Exam 3

panthothenic acid B5

coenzyme in acetyl CoA formation, deamination, and beta oxidation

panthothen

everywhere in greek; needed everywhere in body for function

pantothenic acid is abundant in

meat, eggs, whole grains, legumes

pantothenic acid is damaged by

exposure to heat and low or high acid conditions; deficiency is rare

pyridoxine B6

needed to produce and maintain myelin coating on nerve cells, needed for transamination reactions; lowers homocysteine (CVD)

pyridoxine active coenzyme

pyridoxal phosphate

pyridoxal phosphate is used for

acitivty of over 100 enzymes involved with carbohydrate, fat, and protein metabolism

homocysteine levels

elevated levels impact structure and function of blood vessels; increased CVD risk

individuals born with homocystinuria develop..

atherosclerosis at a young age

vitamin B6 promotes the formation of..

cysteine from homocysteine; deficiency increases levels

vitamin B6 deficiency

neurological symptoms, anemia from impaired hemoglobin synthesis

toxicity from B6 can cause

nerve damage

nerve damage from vitamin B6 toxicity

pain and numbness in extremities from more than 1g/day, some inability to walk from 2-6 g/day; high dose supplements OTC available 100 mg/day

biotin B7

coenzyme for group of enzymes that adds acid group COOH to molecules; needed for citric acid cycle and gluconeogenesis as well as production of fatty acids and some AA

dietary sources of biotin

liver, egg yolks, yogurt, nuts

biotin deficiency is

not common; observed in individuals with malabsorption, protein energy malnutrition, tube feeding without it

biotin deficiency also observed in individuals who use..

anticonvulsant drugs in long term, raw egg whites

symptoms of biotin deficiency

hair loss, red skin rash, depression, lethargy

folate B9

folic acid; readily absorbed and found primarily in fortified foods and supplements

folate takes longer to absorb because of

removal of multiple glutamate molecules

primary dietary source of folate

lentils

recommended dietary allowance of folate for pregnant women

600 mcg per day (highest recommendation)

folate is essential especially for

pregnant women; allows for normal cell division into red blood cells

folate deficiency can cause

spina bifida; lump in the back of an infant

active form of folate formed B12 is needed to prevent

homocysteine formation

active folate results in conversion of homocysteine to

methionine

cobalamin B12

necessary for proper absorption of iron in body; made by bacteria and accumulates in animals

B12 is found almost exclusively in

animal products; not in plants unless contaminated or fortified

bacteria in human _ produces B12 but can’t be..

colon; absorbed

vitamin B12 and vegans

must consume supplement vitamins or eat fortified foods

stomach is critical for

absorption in intestine

intrinsic factor of stomach

necessary for efficient B12 absorption

help release vitamin B12 from food proteins in stomach

acid and pepsin

intrinsic factor is release by

cells in stomach lining; binds to B12 in duodenum

B12 function

needed to convert folate to active form for DNA synthesis to precent anemia

folate and B12 both needed to

convert homocysteine to methionine; if either deficient, levels rise

B12 is stored

more efficiently than other B vitamins

B12 deficiency is due to

poor absorption rather than low intake

supplemental folic acid

masks B12 deficiency; anemia won’t develop but irreversible nerve damage can develop

vitamin C ascorbic acid

antioxidant and coenzyme; maintains immune system, production of connective tissue, aid in iron absorption from plant sources

vitamin C can be destroyed by

oxygen, light, heat, contact with copper or iron cookware

acid in juice

prevents vitamin C degradation

dietary sources of vitamin C

juices and fruits

scurvy

vitamin C deficiency disease

scurvy causation

weak collagen, blood vessels rupture, gums; was a problem for armies and explorers so lime or lemon juice required in rations for british sailors

vitamin C UL

2000 mg; excess excreted in urine, nausea and GI distress

highest amount of vitamin C in body is found in

immune cells

vitamin C doesn’t reduce cold incidence but

reduces symptom duration

choline

essential nutrient; not classified as a vitamin

choline is found in

eggs, meat, and dairy products as phospholipids

choline is needed for

neurotransmitter acetylcholine, cell membranes, lipoproteins, and homocysteine metabolism

