Lecture 7. Small, naturally occurring, inorganic, chemical elements Regulate body processes Give structure to things in the body No calories (energy)
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Small, naturally occurring, inorganic,
chemical elements Regulate body processes Give structure to things in the body
No calories (energy) Cannot be destroyed by heat
What are minerals?
Major minerals◦Calcium◦Phosphorus◦Magnesium◦Electrolytes (sodium, chloride, potassium)
◦sulfur◦macrominerals are essential at levels of 100mg or more per day for human adults
Trace minerals◦Chromium◦Copper◦Flouride◦Iodine◦Iron◦Manganese◦Selenium◦Zinc◦microminerals
Categories of minerals
Sodium (Na)Sodium is the principal cation in extracellular fluids
functions include: osmotic equilibrium (fluid balance)
acid-base balance carbon dioxide transport
cell membrane permeability
muscle irritability
food sources: table salt, salty foods (potato chips, pretzels, etc.), baking soda, milk.
RDA for adults: 1.1 to 3.3 gm/day
deficiency:dehydrationacidosistissue atrophy
excess:edema hypertension
Potassium (K) deficiency (hypokalemia)
causes: increased renal excretion
(diuretics)primary aldosteronismsevere vomiting and
diarrheacutaneous losses via
perspiration• excess(hyperkalemia)
causes:sudden increased intakesevere tissue trauma and burns, acute and chronic acidosis
•Food sources: vegetables, fruit (bananas), whole grains, meat, milk; RDA for adults: 1.5 - 4.5 gm/day
•The principal cation in intracellular fluid•functions:
buffer constituentacid-base balancewater balancemembrane transportneuromuscular irritability
Chloride (Cl) an essential anion closely connected with sodium in foods, body
tissues and fluids and excretions readily absorbed along with sodium important for osmotic balance, acid-base
balance and in the formation of gastric HCl
Deficiency of chloride: hypochloremic alkalosis hypovolemia pernicious vomiting psychomotor disturbances
Calcium (Ca) the most abundant of the minerals the 5th most abundant element in
the body needed by all cells found in largest amounts in bones
(90%)
controlled by parathyroid hormone (PTH), calcitonin and vitamin D
about 1/2 is in the ionized form in serum the other 1/2 forms calcium citrate complex
function of calcium:◦structural unit of bones and teeth◦contraction and relaxation of muscles◦stabilizes nervous tissue low calcium --- irritable nerves --- tetany high calcium --- depresses the nervous irritability
◦required for blood clotting◦activates various enzymes (glycogen
phosphorylase kinase, salivary and pancreatic amylase)
RDA◦adult: 800 mg/day◦pregnacy and lactation: 1200 mg/day
Calcium
Phosphorus is the second most abundant mineral in the body
required in many phases of metabolism foods rich in calcium are also richest in
phosphorus (milk, cheese, eggs, beans, fish)
RDA for phosphorus is established on the basis of a 1:1 relationship with calcium
Adults: 700 mg/dayPregnancy and lactation: Younger than 18: 1250 mg/dayOlder than 18: 700mg/day Generates energy
Regulate energy metabolism Component of bones, teeth Part of DNA, RNA (cell growth, repair)
Phosphorus
Part of 300 enzymes (regulates body functions) Maintains cells in nerves, muscles Component of bones Best sources are all green plants (chlorophyll); meats RDA: 350 mg/day
◦pregnancy and lactation: 450 mg
Magnesium•second most plentiful cation in intracellular fluids•~50% of total amount in bone•~45% in muscle and nervous tissue•~ 5% in extracellular fluids
Deficiency◦decreased iron
absorption ◦neutropenia ◦bone demineralization
◦failure of
erythropoiesis sources
liver, shellfish, whole grains, cherries, legumes, nuts
Copper (Cu)
important trace mineral
component of several enzymes
needed to form hemoglobin and collagen
Considered essential because of its beneficial effect on tooth enamel
