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What are vitamins?
organic compounds with regulatory functions that do not yield energy but contribute to sound nutritional health
What is bioavailability? What influences it?
the rate and extent to which a nutrient is absorbed and utilized. factors include the efficiency of digestion, previous nutrient intake, other foods consumed at same time, method of food preparation, and the source of the nutrient (natural, synthetic or fortified)
Name all the fat-soluble vitamins
A,D, E, and K
Name all the water-soluble vitamins
- B-Vitamins: thiamin, riboflavin, niacin, pantothenic acid, biotin, B6, folate, and B12
- Vitamin C
What is another name for Vitamin C?
Ascorbic acid/ascorbate ion
What is a useful property of Vitamin C?
it can donate and accept hydrogen readily
Describe the absorption of Vitamin C
no digestion is required, absorption is by sodium-dependent transporters, is at 70-90% of usual intakes, and decreases with increased intake
How is Vitamin C transported?
in blood in free form
Where is Vitamin C stored?
cellular uptake is rapid with tissue concentrations higher than plasma. highest concentrations are in the adrenal and pituitary glands, eyes, breain, and WBC's. others include liver, spleen, heart, kidney, lungs, pancreas, and muscle
What groups are at risk of Vitamin C deficiency?
chronic alcohol and drug users, smokers, older adults
What are symptoms of Vitamin C deficiency?
- poor wound healing, gingivitis, inadequate tooth and bone growth/maintenance, increased risk of infection
- extreme cases result in scurvy -- characterized by gingivitis, joint and limb aches, bruising, hemorrhages, plaques, and death
What are the 4 H's of scurvy?
- hemorrhagic signs
- hyperkeratosis of hair follicles (arms, legs, buttocks -- corkscrew hair)
- hypochondriasis (psychological manifestations)
- hematological abnormalities (ruptured sm. blood vessels and bruising)
How is scurvy treated?
100-300 mg/day until gone
What is the UL for Vitamin C and what are symptoms of toxicity?
abddominal pain, osmotic diarrhea, increased risk of calcium oxalate and uric acid kidney stones
What is the RDA and AI for Vitamin C?
What is the relationship between B-vitamins and energy?
contrary to popular belief, they do not provide energy but facilitate the burning of fuel from energy-yielding nutrients
Each of the eight B-vitamins is a ______________?
The active forms of what 5 B-vitamins participate in the release of energy for CHO, AA, and lipids?
Thiamin, Riboflavin, Niacin, Pantothenic Acid, and Biotin
What is the role of Vit. B6 and Vit. B12 in the release of energy?
- B6 assists in AA metabolism
- B12 is required for the development of coenzyme folate which is required for making new cells
What is a Coenzyme?
a small molecule that combines with and enzyme to make it active
What are the main coenzymes of Thiamin (B1) and what are thier biochemical or physiological functions?
- thiamin diphosphate (TDP) and thiamin pyrophosphate (TPP)
- oxidative decarboxylation of alpha-ketoacids and 2-keto sugars
- coenzyme of pyruvate dehydrogenase complex and alpha-ketoglutarate dehydrogennase complex necessary for Kreb's cycle
What noncoenzyme role does thiamin play?
membrane and nerve conduction
What is the deficiency syndrome of thiamin deficiency?
Beriberi (means weakness)
Who is at risk of dry beriberi and what are the symptoms?
- muscle weakness, wasting, peripheral neuropathy
Who is at risk of wet Beriberi and what are the symptoms?
- more extensive than dry Beriberi, includes cardiomegaly, thachycardia, reight side heart failure w/ respiratory involvement, and peripheral edema
Who is at risk of acute Beriberi and what are the symptoms?
- anorexia, vomiting, lactic acidosis, change in heart rate, cardomegaly
What thiamin deficiency is related to alcoholics? What are the symptoms?
- Wernicke-Korsakoff (Wernicke's encephalopathy) -- it is the most common type of thiamin deficiency in developed countries
- paralysis of ocular muscles, nystagmus (constant involuntary eye movement), ataxia (impaired muscle coordination)
What are good food sources of thiamin?
yeast, pork, sunflower seeds, legumes
What is the RDA of thiamin?
- 1.2 mg/day men
- 1.1 mg/day women
- 1.4 mg/day pregnancy
- 1.5 mg day lactation
What destroys thiamin?
heat and alkalinity
What are the main coenzymes of riboflavin (B2) and what are their roles?
- Flavin adenine dinucleotide (FAD and flavin mononucleotide (FMN)
- flavoproteins in the the ET chain and other electron transfer rxns
What is the deficiency syndrome of riboflavin? What are the symptoms?
