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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