choline deficiency

fatty liver and muscle damage in adults; fetal brain development impaired in pregnancy

dietary vitamins

organic compounds essential in diet to promote growth and health maintenance

micronutrients

required in small amounts

if lacking in diet

deficiency symptoms occurs

if restored in diet

deficiency symptoms resolve (most reversible)

almost all foods contain

some vitamin

food processing can cause

vitamin loss

plant foods are not a good…

source of vitamin B12

fortification

process of adding nutrients to a food; added ones originally not found in the food

indiscriminate fortification can

increase risk of potential nutrient toxicity

percentage of children consuming zinc over recommended UL

45%

enrichment

adding nutrients back to foods that have lost nutrients due to processing

example of enrichment

adding B vitamins to white rice

high temperatures in canning can

reduce nutrient content

fresh produce can be lower in nutrients due to

spending several days on a shelf or in a truck

frozen foods often frozen in the field to

minimize nutrient loss; supplies more vitamins than fresh

dietary supplements

contain combination of vitamins, minerals, herbs, botanicals, AA, enzymes: help some people meets vitamin needs but don’t replace food benefits

fruit and vegetable intake lowers chronic disease but

benefits not duplicated by supplements of nutrients in these foods

if chosen carefully, supplements are

unlikely to be harmful; nutrient intake should not rely heavily on them

most common supplements do not contain

nutrients that population are lacking most

bioavailibility

amount of a nutrient that can be absorbed and utilized in the body

percent of vitamins absorbed in small intestine

40-90%

fat soluble vitamins require ..

fat in the diet to be absorbed; transported in lipoproteins in blood or carrier molecules

water soluble vitamins may require..

energy dependent transport systems or certain molecules in GI tract; transported in blood mostly bound to blood proteins

factors affecting vitamin bioavailability

solubility, energy requiring transport systems, carrier proteins

some vitamins are absorbed in _ forms

inactive provitamin or vitamin precursor forms that must be converted to active forms

digestion of food..

releases vitamins; not digested themselves

vitamin absorption mechanisms depend on

solubility

supplements often provide doses of vitamins..

beyond what we are capable of absorbing

water soluble vitamin storage and excretion

readily excreted from body in the urine, no long term storage besides B12; must be consumed regularly in diet to avoid deficiency

fat soluble vitamins storage and excretion

stored in liver and adipose tissues for longer extent so it takes longer to develop deficiency; excretion is limited so cannot be excreted in urine and toxicity can be an issue

many B vitamins are..

coenzymes

list of B vitamins

B1, B2, B3, biotin, pantothenic acid, B6, folate, B12

B1

thiamin

B2

riboflavin

B3

niacin

thiamin B1

coenzyme for pyruvate dehydrogenase enzyme complex; found mostly in pork

thiamin deficiency

beriberi, wernicke korsakoff syndrome (associated with alcohol abuse)

symptoms of thiamin deficiency

fatigue, depression, anorexia, difficulty breathing

factors affecting thiamin in foods

heat, oxygen, and low acid conditions destroy it; antithiamin factors

antithiamin factors

enzymes that degrade thiamin; raw shellfish, tea, coffee, blueberries, red cabbage

riboflavin is found in

cows milk; light destroys it readily so it’s protected from it in cardboard or opaque plastic containers

riboflavin and niacin function

coenzyme in metabolic reactions to form ATP

riboflavin active coenzyme forms

FAD and FMN

riboflavin deficiency

poor wound or injury healing; affects lining of eyes, mouth, and tongue, skin inflammation

riboflavin deficiency is seen in conjunction with

other B vitamin deficiencies

niacin active coenzyme forms

NAD and NADP

pellegra

niacin deficiency

pellegra early symptoms

fatigue, decreased appetite, indigestion, bright red tongue