Minerals

Question 1

Folate (B9)

Answer 1

• precursor of tetrahydrofolate, coenzyme involved in generating precursors for DNA and protein synthesis
• hemopoietic B vitamin

Deficiency:

• neural tube defects in newborns of deficient mothers
• macrocytic anemia
• hyperhomocysteinemia (cardiovascular risk)

Suspectible:

• pregnancy
• elderly
• alcoholics
• patients with certain long term drug treatments
• people with genetic polymorphisms in folate metabolism

Question 2

Folate supplementation

Answer 2

• inadequate folate early in pregnancy appears to be associated with neural tube defects. Mothers may have inadequate folate without symptoms
• demand very high in pregnancy and lactation
• grain products enriched in folate have lowered the risk
• defiency inhibits DNA synthesis by decreasing availability or purines and dTMP
• anticonvulsant drugs and oral contraceptives may also interfere with absorption of folates

Question 3

Cobalamine (B12)

Answer 3

function:

• coenzyme in methionine synthesis and in conversion of methylmalonyl CoA to succinyl CoA
• needed in folate metabolism
• can be stored very effectively but deficiencies come from lack of absorption due to deficiency in intrinsic factor

Deficiency:
-pernicious anemia (megaloblastic anemia with demyelination)

Susceptible:
-elderly, patients with malabsorption diseases, long- term vegetarians

Question 4

Megablastic anemia

Answer 4

• large size of RBCs in presence of folate/vitamin B12 deficiency
• arises from a deficiency in nucleotides, leading to decreased DNA and RNA synthesis. Cells increase in size without dividing, and large immature RBCs do not carry sufficient oxygen
• pernicious anemia refers specifically to a B12 deficent anemia arising from lack of intrinsic factor

Question 5

Minerals

Answer 5

• inorganic compounds critical for human physiology
• many minerals are enzyme cofators, but they can also play structural roles in proteins or on their own
• categorized as macrominerals and microminerals based on level required (doesn’t correlate with importance)
• often work in parallel with vitamins, so supplements often contain both

Question 6

Cobalamine and cobalt

Answer 6

• cobalamine contains a cobalt
• B12 in food must be released from protein by acid hydrolysis in the stomach. It then must bind to intrinsic factor to be absorbed in the ileum

Question 7

Mineral classification

Answer 7

• Macrominerals:
• Potassium, Sodium, Chloride, Calcium, Phosphorus, Sulfur, Magnesium
• 100-200 mg/day

Microminerals:

• Iron, Copper, Zinc, Chromium, Iodine, Manganese, Selenium, Molybdenum, Fluoride, Boron
• lower 100 mg/day

Question 8

Calcium

Answer 8

Function:

• major component of bone
• signaling
• coagulation
• muscle contractions
• neurotransmission

Deficiency:
mild- muscle cramps, osteoporosis
severe- rickets

Susceptible groups:
-children, adult women, elderly

Question 9

Where does calcium come from and go?

Answer 9

• 98% of calcium is in bone and teeth
• hydroxyapatite is the basic mineral component of bones and teeth
• bone is the body’s calcium reservoir: bone releases Ca2+ if serum levels of insufficient
• 2% of calcium in rest of the body
• low serum calcium signals enhance intestinal absorption and stimulate bone resorption

Question 10

Osteoporosis

Answer 10

• osteoporotic bone from calcium deficiency is porous
• calcium intake during period when bone is reaching maximum density (age 10-35) is important to prevent osteoporosis
• even higher levels of calcium intake are required to maintain bone mass in postmenopausal women (exercise also helps main bone density)

Question 11

Magnesium

Answer 11

Functions:

• essential for many enzymes useing MgATP as substrate (usually transporters)
• present at high levels in bone

Deficiency:
-weakness, tremors, cardiac arrhythmia

Susceptible groups:
-alcoholics, patients taking diuretics or experiences severe vomiting and diarrhea

Question 12

Phosphorus

Answer 12

Functions:

• most present in phosphates
• Major component of bone (hydroxyapatite)
• constituent of nucleic acids, membrane lipids
• required in all energy-producing reactions

Deficiency:
rare- can result in rickets, muscle weakness and breakdown, seizure
-quite abundant in food supply

Question 13

Iron

Answer 13

Function

• O2/CO2 transport in hemoglobin
• oxidative phosphorylation
• cofactor in several nonheme iron proteins and cytochromes (redox properties of iron are important
• best sources are meat, dried legumes and fruit and iron enriched cereal products

Defiency:
-microcytic hypchromic anemia, decreased immunity

Susceptible:
-common in children and menstruating women, pregnant women, and elderly

