumes)

Nickel: 1 µg/day

Vanadium: 1.8 µg/day

Table 8.1

Table 8.2

Table 8.3

Table 8.4

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