NS 315: Nutritional BiochemistryUnit 9: Minerals

Jeanette Andrade MS,RD,LDN,CDE

Kaplan University Instructor

Objective

• What are we going to be learning about tonight? A lot– Electrolytes: Sodium, Potassium– Bone Minerals: Calcium, Phosphorus, Magnesium– Antioxidants: Iron, Zinc, Selenium

Definitions• Electrolytes: substances that become ions in solution and

acquire the capacity to conduct electricity• Cation: positive charged ion• Anion: negative charged ion• Hydroxyapatite: calcium phosphate salt• Antioxidant: Reduces oxidative damage such caused by free

radicals• Reactive Oxygen Species: molecules and ions of oxygen that

have an unpaired electron• Zinc Finger Motif: sequence of approximately 30 amino acids,

forming a helix-turn-helix, believed to form a structure that includes tetrahedrally coordinated zinc (II) ions

Sodium

• Major positive cation in fluid outside of the cells• Regulates total amount of water in the body • Transmission of sodium in and out of cells regulates

brain, nervous system and muscles functions• Normal blood sodium level is 135-145 mEq/L• What can happen if there is too much sodium in the

cells or too little?

Potassium

• Major cation found inside cells• The proper amount of potassium is essential for

regulation of heart rate and muscle function• Normal lab values are 3.5-5.0 mEq/L• What happens if there is too little potassium or too

much potassium in cells?

Sodium- Potassium PumpNot really a cycle, this diagram is depicting active transport of molecules across a membrane. Active transport is coupled to ATP hydrolysis to obtain enoughenergy to transport ions against their concentration gradient.

outside

inside

Plasma membrane

NEED ACTIVE TRANSPORT TO PUMP AGAINST A GRADIENT

Bone Minerals: Calcium

• Accounts for 1-2% of adult human body weight• Body stores 99% of calcium in bones and teeth• It is needed to contract and expand muscles and

blood vessels

Bone Minerals: Calcium

• RDA: 19-70 year old males need 1000-1200 mg of calcium per day

• RDA: 19-70 year old non-pregnant/lactating females need 1000-1200 mg of calcium per day

• What foods tend to have calcium in them?

Bone Minerals: Calcium

Toxicity• Not from high intake of

calcium from foods, but from supplements-

• Kidney stones occur from an increased calcium excretion from kidneys

Deficiency• Abnormal parathyroid

function and rarely due to low dietary intake since calcium is a large reservoir in bones

• Chronic kidney disease, vitamin D deficiency, low magnesium in blood

• Chronically low dietary calcium intake may prevent peak bone mass

Bone Minerals: Phosphorous

• Majority of phosphorous is found as phosphate within the body

• 85% of phosphorous is found within the bone• Major structural component of bone in the form of

hydroxyapatite• What else is phosphorus important for within our

bodies?• RDA for males and females 19-70 year old 700 mg/day• What foods contain phosphorous?

Bone Minerals: Phosphorus

Toxicity• Calcification of non-skeletal

tissues- most commonly the kidneys

Deficiency• Loss of appetite, anemia,

muscle weakness, bone pain, rickets, osteomalacia, and can possibly lead to death

Bone Minerals: Magnesium

• 60% is within the skeletal structure, 27% within the muscles, 6-7% within the cells and 1% outside of cells

• Magnesium is required for ATP synthesizing protein in the mitochrondrion

• What other important processes is Magnesium important for?

• What foods contain Magnesium?• RDA for males 31-70 years old: 420 mg/day• RDA for females 31-70 years old: 320 mg/day

Bone Minerals: Magnesium

Toxicity• Not with foods, but with

salts- magnesium salt– Main problem diarrhea

Deficiency• Rare due to kidneys are

able to reduce urinary excretion when intake is low

• Occur with gastrointestinal disturbances, renal disorders, chronic alcoholism, age

Antioxidants: Iron

• Oxygen transport and storage• Electron transport and energy metabolism• Antioxidant: why?

– Catalase and peroxidase are heme containing enzymes that protect cells against an accumulation of harmful hydrogen peroxide (ROS)

– White blood cells engulf bacteria and expose them to ROS in order to kill them

– We produce or own disinfectant (clorox)

Antioxidants: Iron

• What foods contain Iron?• RDA for males 19-70 years old: 8 mg/day• RDA for females:

– 19-49 years old: 18 mg/day– 50-70 years old: 8 mg/day

Antioxidants: Iron

Toxicity• Accidental overdose with

iron containing products• Genetic disorders usually

are the cause– Hereditary

Hemochromotosis– Hereditary anemias

Deficiency• Most common deficiency in

the world, 3 levels of iron deficiency– Storage iron depletion– Early functional iron

deficiency– Iron deficiency anemia

Antioxidants: Zinc• Zinc functions in the cell can be divided into 3 categories:

– Catalytic: enzymes depend on Zinc for reactions– Structural: for proteins and cell membranes; Zinc finger

motif– Regulatory: Zinc finger motif regulates gene expression by

acting as transcription factors• Antioxidant: Why?

– Some studies suggest that Zinc is a protective factor against atherosclerosis by inhibiting the oxidation of LDL by cells or transition metals (copper, iron)

– Protect cells against Tumor Necrosis Factor induced cell injury

Antioxidants: Zinc

• What foods contain Zinc?• RDA for males 19-70 years old: 11 mg/day• RDA for females 19-70 years old: 8 mg/day

Antioxidants: Zinc

Toxicity• Occurs from consumption

of food or beverages that have been contaminated with zinc released from galvanized containers

Deficiency• Severe: generally from a

genetic disorder• Mild: generally children

from developing countries, however occurs in pregnant, anorexics, aging individuals, celiac disease and irritable bowel disease

Antioxidants: Selenium

• Selenoproteins:– Glutathione peroxidases– Thioredoxin reductase– Iodothyronine deiodinases

• Antioxidant: Why?– Glutathione peroxidase- antioxidant enzymes that reduce ROS by

coupling their reduction to the oxidation of glutathione– Thioredoxin- Thioredoxin reductase participates in the

regeneration of several antioxidants

Antioxidants: Selenium

• What foods contain Selenium?• RDA for males and females 19-70 years old:

– 55 uG/day

Antioxidants: Selenium

Toxicity• Accidental or suicidal

ingestion of grams of selenium

Deficiency• Decreased activity of

glutathione peroxidase, thioredoxin reductase and thyroid deiodinases

• Chronically ill patients receiving total parenteral nutrition (TPN)

• Treating metabolic disorders such as phenylketonuria (PKU)

Vit E

Vit E

CoQ10 CoQ10

LOOH

Cyt-b5reductase or NQO1

NAD(P)H+H+

NAD(P)+

LOOH

LOH

Vit C Vit C

Detoxification

Extracellular Space

Cytosol

Plasma Membrane

2 GSH

GSSG

GSH reductase

NADPH NADP+

Glucose-6-P

6-P-gluconate

G-6-PDH

GSH- Se Px

PLA2

Exogenous radical-X

O2

O

O

Endogenous radical-X

NADH ASCR reductase

Minerals/metals Fe Se Vitamins Niacin Vitamin E Vitamin C Other Coenzyme Q Lipoic acid

Burgess, J. R. and J. E. Andrade (2006). Antioxidant Effects of Citrus Flavonoid Consumption. Potential Health Benefits of Citrus. B. S. Patil, E. G. Miller, N. D. Turner and J. S. Brodbelt. Washington, DC, An American Chemical Society Publication.

Example of antioxidant control systems of oxidative stress in cells