chapter 8: minerals

water

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

intracellular fluids

inside cells

extracellular fluids

interstitial fluid between cells and fluid in the blood

electrolytes

minerals that help maintain fluid balance

importance of water

acts as universal solvent and transport medium, helps maintain body temperature, lubricant for joints, eyes; part of mucus and saliva, protective cushion for brain, organs, and fetus

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, and skin

insensible water loss

through evaporation from skin and when you exhale

sensible water loss

through urine, feces, and sweat

dehydration

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

dry mouth

thirst mechanism due to increased electrolyte concentration in blood: less water available to make saliva

blood volume decreases and sodium concentration increases in blood

thirst mechanism in which the brain triggers thirst mechanism and secretion of antidiuretic hormone (ADH) to reduce urine output, fluid inside cells moves into blood by osmosis

cornerstone method

measure dehydration by measuring body weight before and after exercise, weight loss = water loss

hyponatremia

a condition of too little sodium in the blood

water daily needs

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

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

tap water

perfectly safe, monitored by Environmental Protection Agency (EPA), provides fluoride and helps prevent dental caries

bottled water

very popular, most products conform to FDA requirements, may actually be tap water, high cost, various "designer" waters on the market

inorganic elements

minerals, needed in relatively small amounts

major minerals

(macrominerals) needed in amounts greater than 100 milligrams/day

trace minerals

(microminerals) needed in amounts less than 15 milligrams/day

overconsumption of minerals

can be toxic; the difference between recommended and excessive amount may be minimal, foods alone rarely provide excessive amounts (supplements cause the problem)

sodium

an electrolyte (charged ion) in blood and in the fluid surrounding cells, 90% consumed sodium comes from table salt and NaCl

sodium function

chief role is regulation of fluid balance, also transports substances such as amino acids across cell membranes

sodium daily needs

1,500 milligrams/day for adults under 51

sodium dietary guideline

<2300 mg per day

too much sodium

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

too little sodium

sodium deficiency is rare in healthy individuals consuming a balanced diet

blood pressure

a measure of force that blood exerts on the walls of arteries, systolic pressure/diastolic pressure, <120/80 millimeters Hg is normal

hypertension

high blood pressure, contributes to atherosclerosis, damages arteries leading to brain and kidneys, increasing risk of stroke and kidney disease, to control hypertension one should reduce weight, increase physical activity, and eat a balanced diet

the DASH diet

Dietary Approaches to Stop Hypertension

potassium functions

fluid balance: electrolyte inside cells (intracellular ion), muscle contraction and nerve impulse conduction, can help lower high blood pressure

potassium daily needs

women—2,600 milligrams/day

men—3,400 milligrams/day

potassium food sources

fruits and vegetables

minimum of 4 1/2 cups/day will help meet potassium needs, dairy foods, nuts, and legumes also good sources

too much potassium

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

hyperkalemia

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

too little potassium

can cause hypokalemia, may come from as result of excessive vomiting and/or diarrhea, anorexia and/or bulimia eating disorders

hypokalemia

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

calcium

most abundant mineral in body, more than 99 percent located in bones and teeth

calcium functions

helps build strong bones and teeth, plays a role in muscles, nerves, and blood

calcium daily needs

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

calcium food sources

milk, yogurt, cheese

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

3-300 rule for calcium intake

have three calcium-rich food servings daily, each calcium rich food source with 300 mg calcium

calcium upper limit

2,500 milligrams/day (ages 19-50); 2,000 milligrams (51+)

too much calcium

leads to hypercalcemia

hypercalcemia

impaired kidneys, calcium deposits in body

too little calcium

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

bone mineral density

test measures bone density, low score = osteopenia (low bone mass), very low score = osteoporosis

osteoporosis 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 risk factors continued

medications: glucocorticoids, antiseizure medications, aluminum-containing antacids, and 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)

phosphorus

second most abundant mineral in body, 85% in bones; rest in cells and fluids outside cells, including blood

phosphorus functions

needed for bones and teeth, important component of cell membranes, needed for energy metabolism and stores, part of DNA and RNA

phosphorus food sources

meat, fish, poultry, and dairy, abundant in diet

phosphorus upper limit

UL set at 4,000 milligrams/day for adults 19 to 50, 3,000 milligrams for those aged 51 or older

too much phosphorus

hyperphosphatemia, which can lead to calcification of

tissues

too little phosphorus

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

magnesium

another abundant mineral in body, about half in bones; most of the rest inside cells

magnesium functions

helps more than 300 enzymes, including energy metabolism, helps muscles and nerves function properly, reduces risk of type 2 diabetes

magnesium food sources

whole grains, vegetables, nuts

fruits; also milk, yogurt, meat, and eggs

magnesium upper limit

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

too much or too little magnesium

deficiencies are rare, but diuretics and some antibiotics can

inhibit absorption

chloride

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

chloride functions

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

chloride food sources

salt (NaCl) is main source

sulfur

component of other compounds in body, including the

vitamins thiamin, biotin, and pantothenic acid

sulfur functions

helps give proteins 3-D shape as part of amino acids methionine, cystine, and cysteine, sulfites used as food preservative

sulfur food sources

meat, poultry, fish, eggs, legumes, dairy, fruits, vegetables

too much or too little sulfur

no known toxicity or deficiency symptoms

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

iron functions

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

iron daily needs

men and women >50: 8 milligrams/day

women 19 to 50: 18 milligrams/day: higher due to iron lost during menstruation

iron food sources

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

iron absorption

iron status, form in food - heme vs. nonheme, acidity of GI tract vitamin C enhances absorption, other dietary components consumed with iron-containing foods

too much iron

from supplements can cause constipation, nausea, vomiting, and diarrhea, in the U.S. it is a a leading cause of accidental

poisoning deaths in children under six years, iron overload can damage heart, kidneys, liver, and nervous system

hemochromatosis

a genetic disorder, can cause iron overload

too little iron

most common nutritional disorder in world, anemia occurs when iron stores are depleted and hemoglobin levels decrease

anemia

symptoms can include: pale skin, fatigue upon exertion, poor temperature regulation, loss of appetite, apathy

most at risk: Infants, toddlers, chronic blood loss, vegans, runners, women of childbearing years

copper functions

important for iron absorption and transfer, synthesis of

hemoglobin and red blood cells

zinc functions

involved in function of more than 100 enzymes, taste acuity, treatment for common cold

zinc food sources

red meat, some seafood, and whole grains

too little zinc

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

selenium functions

act as antioxidants

selenium food sources

amount varies depending on soil content

fluoride functions

protects against dental caries and repair enamel, fluoridated drinking water has reduced dental caries in the United States

fluoride sources

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

too much fluoride

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

too little fluoride

increases risk of dental caries

chromium functions

helps insulin in your body and increases effectiveness in cells, does not help build muscle mass

iodine functions

needed by thyroid to make essential hormones

iodine food sources

iodized salt

too much iodine

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

too little iodine

goiter (enlarged thyroid gland), iodine deficiency during early stages of fetal development can cause congenital hypothyroidism

other minerals

arsenic, boron, nickel, silicon, and vanadium

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