Perspectives in Nutrition 5 th ed. Gordon M.Wardlaw, PhD, RD, LD, CNSD PowerPoint Presentation by Dana Wu Wassmer, MS, RD

Perspectives in Nutrition5th ed.

Gordon M.Wardlaw, PhD, RD, LD, CNSD

PowerPoint Presentation by

Dana Wu Wassmer, MS, RD

Chapter 11: Water and the Major Minerals

Water

• Comprise 50-70% of the body

• Intracellular fluid

– Fluid within the cell

• Extracellular fluid

– Interstitial

– Intravascular

Fluid Balance

• Controlled by the electrolyte concentration

• “Where ions go, water is sure to follow”

• Osmosis– Movement of water from a less concentrated to

a more concentrated solution

• Osmotic pressure– Amount of force to prevent the dilution

Movement of Water (Fig. 11-1)

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Functions of Water• Metabolic processes• Solvent• Body temperature regulation

– Water absorb any excess heat– Body secretes fluids via perspiration– Skin is cool as perspiration evaporates

• Removal of body waste– Via urine– Urea excretion– Avoid concentrated urine

• Amniotic fluid, joint lubricants, saliva, bile

Are You Drinking Enough?• Recommend 1ml per 1kcal• (Fig. 11-3)


The Thirst Mechanism• Not reliable• (Fig. 11-4)


Water Safety• Most drinking water are safe• The Environmental Protection Agency • Power to local and state authorities to advise

public• Rural areas may need to have their water tested• Chlorine and ammonia are added to kill most

microbes—I.e. Cryptosporidium• Chlorine can be evaporated via boiling or

standing

Toxicity of Water?

• Too much water without sufficient electrolytes intake

• More water than the kidneys can handle• Usually not a problem (people won’t drink

that much)• Overwhelms the kidneys• Headaches, blurred vision, cramps,

convulsions

Minerals

• Various functions

• Major minerals– Require >100 mg /day – Calcium, phosphorus

• Trace minerals– Require < 100 mg/day– Iron, zinc

Bioavailability of Minerals

• Not all ingested minerals can be absorbed

• Presence of binders and dietary fiber

• Animal products are better absorbed

• Mineral/mineral competition

• Presence of vitamins

Functions of Minerals

• Metabolic roles

• Cofactors

• Body growth and development

Food Sources of Minerals

• Plants

• Animals

• (Animals eat plants)

• Enrichment process adds iron

Risk for Mineral Deficiencies

• Calcium

• Iron

• Zinc

Toxicity of Minerals

• Especially with trace minerals

• Careful use of mineral supplements

• Avoid amounts above the Upper Tolerable Intake Levels

Sodium

• Table salt (NaCl): 40% sodium, 60% chloride

Absorption, and Excretion of Sodium

• 95% of ingested sodium is absorbed

• Absorbed from the stomach, small intestine and colon

• Excretion regulated by the kidneys

Blood Pressure and Sodium Regulator (Fig. 11-4)


Functions of Sodium

• Positive ion in extracellular fluid

• Aldosterone regulates sodium balance

• Key for retaining body water

• Participates in nutrient absorption

• Creates an electrical potential charge

• Muscle contraction

• Conduction of nerve impulses

Deficiency of Sodium

• Rare• Persistent vomiting/ diarrhea• Excessive perspiration (losing 2-3% of body

weight)• Depletion of sodium in the body• Muscle cramps, nausea, vomiting, dizziness,

shock, coma• Normally kidney will respond by conserving

sodium

Food Sources of Sodium

• 1/3 - ½ of intake is added to food by individual

• ½ - 2/3 is added by food manufacturers• Lower salt products available• Milk and Dairy products• Breads, hot dogs, lunch meats, soups,

sauces, snack foods• Sodium content listed on the labels

Sodium Needs

• Body only needs 100 mg/day

• Minimum requirement is 500 mg/day

• Daily Value is 2400 mg/day

• Typical intake is 4000-7000 mg/day

“Salt Sensitive”