Question 14

Iron absorption and distribution

Answer 14

• reduction of Fe3+ and Fe2+ is promoted by vitamin C in diet (Vitamin C deficiency causes mild anemia)
• Low pH in stomach helps release Fe3+ from ligands and make it bioavailable
• uptake of iron in mucosal cells of small intestine is regulated in response to iron-deficient or overload states
• iron is carefully escorted both in circulation and in cells because of the potential for inadvertent redox damage

Question 15

Major barriers to absorption

Answer 15

1) release of Fe3+ from food
2) availability of reducing agent to convert Fe3+ to Fe 2_

• although spinach does contain iron, it is so tightly chelated that it cannot be readily absorbed.
• the second requirement is often satisfied by vitamin C

-hepidin signals iron sufficiency and prevents export of Fe2+ from duodenal mucosal cell by downregulating the exporter

Question 16

Characteristics of iron-deficient anemia

Answer 16

• microcytic anemia- small, pale, red blood cells
• less hemoglobin is produced, and RBCs undergo more cell divisions in bone marrow waiting for hemoglobin synthesis
• patient symptoms: fatigue, pallor, weakness, dizziness

Question 17

Iron toxicity

Answer 17

• chemical properties as redox agents- if not localized properly they can catalyze product of ROS
• also one transition metal can replace another at an enzyme’s active site, compromising an enzyme’s activity
• Long term: Hemochromatosis
• iron overload leads to iron deposits in multiple tissues. Leads to compromised liver, pancreatic, and cardiac function
• ultimately can compromise mitochondrial function leading to lactic acidosis

Acute: iron overdose in children
-most common cause of death due to toxicity in children under 6 comes from consumption of adult iron supplements

Question 18

Copper

Answer 18

Functions:

• assists iron absorption through ceruloplasmin
• cofactor for enzymes required in collagen synthesis, fatty acid metabolism, and elimination of ROS

Deficiency:
-quite rare, symptoms include anemia, hypercholesterolemia fragility of large arteries, bone demineralization, demyelination

Susceptibility
-those with genetic Menkes syndrome or consuming excessive zinc

Question 19

Menkes’ disease

Answer 19

-iron deficiency disorder that comes from inherited mutations in a Cu- transporting ATPase ATP7A

Question 20

Wilson’s disease

Answer 20

• mutation in ATP7B, a relative ATP7A, but results in copper overload
• copper is not sequestered properly, and accumulates in liver with severe liver and nervous system symptoms. Results in liver failure and liver cancer

Question 21

Zinc

Answer 21

function:

• cofactor for over 300 metalloenzymes
• plays a structural role in many proteins (Zn finger domains)

Deficiency:
-poor wound healing, dermatitis, reduced taste acuity, poor growth and impaired sexual development in children

Suspectible groups: alcoholics, elderly, people with malabsorption or kidney disease

Question 22

Chromium

Answer 22

• function:
• component of chromodulin- facilitates insulin binding to its receptor

deficiency:
-impaired glucose tolerance (from reduced insulin effectiveness)

susceptible populations:
-those with impaired glucose tolerance, but Cr3+ hasn’t yet proven helpful in treatment of type 2 diabetics

Question 23

Iodine

Answer 23

• function:
• incorporated into triodothyronine (T3) and thyroxine (T4)
• regulates basal metabolic rate

Deficiency:

• goiter-enlarged thyroid gland (low I stimulates increased thyroid stimulating hormone)
• hyperthyroidism or hypothyroidism

Saltwater fish is an excellent dietary source of iodine

Question 24

Selenium

Answer 24

Function

• component of antioxidant enzymes (glutathione peroxidase)
• component of deiodinase enzymes involved in T3 and T4 metabolism

Deficiency:
-Keshan disease (in areas with little selenium in soil)- cardiomyopathy and cretinism

Question 25

Manganese

Answer 25

- part of arginase, pyruvate carboxylase, superoxidase dismutase

Question 26

Molybedum

Answer 26

-xanthene oxidase

Question 27

Fluoride

Answer 27

-incorportated into bones and teeth, strengthening them

Question 28

Boron

Answer 28

-involved in bone formation

Question 29

Sulfur

Answer 29

-component of amino acids and used in certain post- translational modifications

Question 30

Most common vitamin and nutrient deficiencies in the general population

Answer 30

- Children: iron and calcium - Teenagers- calcium and magnesium, possibly vitamin A, C and B6 - Women- iron, calcium, magnesium, vitamin B6, folate - Elderly- Vitamins B6, B12, D, possiblly zinc and chromium - Alcoholics- susceptibile to multiple deficiencies, but especially folate, B6, and thiamine -there are Drug-nutrient interactions that should be considered