Minerals Flashcards
What are minerals?
Inorganic elemental atoms that are essential nutrients
Not changed by digestion or metabolism
What are functions of minerals
Participation with enzymes in metabolic processes (cofactors)
Structural functions (Ca, P in bone; S in keratin)
Acid-base and water balance (Na, K, Cl)
Nerve & muscle function (Ca, Na, K)
Unique functions (e.g., heme, B12, thyroid hormones)
Bioavailability and regulation
Absorption
-Small intestine & large intestine
Regulation
-Kidneys & small intestine
minerals in foods
Found in all food groups
More reliably found in animal products
Often other substances in foods decrease absorption (bioavailability) of minerals
Oxalate, found in spinach, prevents absorption of most calcium in spinach.
Phytate, form of phosphorous in most plants makes it poorly available.
Macro/major minerals
Sodium, potassium, magnesium, calcium, phosphorus, sulfur, chloride
Present in body tissues at concentrations >50 mg/kg (50 ppm)
Requirements in g
micro or trace minerals
(body needs relatively less)
Chromium, manganese, iron, cobalt, molybdenum, copper, zinc, fluoride, iodine, selenium, silicon, tin, arsenic, nickel…
Present in body tissues at concentrations <50 mg/kg (50 ppm)
Requirements in mg or µg
factors that affect requirements
Physiological state/level of production Interactions with other minerals Most minerals have an optimal range --Below leads to deficiency symptoms --Above leads to toxicity symptoms Mineral content of soils dictates mineral status of plants
Regulatory functions of calcium
Stimulates blood clotting Muscle contractions Transmission of nerve impulses Vision Regulation of blood glucose Cell differentiation Cofactor for energy metabolism
structural functions of calcium
bones and teeth
Bones
Reservoir to maintain blood calcium
Osteoblasts & osteoclasts
Hydroxyapatite
Large crystal-like molecule
phosphorous
Component of cell membranes & walls
Found in all foods
Structural & functional roles in body
Energy metabolism
functions of phosphorus
Functions Similar to calcium (structure, blood pH) Vitally important in energy metabolism ATP, sugar phosphates Phosphoproteins Impact on environment has scientists revisiting nutritional requirements Reduce P in phytate P form Not as much an issue with ruminants
Metabolism & Regulation of Phosphorus in the Body
Small intestine
Vitamin D-dependent active transport
Simple diffusion
Concentrations controlled by:
Calcitriol, PTH, calcitonin
Potassium
Functions Regulation of osmotic (fluid) and acid-base balance Major cation of intracellular fluid Cofactor for several reactions in carbohydrate metabolism Major salt in ruminant sweat Increases requirement in heat stress Typically high in forages Regulated in kidneys (aldosterone)
sodium
Absolutely an essential nutrient, but has been “demonized” like cholesterol
Typical intakes way higher than what is needed in humans; added to livestock diets
Body usually gets rid of excess quite easily
functions of sodium and chloride
Electrolytes (acid/base balance)
Fluid balance
Nerve function
Muscle contraction
regulation of sodium and chloride in the body
Small intestine Sodium absorbed first Chloride second Sodium Absorbed with glucose Also actively absorbed in colon Water absorption
sulfur
Component of amino acids
Cystine, cysteine, and methionine for bioactive and structural proteins
Wool contains about 4% sulfur
Chondroitin sulfate is a constituent of cartilage
Deficiency is related to protein deficiency
magnesium
Functions Associated with Ca and P 70% of Mg in skeleton Enzyme activation (e.g., pyruvate dehydrogenase) Bioavailability Calcium Phospohorus
metabolism and regulation of magnesium
Stabilizes enzymes Energy metabolism Cofactor for over 300 enzymes DNA & RNA metabolism Nerve & muscle function
bio availability and regulation of trace minerals
Difficult to quantify biochemically
Bioavailability influenced by genetics, nutritional status, nutrient interactions, aging
Absorbed in small intestine
Deficiencies & toxicities rare
Content in plant foods depends on soil content
