Micronutrients (Folate, K, B12)

Question 1

what is folate needed for?

Answer 1

• dna synthesis and repair
• has important role in cell division and growth
• helps convert vit b12 to its coenzyme form
• breaks down homocysteine (without homocysteine, blood clot formation and arterial wall deterioration increases. Increases heart disease)

Question 2

sources of folate?

Answer 2

leafy green veg
veg and fruits
eggs
orange

Question 3

structure of folate?

Answer 3

3 rings and glutamate

• polyglutamate (in food)
• monoglutamate (supplements)

Question 4

is folate bettwer absorbed in supplements of food?

Answer 4

x2 better absorption in supplements than food

Question 5

describe absorption and activation of folate

Answer 5

1. folate occurs as polyglutamate in foods
2. During digestion in the intestine: glutamates are broken off and methyl groups are added. Folate is absorbed and delivered to cells
3. folate is trapped in its inactive form in the cells
4. activation of folate: b12 removes and keeps the methyl group
5. both the folate and b12 are now active and available for DNA synthesis

Question 6

what compound does folate occur naturally in foods?

Answer 6

polyglutamate

Question 7

what does b12 need to be absorbed?

Answer 7

folate

Question 8

what is DFE?

Answer 8

dietary folate equivalents:

the amount of folate available to the body from naturally occuring sources, fortified foods, supplememts

Question 9

describe the bioavailability of folate in foods? and in supplements?

Answer 9

foods: 50%
supplements: 100% (on empty stomach)

Question 10

why is the folate need for pregnant women much higher?

how much do they need?

Answer 10

much higher because more multiplying cells.

need 400microgrames of folate

Question 11

DFE of folate for adults?

Answer 11

270 micrograms of folate

Question 12

why should pregnant women (or women wanting to become pregnant) take folate supplements?

Answer 12

• supplements have increased bioavailability
• they need 400 micro grams of folate (many don’t receive enough from their diet)
• they should take at least one month before until the end of the 1st trimester

Question 13

describe the incidence of neural tube defects?

Answer 13

• fetus cannot properly develop in early stages without adequate folate
• health Canada makes its mandatory to fortify grain products since many pregnancies are unplanned
• results because the neural tube (embryonic tissue that forms between brain and spinal cord) doesn’t close fully.

incidence: 400infants/year in canada

Question 14

describe spina bifida

Answer 14

• the result of a open neural tube defect
• can cause potential paralysis
• spinal fluid comes out of the spine because neural tube was not fully formed

-most sever when it occurs in the brain (anenlephaly)

Question 15

how to decrease the risk of neural tube defects?

Answer 15

have adequate folate intake (400 micro grams) at least 1 month before becoming pregnant.

Take supplements (0.4mg of folic acid) because it’s difficult to obtain enough folate even from a healthy diet

Question 16

what should you consider before fortifying for a whole population?

Answer 16

• can you reach the population who needs it?
• can you provide enough to fix the problem without endangering others (take into account the UL of other population groups)

Question 17

describe the role of vit b12

Answer 17

vit b12 coenzyme removes a methyl group to activate folate (and activates itself)

DNA synthesis and regeneration of amino acid depends on folate and b12.

b12 is important for growth of sheaths that protect nerve fibers, bone cell activity and metabolism

Question 18

describe anemia due to folate deficiency

Answer 18

results in fewer but larger (large nucleus) and irregularly shaped RBC that can’t carry O2 or travel efficiently

macrocytic anemia

can also be caused by b12 deficiency because folate can’t be activated

Question 19

describe the use of intrinsic factor with b12

Answer 19

1. in the stomach, HCL and pepsin (digestive enzyme) release vit b12 from food
2. stomach secretes intrinsic factor
3. vit b12 passes to small intestine where it binds with intrinsic factor (a complex is formed)
4. b12 and intrinsic factor complex is recognized by receptors (note. b12 is not recognized without the intrinsic factor)
5. intrinsic factor is degraded and b12 is absorbed into the blood stream

Question 20

describe b12 deficiency

primary and secondary deficiency?

Answer 20

• most deficiencies reflect inadequate absorption, not inadequte intake
• causes macrocytic anemia (results in large and immature RBC)
• can cause irreversible neural damage (b12 is needed to protect nerve fibers and promote growth)
• inadequate absorption occurs because:
  1. lack of HCL (vitamins can’t be released from dietary proteins)
  2. lack of intrinsic factor (vitamin cannot be absorbed). Intrinsic factor decreases as you grow older

primary deficiency:

• vegans (low b12 intake)
• b12 stores can last up to 3 years and can be recyled (thus primary deficiency is rare and slow to develop

secondary deficiency:

• caused by lack of intrinsic factor
• cause of pernicious anemia (looks the same as megaloblastic RBC)

Question 21

what is pernicious anemia

Answer 21

reflects a vit b12 deficiency caused by a lack of intrinsic factor.

causes large and immature RBC

symptoms: muscle weakness and neurological damage

“pernicious” = destructive

Question 22

sources of b12?

Answer 22

only animal products: ie. meat, liver, tuna, cheese

Question 23

what metal ion is in the center of the b12 structure?

Answer 23

cobalt

Question 24

why is it difficult to develop a primary deficiency of b12?

Answer 24

b12 stores can last in the body for up to 3 years

b12 can be recycled in the body

Question 25

how does folate “mask” a b12 deficiency?

Answer 25

• RBC are first to be affected by a vit b12 or folate deficiency
• adding more folate can fix the RBC, but can’t stop the damage to nerve fibers from b12 deficiency
• result: blood shows no sign of deficiency, but damage is still happening

Question 26

what individuals are at risk of primary b12 deficiency?

Answer 26

vegans (no dietary b12 intake)

infants or pregnant vegans can possibly have nerve system damage during fetus development

Question 27

how do folate, b12 and b6 affect risk of heart disease?

Answer 27

low vit b6 + b12 + folate = high homocysteine levels = risk factor for atherosclerosis and blood clots = cardiovascular disease + strokes

no b12 + folate = build up of homocysteine.

no b6 = homocysteine can’t become cysteine

(refer to diagram)