MineralsLecture 7

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

There are 3 major electrolytes:◦sodium◦potassium◦chloride

The electrolytes

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)