Benefits include: less dental caries, stronger bones, reduction in osteoporosis
In large quantities it is deleterious to teeth; dental fluorosis: chalky, dull white patches and mottling of teeth
1 to 2 parts per million is adequate for drinking water
Fluorine
Main sources include drinking water and plants (spinach, lettuce, onions)
Average daily intake: 1.5 – 4.0 mg/day
iodine is necessary for the formation of thyroid hormones (T-4 thyroxine and T-3 triiodothyronine)
deficiency of iodine is manifested by a goiter (enlargement of the thyroid gland)
salt water fish and seaweeds are a good source of iodine
to prevent the development of endemic goiter, table salt has been spiked with sodium iodide
Iodine
Cr III may act as a cofactor for insulin, enhancing glucose utilization
deficiency leads to impaired glucose tolerance (glucose tolerance factor)
chromium may have a role in type 2 diabetessources: corn oil, whole-grain cereals, drinking
water (variable)RDA: 0.05 – 0.2 mg frequently available in pharmacies as chromium
picolinate
Chromium
ManganeseDeficiency leads to:
Weight lossTransient dermatitisNausea and vomitingChanges in hair color
Sources: blueberries, wheat bran, beet greens, lettuce, legumes, fruit
RDA: 2.5 – 5.0 mg
Maganese is an activator of several different enzymes: Phosphoglucomutase Isocitric
dehydrogenase Cholinesterase Intestinal peptidase Carboxylases ATPases
However, magnesium and cobalt can replace Mn in several enzymes
Types of body iron (Dietary Iron)◦ Heme iron (animal source) hemoglobin, myoglobin, catalases, peroxidases,
cytochromes (a, b and c – involved in electron transport), cytochrome P450 (involved in drug metabolism) ,
◦Non-heme iron (vegetables/cereals) Ferritin, transferrin
Enzymes—methane monooxygenase (oxidizes methane to methanol), Ribonucleotide reductase (reduces ribose to
deoxyribose; DNA biosynthesis)
Iron (Fe)
heme iron◦ meats◦ poultry◦ fish
20-23% of heme-iron is absorbable
non-heme iron◦ vegetables◦ fruits◦ legumes◦ nuts◦ breads and cereals
only ~ 3 of non heme iron is absorbed
Food Iron
average diet contains 10 - 15 mg of iron per day
a normal person absorbs 5 -10% of this iron or 0.5 - 1.0 mg daily
occurs in upper part of small intestine also requires copper ferrous is better absorbed than ferric form iron absorption increases in response to low
iron stores pregnant women: 3 - 4 mg per day
Iron absorption
stored in 2 forms: ferritin (a water soluble complex consisting of a
core of ferric hydroxide and a protein shell (apoferritin)
hemosiderin (a particulate substance consisting of aggregates of ferric core crystals)
stored in liver, spleen, bone marrow, intestinal mucosal cells and plasma
Iron distribution and storage
Causes:◦excessive blood loss (parasitic,
accidental): is most common cause◦rapid growth in children with limited
intake of iron◦malabsorption gastric resection sprue
◦increased metabolic requirement pregnancy, lactation or neoplasia
IRON DEFICIENCY
Initial symptoms easy fatigability lack of appetite headache dizziness palpitations
then: hypochromic-microcytic anemia microcytosis (small RBCs) hypochromia (poor fill of hemoglobin) poikilocytosis (bizarre shapes) anisocytosis (variable/unequal sizes)
IRON DEFICIENCY
hematology (microcytic hypochromic cells) low serum iron low serum ferritin ( indicates low body
stores) low hemosiderin high total iron binding capacity (TIBC)
Diagnosis of iron deficiency
give 200 - 400 mg of iron per day up to 25% of the iron preparation may be
absorbed
Treatment of iron deficiency
parenteral iron is used in patients who have had bowel resections or in cases of inflammatory bowel disease◦normally given IM (painful)
oral iron causes black stools, constipation, cramping
do not administer with antacids or metal chelators (tetracyclines)
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