- cheilosis (painful lesions on lips), glossitis, hyperemia (red/bloody oral cavity) and edema of pharyngeal and oral mucus membranes, angular stomatitis (lesions on corners of mouth), photophobia
What are good food sources of riboflavin?
beef liver, meats, eggs, yogurt, ricotta cheese, and nonfat milk
What is the RDA of riboflavin?
- 1.3 mg/day men
- 1.1 mg/day women
- 1.4 mg/day pregnancy
- 1.6 mg/day lactation
What are risk factors for riboflavin deficiency?
alcoholism, trauma, hypermetabolic conditions
What are other names for niacin?
Vitamin B3, nicotinic acid, nicotinamide
What are the main coenzymes for niacin? What role to they play?
- NAD and NADP
- electron transfer rxns in multiple oxidative rxns (glycolysis, ET chain, pyruvate to acetyl Coa, TCA cycle, fatty acids, pentose phosphate pathway)
What is the deficiency syndrome of niacin? What are the symptoms?
- Pellagra = rough skin
- 4-D's -- dermatitis, diarrhea, dementia, and death
What are side effects with doses of niacin greater than 1 g/day? when might there be large doses?
- flushing, tingling, headaches, heartburn, nausea, vomiting
- large doses used to treat hypercholesterolemia
What is the RDA of niacin?
- 16 mg NE/day men
- 14 mg NE/day women
- 18 mg NE/day pregnancy
- 17 mg NE/day lactation
What are risk factors for pellagra?
alcoholism, malabsorptive conditions, Hartnup disease
What are the main coenzymes of folate and what is their main roles?
- derivatives of tetrahydrofolic acid (THF)
- one-carbon transfer rxns
- AA metabolism
- purine and pyrimidine synthesis/nucleotide metabolism (makes folate essential for DNA synthesis and cell division)
What's the difference between folate and folic acid?
- folic acid is the oxidized form found in fotified foods/supplements
- folate is the reduced form found naturally in foods and tissues
What are good food sources of folate?
brewers' yeast, spinach, asparagus, turnip greens, lima beans, beef liver, fortified grain products
What destroys folate?
heat, oxidation, uv light, processing and prep (raw foods are best source)
What is the deficiency syndrome of folate (besides in utero)? What are the symptoms?
- megaloblastic anemia -- the release of RBC's into circulation that are fewer in number, large, and immature
- diarrhea, fatigue, depression, confusion
What effect does folate deficiency have during pregnancy?
prevention of neural tube defects including spina bifida
What are risk factors for folate deficiency?
alcoholism, malabsorptive conditions, use of certain meds
What is the RDA for folate?
What are main coenzymes for vitamin B12 and what is their role?
- methylcobalamin, adenosylcobalamin
- methylation of homocysteine to methionine
- conversion of methymalnyl-Coa to succinyl-Coa
What storage factor makes B12 different from any other water soluble vitamin?
it can be stored/maintained in body long periods of time -- deficiency may take 3-5 years to develop
What are good food sources of B12?
meat, fish, shellfish, poultry, meat
What is the RDA for B12?
what is the deficiency syndrome of B12 and what are the symptoms?
- megaloblastic anemia
- degeneration of peripheral nerves
What are risk factors of developing B12 deficiency?
elderly, strict vegetarianism, pernicious anemia due to lack of IF, disorders affecting stomach and ileum
What is the main coenzyme of pantothenic acid and what is its role?
- Coenzyme A- CoA
- acyl-transfer rxns
What does pantos mean and what effect does it have on pantothenic acid deficiency
- pantos = everywhere
- pantothenic acid (B5) is found in virtually all plant and animal foods meaning deficiency is unlikely
What is the main coenzyme of biotin and what is its role?
- carboxybiotinyl lysine
- CO2 tranger/carboxylation rxns
What are sources of biotin?
synthesized by microflora of digestive tract, liver, soybeans, eggs
How common is biotin deficiency and what are risk factors? What are the symptoms?
- biotin deficiency is very rare
- risk factors include excessive raw egg ingestion, alchoholism, malabsorptive conditions
What is the main coenzyme of Vitamin B6 and what are its roles?
- pyridoxal phosphate
- transamination and decarboxylation rxns
What are symptoms of B6 deficiency? Who's most at risk?
- dermatitis, glossitis, and convulsions
- elderly, alcoholism, use of certain meds
whats the RDA of B6
What are good food sources of B6?
steak, navy beans, potato, salmon, banana, whole grains
What is the UL of vitamin B6 and what are the symptoms of toxicity?
- 100 mg/day
- sensory and peripheral neuropathy
what is nutrigenetics?
the study of the influence of a nutrient on a risk factor when individual has a variation in genetic code
Name a good example of nutrigenetics.
What form of folate has genetic variations? What chronic diseases does it effect?
- N5, N10 methylenetetrahydrofolate (MHTFR)
- NTDs, CHD, dementias, colorectal cancers