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Nutrition > Water-Soluble Vitamins > Flashcards

Water-Soluble Vitamins Flashcards

1
Q

Vitamin B12 deficiency is common with…

A

Low meat intake and old age

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2
Q

Symptoms of vitamin B12 deficiency include?

A
  • tingling
  • numbness
  • memory problems
  • other NS symptoms
  • diarrhea
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3
Q

What are vitamins?

A
  • organic compounds required to maintain health, by allowing for growth and reproduction
  • regulate body processes
  • many are coenzymes
  • often sensitive to light and heat
  • obtained in the diet through consumption of natural and fortified foods and supplements
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4
Q

How does a low-fat diet affect bioavailability of vitamins?

A
  • may inhibit absorption of fat-soluble vitamins because they require fat in diet to pass into bloodstream
  • packaged into chylomicrons
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5
Q

How else is bioavailability of vitamins impacted?

A
  • some water-soluble vitamins may need a carrier protein
  • provitamins forms may be absorbed requiring conversion to active form
  • interaction with other dietary components may also affect absorption
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6
Q

Grain products contain…

A
  • thiamin
  • riboflavin
  • niacin
  • pantothenic acid
  • vitamin B6
  • folate
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7
Q

Fruits and vegetables contain…

A
  • riboflavin
  • niacin
  • vitamin B6
  • folate
  • vitamin C
  • vitamin A
  • vitamin E
  • vitamin K
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8
Q

Plant oils contain…

A
  • vitamin E
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9
Q

Milk and alternatives contain…

A
  • riboflavin
  • vitamin A
  • vitamin D
  • vitamin B12
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10
Q

Meat & alternatives contain…

A
  • thiamin
  • riboflavin
  • niacin
  • biotin
  • pantothenic acid
  • folate
  • vitamin B12
  • vitamin A
  • vitamin D
  • vitamin K
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11
Q

Why do smokers have a high prevalence of inadequate vitamin C intake?

A
  • vitamin C protects against free radicals, which are increased with smoking
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12
Q

Fortification vs enrichment?

A
  • fortified foods have nutrients added that are NOT normally found in that food (ex. calcium fortified orange juice)
  • enriched foods have nutrients added BACK that have been removed in processing (ex. enriched white flour)
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13
Q

What are supplements?

A
  • source of vitamins in the diet
  • contain some combination of vitamins, minerals, herbs, amino acids, botanicals, extracts
  • cannot replace healthy foods
  • take caution as regulation is not as stringent as for drugs
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14
Q

Approximately ____% of vitamins are absorbed in small intestine.

A

40-90%

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15
Q

Which type of vitamins are less likely to be present at toxic levels?

A
  • water-soluble

- excreted when ingested in excess

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16
Q

What are other characteristics of water-soluble vitamins?

A
  • tend to be less stable
  • tissue depletion can occur more readily
  • most converted to coenzymes that aid in energy generation and hematopoiesis
  • deficiencies first appear in rapidly growing tissues (skin, tongue, nervous tissue)
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17
Q

Dietary composition often affects…

A

How much of a vitamin is available

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18
Q

What is the function of thiamin?

A
  • converted to thiamin pyrophosphate (TPP), required for glucose metabolism
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19
Q

What are the symptoms of thiamin deficiency?

A
  • Beriberi; characterized by lack of energy, weakness and neurological symptoms (acetylcholine synthesis also uses TPP)
  • can advance to neurological condition called Wiernicke-Korsakoff syndrome
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20
Q

What is a common cause of thiamin deficiency?

A
  • alcohol abuse
  • chronic alcoholism inhibits absorption
  • liver creates TPP, but alcoholism damages liver
  • people w AA also less likely to eat healthy foods w this vitamin
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21
Q

What foods is thiamin found in?

A
  • pork, lentils, grain products
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22
Q

What two molecules is riboflavin converted into?

A
  • flavin adenine dinucleotide (FAD)
  • flavin mononucleotide (FMN)
  • help w energy production and cellular respiration
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23
Q

What is the function of riboflavin?