• 10%-15% of adults are

• High sodium intake leads to high blood pressure

• Recommend 2-3 gm sodium per day

• Recommended for all individual

• You will adapt to a low-sodium diet

Potassium

• Positive ion in the intracelluar fluid

• Associated with lowering blood pressure

Absorption and Excretion of Potassium

• 90% of potassium consumed is absorbed

• Regulated by aldosterone and the kidneys

Functions of Potassium

• Fluid balance, nerve-impulse transmission

• Muscle contraction

Foods Sources and Needs for Potassium

• Found in fruits, vegetables, milk, grains, meats, dried beans

• Minimum requirement is 2000 mg/day


• Typical intake is 2000-3000 mg/day

• Excess potassium is excreted by the kidneys

Potassium Deficiency

• Rare

• Use of diuretics

• Alcoholics, anorexia nervosa, bulimia nervosa

• Loss of appetite, muscle cramps, confusion, constipation, irregular heart beat

Chloride

• Negative ion for the extracellular fluid• Absorbed in the small intestine and colon• Excreted through the kidneys• Components of hydrochloric acid (HCl), immune

response, nerve function• Excess is excreted by the kidneys/perspiration• Minimum requirement is 700 mg/day• Much is obtained from salt consumption• High intake may cause high blood pressure

Calcium

• 99% is in bones and teeth

• Makes up 40% of all the minerals present in the body

Absorption of Calcium

• Amount in the body is dependent on amount absorbed• Requires a slightly acidic environment• Duodenum is the site of absorption• Availability of vitamin D• Normally absorb 25% of calcium in food• Increase to ~60% during time of need (pregnancy,

infancy)• Estrogen increases absorption• Parathyroid hormone

Decrease Absorption of Calcium

• Rapid intestinal motility

• High fiber intake

• Excess phosphorus

• Vitamin D deficiency

• Presence of polyphenols (tannins) in tea

• Menopause

• Aging• Achlorhydria

How Blood Calcium is Regulated• Blood level is maintained at the price of bone

calcium• Parathyroid hormone - increases blood calcium

– Retains calcium from excretion – Increases calcium absorption via increase calcitriol– Increases calcium release from bone

• Lower blood calcium– Decreases parathyroid hormone and calcitriol– Calcitonin

Calcium Regulation (Fig. 9-9)Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Functions of Calcium

• Blood clot– Needed to convert prothrombin to thrombin

• Nerve impulses transmission– Transmitted at the site of the target cell

• Muscle contraction• Cell metabolism

– Binds with calmodulin– Activates various enzymes

Bone Structure

Hydroxyapatite (mature bone) Calcium released

Supports and strengthens

Collagen protein matrix parathyroid hormone +

1,25 (OH)2 vitamin D

Osteoblasts Osteoclasts

Bone Mass

• During growth, osteoblast exceeds osteoclast activity (make more than we break down)

• More bone mass in areas under higher stress• Peak bone mass reached between the age of

20-30• Bone loss begins in mid-adulthood• Significant loss at menopause

Building Higher Bone Mass

• Adequate diet

• Healthy body weight

• Normal menses

• Weight-bearing physical activity

• Moderate intakes of protein, phosphorus, sodium, caffeine

• Non-smoker

• Lower the use of certain medications

Structure of Bone (Fig. 11-8)


Calcium and Blood Clotting• Formation of fibrin

• (Fig. 9-13)


Transmission of Nerve Impulses (Fig. 11-9)


Muscle Contraction (Fig. 3-4)


Calmodulin System (Fig. 11-10)


Other Roles of Calcium

• May lowers blood pressure

• May reduce colon cancer

• May reduce PMS symptoms

• May lower blood cholesterol

• May reduce kidney stones

Osteoporosis

• Calcium deficiency

• “A pediatric disease with geriatric consequences”

• Leads to ~1.5 million fractures / year

• Factors to increase bone mass

Food Sources of Calcium

• Dairy products

• Kale, collard, mustard greens

• Calcium fortified foods

• Tofu (if made with calcium carbonate)

