HNSC Unit 8

water and minerals

Water

• most indispensable of all nutrients

  • can survive only a few days without water

• makes up 60% of adult body weight

  • arteries, veins, capillaries, cells, tissues, organs

Water Functions

• transport vehicle for nutrients and wastes

• universal solvent

• body’s cleansing agent

• lubricant for joints

• protection for sensitive tissue

• maintenance of body temp

Water Balance

• lose water everyday - must consume at least the same amount

Water Balance - Thirst

• pituitary gland signaled to release hormone - kidney shifts water back to bloodstream (urine output decreased)

• when blood too conc. or blood vol/pressure too low, hypothalamus initiates nerve impulses to brain to trigger thirst

Water Balance - Dehydration

• loss of water

• symptoms: thirst → weakness → exhaustion → delirium → can lead to death

DRI

• ~80% of daily need for water

• males: 13 cups of fluid from beverages and drinking water

• females: 9 cups of fluid

• remaining water need is met from foods consumes

• body produces water from the breakdown of energy yielding nutrients

Hard Water

• high conc. of Ca and Mg

• may protect against hypertension and heart disease

Soft Water

• principal mineral is Na

• may aggravate hypertension and heart disease

• may more easily dissolve certain contaminants

Water Safety

• may contain contaminants like bacteria, viruses, toxic pollutants, spills, heavy metals, organic chemicals

• public water systems remove some hazards (chlorine)

Health Canada Boil-Water Advisory

• issues by local public health unit when water becomes contaminated

Tap Water

• municipal water held to minimum standards for purity

Home Purifying Tap Water

• adequate job removing lead, chlorine, other contaminants; does not remove microorganisms that arent affected by chlorine

Bottled Water

• federally regulated; provinces can establish additional requirements; unpredictable in its mineral content

Body Fluids & Minerals

• most of body’s water inside the cells; some on outside

  • remainder fills blood vessels

• major minerals form salts

  • water follows salt

• cells move salts across their membranes

  • prevents collapse/swelling

Electrolytes

• compounds that partly dissociate in water to form ions (electrically charged particles)

• when electrolytes present in unequal conc. on sides of permeable membranes, water flows to more conc. side

Fluid and Electrolyte Balance

• proper amount and kind of fluid in body compartments

• to control the flow of water, the body must use energy to move the electrolytes from one compartment to another

Fluid and Electrolyte Imbalance

• e.g. vomiting, diarrhea

• severe illness can develop quickly - medical emergency

• cause of death in eating disorders

7 Major Minerals

• Ca, P, K, S, Na, Cl, Mg

Trace Minerals

• I, Fe, Zn, Cu, Se, Fl, Cr, Mn, Mo

Functions of Minerals

• electrolytes: Na, K, Cl

  • maintain water balance in cells and blood

  • Na&K: used in muscle contractions and nerve transmission

• Body Structure: Ca, P, Mg, F, Zn

  • bones, teeth

• structures of DNA, RNA, Phospholipids, and ATP

Protein Structure

• the protein and the elements are bound to make a specific shape and this function

Cell Signaling and Communication

• Ca moves across cells as a messenger, stimulating proteins and cell activity

Calcium

• 1% of Ca in Fluids in and around cells

• transport of ions over cell membs.

• nerve transmission

• maintenance of normal blood pressure

• muscle contraction

• blood clotting

• secretion of hormones

Calcium Regulation

• blood Ca conc. takes priority over Ca stored in bones

• if blood Ca conc. decreases, body adapts by:

  • mobilizing Ca from bones

  • increases absorption of Ca by SI

  • prevents loss of calcium from kidneys

Calcium and Bone Health

• highest attainable bone density developed by late 20’s to early 30’s

• after 40, begin to lose bone mass; however, loss can be minimized

• therefore, sufficient Ca intake in children and adolescents is important

Phosphorus - Functions

• maintenance of acid-base balance of cellular fluids

• part of DNA and RNA - tissue growth and renewal

• metabolism and energy containing nutrients

• help enzymes and vitamins take energy from nutrients

• structural part of phospholipids

• present in some proteins

Magnesium - Functions

• assists with operation of enzymes

• release and use of energy from nutrients

• affects the metabolism of other minerals: K, Ca, vitamin D

• forms part of protein making machinery in body

• proper functioning of muscles

• promotes resistance to tooth decay

Sodium - Functions

• chief ion used to maintain fluid volume outside cells

• maintenance of acid-base balance

• essential for muscle contractions and nerve transmission

• toxicity = hypertension

Sodium - Excess in Diet

• increases Ca excretion

• may directly stress a weakened heart

• may directly aggravate kidney problems

• possible increased risk of stomach cancer (asians)

Sodium Intake in Canada

• adults 19-30 consume avg. 6000-8500mg/day

• females tend to consume less

• top sources: meat, breads, pizza, pasta, processed foods

When High Amount of Sodium Consumption

• thirst ensure that enough water in consumed to restore sodium-water ratio

• kidneys filter out excess sodium in the urine

Potassium - Functions

• chief positive ion used to maintain fluid volume inside cells

• maintenance of fluid and electrolyte balance

• maintenance of cell integrity

• critical to maintaining heartbeat

Dehydration

• caused by potassium loss inside cells

• when brain cells lose potassium, no longer notice need for water

• caution with diuretics important

Chloride - Function

• helps sodium maintain fluid, electrolyte and acid-base balance

• part of hydrochloric acid - stomach acidity

  • protein digestion

Iodine

• part of thyroxine (thyroid hormone, regulates BMR)

• food sources: seafood, foods grown in rich soil

• additive: ionized salt, milk, baked goods

Iron

• part of hemoglobin (RBC) and myoglobin (muscle)

• needed for energy metabolism

• females need more (18g/day) than males (8g/day)

Physical Symptoms of Anemia

• weakness

• headaches

• pallor

• intolerance to cold

• pica

Sources of Iron

• meat, eggs, legumes

• fortified cereals, breads, pastas, soy products

• some fruits and veggies

• cooking with cast-iron

Iron Absorption

• absorb ~23% heme iron from meats

• absorb 2-20% non-heme iron from animal and plant foods depending in iron stores and dietary factors

Zinc - Functions

• works with every protein in the body

• helps enzymes to:

  • make parts of the cells’ genetic materials

  • make heme in hemoglobin

  • assist the pancreas to digest

  • metabolize CHO, PRO, and fat

  • release vitamin A from storage

Zinc - Deficiency

• fibre and phytates bind zinc

• affects all functions of zinc:

  • digestion impaired

  • immune function impaired

• even mild deficiency causes imbalances

• adverse effects on growth

Zinc - Toxicity

• loss of appetite, impaired immunity, death

• blocks copper and iron absorption

• pancreas secretes zinc-rich digestive juices - some are excreted

Selenium

• major role in protecting vulnerable body chemicals against oxidative destruction

• functions:

  • prevent formation of free radicals and oxidative harm to cells and tissues

  • activating thyroid hormone

• found in many foods

• deficiency is rare (some cancers, heart disease)

Fluoride

• not essential to life, but important for role in dental health

• functions:

  • prevents dental cavities

• primary source is portable tap water

  • ~40% Canadians have access to this

Chromium

• helps regulate glucose

• deficiency can cause diabetes-like condition with elevated blood glucose and impaired intolerance, insulin response, glucagon response

Copper

• helps hemoglobin and collagen

• assists enzyme with oxygen handling ability

• deficiency - disrupted growth in children and impaired immunity and blood flow through arteries