A
  • energy production and cellular respiration
  • iron mobilization
  • conversion of vitamins (folate, niacin, vitamin B6, vitamin K) into active forms
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24
Q

Where is riboflavin deficiency most commonly seen?

A
  • chronic alcoholics with deficiency of other B vitamins
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25
Q

What are the symptoms of riboflavin deficiency?

A
  • poor wound healing
  • inflammation of the eyes, lips, mouth, tongue
  • confusion
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26
Q

Where is riboflavin found in the diet?

A
  • milk, pork, trout, grains, lentils
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27
Q

Condition resulting from niacin deficiency?

A
  • pellagra
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28
Q

Symptoms of pellagra?

A
  • dermatitis, dementia and diarrhea (3 D’s)
29
Q

What is niacin made from in the body?

A
  • made from tryptophan (essential amino acid) if adequate in diet
30
Q

Niacin-derived enzymes important in components of cellular respiration reactions?

A
  • oxidation-reduction coenzymes: nicotinamide adenine dinucleotide (NAD) and NADP
31
Q

What foods contain high levels of niacin?

A
  • peanuts, lentils, meat, rice
32
Q

What is biotin a component of?

A
  • pyruvate carboxylase, acetyl-CoA carboxylase and other carboxylases
33
Q

When can biotin deficiencies occur?

A
  • people who eat raw egg whites
34
Q

What do raw eggs contain?

A
  • avidin (binds tightly to biotin)
35
Q

What are symptoms of biotin deficiency?

A
  • thinning hair, depression, lethargy, loss of hair colour, nausea and hallucinations
36
Q

When/ where does deficiency occurs?

A
  • deficiency is are

- occurs due to B-vitamin deficiency

37
Q

What is the function of pantothenic acid?

A
  • part of coenzyme A (CoA), the acetyl CoA intermediate in carbohydrate, fatty acid and amino acid metabolism
  • involved in fatty acid and cholesterol synthesis
38
Q

What foods contain high levels of pantothenic acid?

A
  • found in most foods

- sunflower seeds, meat, dairy, fruit and veg, grains

39
Q

What is vitamin B6 also known as?

A
  • pyridoxal phosphate (active coenzyme of B6)
40
Q

Where is B6 needed?

A
  • necessary in amino acid metabolism, transamination, deamination and decarboxylation
  • involved in production of myelin sheath
  • hemoglobin synthesis
  • converts homocysteine to cysteine
  • white blood cell formation
41
Q

Where is vitamin B6 found in foods?

A
  • animal products
  • lentils
  • rice
42
Q

Symptoms of vitamin B6 deficiency?

A
  • neurological symptoms (due to its function as neurotransmitter synthesis or myelin formation)
  • headaches, depression, confusion, numbness in extremities, and seizures
  • anemia occurs due to role in synthesis of hemoglobin
43
Q

Vitamin B6 absorption can be affected by…

A
  • some drugs, such as alcohol and contraceptives
44
Q

What is homocysteine?

A
  • an intermediate in cysteine biosynthesis

- elevated levels linked to CV disease

45
Q

How are B vitamins implicated in CV disease?

A
  • some B vitamins required to convert homocysteine
  • folate and vitamin B12 convert homocysteine to methionine
  • vitamin B12 converts homocysteine to cysteine
46
Q

Where does vitamin B12 come from?

A
  • present only in animal products, made by bacteria, fungi, algae
47
Q

Where do vegetarians get B12 from?

A
  • fortified foods or supplements, or nutritional yeast
48
Q

What process must occur in order for vitamin B12 to be absorbed?

A
  • B12 comes into body bound to protein
  • pepsin in stomach releases B12 from proteins
  • cells in stomach lining release intrinsic factor
  • IF in upper intestine binds B12, allowing it to bind to receptors for absorption in lower
    intestine
  • need sufficient stomach acid to allow cleavage
  • small amount can be absorbed passively
49
Q

In the colon, B12 is synthesized by…

A

Microorganisms but cannot be absorbed

50
Q

What is pernicious anemia?

