Dietary Minerals and Electrolytes Overview

Dietary Minerals

Chemical Elements that cannot be formed by the body and are required in the diet.

Inorganic Minerals

Minerals that do NOT contain Carbon.

Mineral Charge

Minerals can carry a positive or negative charge which affects their interactions.

Mineral Combinations

Combinations of minerals can yield salts.

Mineral Requirements

Different minerals are needed in different amounts (range from less than 0.1mg to over 4g).

Mineral Interaction

Many minerals inhibit/activate each other's absorption.

Major Minerals

Minerals required in amounts greater than 100mg/day.

Trace Minerals

Minerals required in amounts less than 100mg/day.

Ultra-Trace Minerals

Minerals required in amounts less than 1mg/day.

Metabolic Functions of Minerals

Functions include enzyme cofactors, energy production, electrical conductivity, cell communication, electrolytes, fluid balance, bone and teeth health, protein structure, electron carriers, and oxygen transport.

Mineral Digestion

Many minerals in the diet are bound to proteins and require protein digestion in the stomach to release them.

Mineral Transport

Minerals are usually transported in their free form, complexed with other minerals (salts), or attached to protein carriers.

Body Storage of Minerals

The body has large stores of some minerals (e.g., Calcium and Phosphorus in bone) and can store trace minerals like iron and copper in organs such as liver, kidney, and spleen.

Calcium Sources

Sources include dairy, seafood with bones, some green vegetables, fortified foods, and supplements.

Calcium Adequate Intake

For ages 19-50 years: 1000 mg/day; for ages 51+ years: 1200 mg/day.

Calcium Absorption

Involves carrier-mediated active transport and paracellular diffusion.

Calcium Absorption Enhancers

Vitamin D (calcitriol), sugars and sugar alcohols, and protein.

Calcium Absorption Inhibitors

Fiber, phytic acid, oxalic acid, excessive divalent cations (Zn, Mg), and unabsorbed fatty acids.

Calcium Transport

Calcium is transported bound to proteins (albumin and prealbumin), complexed with sulfate, phosphate, citrate, or free in the blood.

Calcium Regulation

Extracellular calcium concentrations are tightly regulated by PTH, calcitriol, and calcitonin.

PTH

Parathyroid hormone that breaks down bone to release calcium into the bloodstream.

Calcium Tightly regulated by

PTH, Calcitriol, Calcitonin (opposite effect)

Bone mineralization

The process by which minerals are deposited in the bone matrix.

Blood clotting

The process by which blood changes from a liquid to a gel, forming a blood clot.

Muscle contraction

The process by which muscle fibers shorten and generate force.

Calcium deficiency

Rickets with a co-deficiency of vitamin D, Increased risk for osteoporosis, Hypertension, colon cancer, obesity

UL for Calcium =

2,500 MG/DAY (can cause kidney stones)

Phosphorus

A mineral essential for the formation of bones and teeth.

Sources of Phosphorus

Meat, poultry, fish, eggs, dairy, cola-type soft drinks, phosphate containing supplements.

RDA = 19+ years: 700mg/day

Recommended dietary allowance for phosphorus for individuals aged 19 years and older.

Digestion of Phosphorus

Hydrolyzed to inorganic phosphate. (Can be organic or inorganic)

Absorption of Phosphorus

Saturable, carrier-mediated active transport and diffusion.

Enhancers of Phosphorus absorption

Vitamin D and calcitriol.

Inhibitors of Phosphorus absorption

Phytic acid (less bioavailable), excessive magnesium, aluminum, calcium.

Functions and Mechanisms of Phosphorus

Bone mineralization, nucleotide/nucleoside phosphates, phosphoproteins, phospholipids.

Deficiency of Phosphorus

Rare; renal patients at risk.

Toxicity of Phosphorus

UL: 9-70 years = 4g/day; >70 years = 3g/day.

Magnesium

A mineral important for many biochemical reactions in the body.

Sources of Magnesium

Nuts, legumes, whole grains, green vegetables, coffee, tea, cocoa.

RDA for Magnesium

Men: 400 mg/day (19-30 years), 420 mg/day (31+ years); Women: 310 mg/day (19-30 years), 320 mg/day (31+ years).

Absorption of Magnesium

Saturable, carrier-mediated active transport and simple diffusion.

Transport of Magnesium

50-55% free, 33% bound to protein, 13% complexed with negatively charged ions.

Enhancers of Magnesium absorption

Vitamin D, protein, carbohydrates.

Inhibitors of Magnesium absorption

Phytic acid, fiber.

Competitors of Magnesium absorption

Calcium, phosphorus, potassium.

Functions and Mechanisms of Magnesium

>300 enzyme reactions, structural cofactor, allosteric effector. Involved in glycolysis, Kreb's Cycle, Beta-Oxidation, nucleic acid synthesis, DNA transcription

Deficiency of Magnesium

Pure deficiency has not been reported; risk increased by malabsorptive disorders, excessive alcohol or diuretic use, parathyroid disease, burns increase risk.

Low intaes with CVD, type 2 diabetes, high BP

Toxicity of Magnesium

Possible impaired renal function; UL = 350 mg/day (non-food sources).

Sources of Iron

Heme iron from meat, fish, poultry; non-heme iron from nuts, fruits, veggies, grains.

RDA for Iron

Men: 8mg; Women: 18mg (premenopausal), 8mg (postmenopausal).