• Canned fish

Calcium Supplement

• Recommended for people who cannot incorporate Ca into their diets

• Not recommended with high iron meal• Calcium carbonate (40% calcium)

– For those with ample of stomach acid– Found in antacids

• Calcium citrate (21% calcium)– Enhance absorption due to acidity content– Recommended for elderly

Risk With Calcium Supplements

• Lead contamination

• No FDA regulation

• Oyster shell

• Bonemeal

• Look for United States Pharmacopoeia seal of approval

Calcium Needs


• Adequate Intake (based on 40% absorption) is 1000 -1200 mg/day for adults

• Adequate Intake is 1300 mg/day for adolescents (9-18 yrs. old)

• Average intake range from 600-800 mg/day for women and 800-1000 mg/day for men

Can You Get Too Much Calcium?

• Small intestine prevents excess from being absorbed

• Upper Level set at 2500 mg/day

• Kidney stones, calcium in the urine

• Hypercalcemia

• Calcification of tissue

• Less efficient absorption

Phosphorus• Body absorption is based on body’s need

(70%-90%)• Absorption enhanced by calcitriol• Passive absorption based on the phosphorus

concentration in the lumen • Excess excreted by the kidney• Component of ATP, cell membrane, and bone• May be needed in elderly to preserve bone

Functions of Phosphorus

• 80% found in bones and teeth

• Found in every cell

• ATP

• DNA, RNA

• Phospholipids

• Acid-base balance

Deficiency of Phosphorus

• Contribute to bone loss

• Decrease growth, tooth development

• Rickets

• Anorexia, weight loss

• weakness, irritability, bone pain

Food Sources of Phosphorus• Various foods• Dairy, bakery products, and meats• Some from food additives• Most difficult to limit intake of • RDA is 700 mg/day for adults• Daily Value is 1000 mg• Current intake exceeds RDA• Deficiency highly unlikely

Who is at Risk For Deficiency?

• Pre-mature babies

• Alcoholics

• Elderly with poor diets

• Long-standing diarrhea

• Use of aluminum-containing antacids (binds to phosphorus)

Toxicity of Phosphorus

• Problem for individuals with inefficient kidney function

• Phosphate ions bind calcium• Calcium-phosphorus precipitates in body

tissues• Upper Level is 3-4 g/day• May compound bone loss if calcium intake is

low

Magnesium

• Primarily in green leafy plants

• Absorption based on body’s needs (40%-60%)

• Absorption enhanced by vitamin D

• Kidneys regulate blood concentration of magnesium

• Alcohol increases loss in the urine

• Much stored in the body

Functions of Magnesium

• An enzyme activator• Activates ATP• Contributes to DNA and RNA synthesis• Potassium and calcium metabolism• Proper nerve and cardiac functions• Insulin release from the pancreas• May dilate arteries• May prevent heart rhythm abnormalities

Deficiency of Magnesium

• Develops slowly

• Rapid heartbeat

• Weakness, muscle spasms, disorientation, nausea, vomiting, seizures

• May increase the risk of osteoporosis

Food Sources of Magnesium

• Whole grains, vegetables, nuts, seeds

• Hard tap water

• Dairy, chocolate, meat

• RDA for women is 310 mg/day

• RDA for men is 400 mg/day

• Daily Value is 400 mg

• Average intake is lower than the RDA

Too Much or Too Little Magnesium

• Magnesium loss – Thiazide diuretic use– Heavy perspiration– Long-standing diarrhea or vomiting– Alcoholism– Disorientation, weakness, muscle pain, poor heart

function

• Toxicity is uncommon– Associated with kidney disorder– Weakness, nausea, malaise

Sulfur

• Nonionic and ionic forms

• Part of an organic compound

• Disulfide bridges

• Acid-base balance

• Drug detoxifying pathways

• Part of a natural diet, primarily from protein

• Used to preserve foods

Documents

Perspectives in Nutrition 5 th ed. Gordon M.Wardlaw, PhD, RD, LD, CNSD PowerPoint Presentation by Dana Wu Wassmer, MS, RD