A
  • anemia resulting from lack of IF; autoimmune attack on the cells that create it
51
Q

What proportion of the population is vitamin B12 deficient?

A
  • 1/3

- especially vegetarians and the elderly

52
Q

What foods contain vitamin B12?

A
  • all animal products - meat and dairy

- not found in any plants

53
Q

What are the functions of vitamin B12?

A
  • B6 and B12 both necessary for formation of myelin sheath
  • coenzymes formed from B12 needed for breakdown of fatty acids and homocysteine to methionine conversion reaction
  • conversion reaction also allows regeneration of folate necessary for DNA synthesis
54
Q

What occurs in vitamin B12 deficiency?

A
  • increased blood levels of homocysteine
  • megaloblastic anemia (also seen in folate deficiency)
  • deficiency develops slowly because little is lost from body - reabsorbed from bile
55
Q

What hastens vitamin B12 deficiency?

A
  • atrophic gastritis
  • pernicious anemia
  • both result in impaired absorption and reabsorption
56
Q

What are the functions of folate?

A
  • makes coenzymes necessary for DNA synthesis (dividing cells) and metabolism of some amino acids
  • folate from diet must be converted to active form before absorption by vitamin B12
57
Q

What occurs in folate deficiency?

A
  • megaloblastic (macrocytic) anemia
  • neural tube defects if inadequate intake during pregnancy
  • also linked with heart disease because conversion of homocysteine to methionine does not occur
58
Q

What is megaloblastic anemia?

A
  • larger and fewer RBCs resulting from a problem with cell division
59
Q

Higher folate levels in blood correlate with…

A

Lower risk for breast and colorectal cancer

60
Q

What foods is folate found in?

A
  • lentils a good source
  • nuts and seeds
  • vegetables and fruits
  • many foods now fortified to prevent neural tube defects in infants
61
Q

What can result from excess folate?

A
  • can mask early symptoms of B12 deficiency
  • very high folate allows conversion of methyl folate to folate without need for B12
  • anemia due to B12 is prevented but low B12 interferes with myelin sheath synthesis - permanent damage can occur because treatable symptom of megaloblastic anemia does not appear
62
Q

What is the function of vitamin C?

A
  • coenzyme involved in reactions to form hydroxyproline and hydroxylysine – necessary for collagen stability and cross-linking (and prevention of scurvy)
  • coenzyme for the synthesis of bile acids, neurotransmitters, hormones and in fatty acid metabolism
  • important antioxidant, neutralizing damaging free radicals
63
Q

What foods is vitamin C found in?

A
  • fruits and veg

- oranges, kiwis, strawberries, broccoli, cantaloupe

64
Q

What are oxygen free radicals?

A
  • derived from oxygen
  • enter our bodies from foods and environmental toxins
  • also routinely generated by metabolic processes (ex. ETC)
65
Q

How do free radicals cause cell damage?

A
  • can damage cell membranes, DNA, proteins, and mitochondria
  • implicated in aging and diseases such as cancer and CVD
  • neutralization of free radicals minimizes possible damage
66
Q

How does vitamin C work as an antioxidant?

A
  • donates electron to free radical so stabilize it and neutralize it
  • regenerated by body (ex. dehydroascorbic to ascorbic acid)
67
Q

How is cancer risk and lifestyle related?

A
  • estimated that about 35% of cancers are preventable
  • exercise, eating well, maintenance of healthy body weight and moderation in alcohol consumption are ways to reduce risk
  • research is consistent with consumption of higher fibre foods, and those that contain more ω-3 fatty acids and antioxidants
68
Q

What two optical conditions can be prevented with higher antioxidant intake?

A
  • age-related macular degeneration

- cataracts

69
Q

What are the benefits of quitting smoking before age 40?

A

Avoids 90% of the excess mortality caused by smoking

Nutrition (21 decks)

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