Digestion and Absorption of Iron

Heme iron is absorbed intact by heme carrier protein (hcp 1); non-heme iron is reduced to ferrous iron for absorption (main transporter DMT1...when iron is high DMT1 reduces, when iron is low DMT1 increases)

Enhancers of Iron absorption

Sugars (fructose, sorbitol), acids (ascorbic, citric), meat, poultry, fish, mucin

Inhibitors of Iron absorption

Polyphenols, oxalic acid, phytates, calcium, zinc, manganese.

Transport of Iron

Free Fe2+ binds to transferrin for delivery to tissues. Free Fe2+ can generate harmful free radicals

Storage of Iron

Stored in ferritin and hemosiderin at liver, bone marrow, spleen.

Functions and Mechanisms of Iron

Essential for hemoglobin, myoglobin, cytochromes, and various enzymes, peroxides

Deficiency of Iron

Hypochromic microcytic anemia; vulnerable groups include infants, adolescents, menstruating females, pregnant women.

Toxicity of Iron

TUL = 45mg; acute toxicity from accidental overload. Hemochromatosis (chronic iron overload)

Sources of Zinc

Red meats, seafood, poultry, pork, dairy, whole grains, vegetables.

RDA for Zinc

Men: 11mg; Women: 8mg; Pregnancy: 11mg; Lactation: 12mg.

Digestion of Zinc

Hydrolyzed from amino/nucleic acids in stomach and small intestine.

Absorption of Zinc

Carrier-mediated process and passive diffusion with high intake.

Transport of Zinc

Bound loosely to albumin in blood.

Enhancers of Zinc absorption

Ligands (chelators) like citric acid, picolinic acid, amino acids, acidic environment

Inhibitors of Zinc absorption

Phytate, oxalate, polyphenols, folate, iron, calcium.

Storage of Zinc

Found in all organic tissues, especially liver, kidneys, muscle, skin, bones.

Functions and Mechanisms of Zinc

Zinc-dependent enzymes present in over 200 enzymes, regulation of transcription, cell replication, bone formation, skin integrity, cell-mediated immunity, host defense, carbohydrate metabolism...ZINC Finger = proteins with a secondary structure due to the presence of a zinc atom linked throguh cysteinyl or histidyl residues

Deficiency of Zinc

Increased needs in elderly, children of low income, vegetarians, and those with alcoholism.

Acrodermatitis enteropathica (defect in ZIP4)

Toxicity of Zinc

UL = 40mg; high levels can cause copper deficiency.

Food Sources of Copper

Organ meats, shellfish, nuts, seeds, legumes, dried fruits.

RDA for Copper

Adults: 900ug; Pregnancy: 1,000ug; Lactation: 1,300ug.

Digestion of Copper

Bound to organic components in food, released by gastric HCl and pepsin.

Absorption of Copper

Small amount via stomach; primarily absorbed in small intestine.

Enhancers of Copper absorption

Amino acids like histidine and cysteine.

Inhibitors of Copper absorption

Phytate, zinc, iron, excessive antacid ingestion.

Transport of Copper

Bound loosely to albumin in blood; binds to metallothionein in liver for storage.

Storage of Copper

Stored in liver, brain, kidneys, skeleton. Metallothionein - stores us to 12 copper atoms (high affinity for Zinc, higher for Copper)

Functions and Mechanisms of Copper

Ceruloplasmin for iron oxidation, superoxide dismutase as antioxidant, Cytochrome c Oxidase: ATP production

Deficiency of Copper

May be caused by excessive zinc consumption or kidney issues (nephrosis), GI malabsorption

Toxicity of Copper

UL = 10mg; Wilson's Disease is a genetic disorder characterized by copper toxicity.

Water

The universal solvent, is essential for life, able to dissolve different compounds

Properties of Water

Highly polar compound with positive and negative charges.

Water Intake

Males: ~2.5 Liters; Females: ~2.2 Liters of total beverages a day.

Sources of Water

Beverages, water from foods, small amount from metabolism (<10%).

Distribution of Water in the Human Body

60% of body weight is total body water; ⅓ is extracellular, ⅔ is intracellular.

Water Absorption

99.9% absorbed in the gut, primarily in the small intestine. Most (80-85%) is absorbed in the small intestine, the rest (15-20%) is absorbed in the colon

primarily absorbed through osmosis

Kidney Structure

Nephron is the functional unit, including Bowman's capsule and glomerulus.

Kidney Role

Filtration and urine formation, filtering about 180 Liters of blood per day. Each liter of blood is filtered about 22-25 times in a single day

Endocrine Control: Renin-Angiotensin-Aldosterone System

Regulates blood pressure and fluid balance. **** Understand diagram!!!

Electrolytes

Chemicals that conduct electrical impulses in the body.

Sodium

Most abundant extracellular cation.

Adequate Intake of Sodium

1500mg/day; typical intake is 3.5g.

Food sources of sodium

canned, processed and frozen foods/meals; major source = table salt

UP/DV =

2400mg

Sodium Absorption

3 pathways

1. The Na+/glucose co-transport - small intestine

2. electron-neutral Na+ and Cl- co-transport - small intestine and the proximal portion of the colon

3. electrogenic Na+ absorption - large intestine

* all 3 use ATPase to exit into the blood

deficiences of sodium

rare, associated with sweating

sodium is unique because

UP is LESS than DV; UL =2300mg/day

dietary sodium intake increases urinary calcium excretion

Pottasium is a

intracellular cation

sources of potassium

widespread in food

Absorption of potassium

>85% of potassium to be absorbed by passive diffusion or by a K+/H+ -ATPase pump

* stimulated by the hormoes insulin and catecholamines