Vitamins I and II Flashcards
Nutrients definition
things you need to bring into your body to have normal physiological function
Organic macronutrients
required in large amounts; sources of energy and structural elements; CARBS, FATS, PROTEINS
Micronutrients
required in small amounts; not used for energy or structures; VITAMINS (organic compound), MINERALS (inorganic compounds)
How are micronutrients acquired?
Must be absorbed through diet, body cannot make them
What are the Fat-soluble Vitamins?
A, D, E, K
ADE-K
What are characteristics of Fat-Soluble Vitamins?
ACT LIKE FATS; structure based on isoprene units; uptake is in small intestine along with dietary fats; stored in liver or adipose; transported throughout body in chylomicrons and lipoproteins; deficiencies can arise in people with problems absorbing fats
Large doses of Fat-Soluble Vitamins can be hazardous because…
They are stored. Stored in liver and adipose, can reach toxic levels
In patients with problems digesting fats (problem with pancreas [lipase] or bile production [emulsification])…
They will have trouble absorbing fat-soluble vitamins
What are the Water-Soluble Vitamins?
Niacin Riboflavin Pantothenic Acid Thiamin Folate Vit B12 Vit B6 Biotin Vit C (B Vitamins + C)
Characteristics of Water-Soluble Vitamins?
Taken up by diffusions or mediated transport in small intestine; little storage of these vitamins - excreted in urine; not true for B12
Vitamin B12 is an anomalous water-soluble vitamin because…
does not act like water-soluble vitamin; stored in the body; uptake is different than other WS vitamins
Potential causes for vitamin deficiency in developed countries
- Anorexia
- Bariatric surgery
- Problems with digestion
- Malabsorption (diarrhea, pancreatic problems, small intestine)
- Increased need (pregnancy, lactation, infection)
- Alcoholism (malnutrition or reduced thiamin)
- Smoking (reduces Vit C and E conc)
Why can alcoholics be vitamin deficient?
Can sustain themselves with alcohol because it is high calorically;
Ethanol inhibits absorption of Thiamin;
Ethanol competes with enzymes needed by vitamin A
Common signs of vitamin deficiency
- Dermatitis
- Anemia
- Neuropathy
- Muscle weakness
- Fatigue
- Decreased appetite, growth, immunity
What are the B vitamins?
Thiamin (B1) Riboflavin (B2) Niacin (B3) Pantothenic acid (B5) B6 Biotin Folate B12
(T1R2aiN3)
Coenzyme definition
organic molecule necessary for catalysis (apoenzyme and coenzyme = holoenzyme); required for catalysis, without the coenzyme it does not work
Most common function of vitamins are?
Acting as coenzymes
B vitamin coenzymes
- Niacin - NADH, NADPH
- Riboflavin - FADH2, FMNH2
- Pantothenic acid - CoA, ACP
- Thiamin - thiamin pyrophosphate (TPP)
- Biotin - biotin
- B12 - cobalamin derivatives
- Folate - tetrahydrofolate
B6 - pyridoxal phosphate
Niacin (B3)
Found in grains and meats but often not released during digestion.
Deficiency causes Pellagra (4 D’s - dermatitis, diarrhea, dementia, death).
Diets based on corn can cause Pellagra
Riboflavin (B2)
Part of FAD and FMN; FADH2 formed from breakdown of fuels (TCA, FA oxidation);
FMN - accepts electrons from NADH as a coenzyme in Complex 1 of ETC;
In meat, dairy, dark green veg;
Deficiency isn’t big problem, when deficient it affects tissues of mouth
Pantothenic acid (pantothenate)
Found in all plant and animal based foods;
deficiency extremely rare;
Part of CoA and ACP (contains sulfhydryl group that forms high energy bonds)
Thiamin (B1)
Thiamin pyrophosphate (TPP); TPP is part of PDH and a-ketoglutaric dehydrogenase; found in variety of plant and animal based foods (whole grains have most)
Thiamin deficiency diseases
- alcoholics = Wernicke-Korsakoff Syndrome - combination of Wernicke’s encephalopathy and Korsakoff psychosis;
- chronic defic = Dry beriberi -older adults, wasting/weakness in legs, peripheral neuropathies;
- acute defic = Wet beriberi - edema and heart failure
- infantile beriberi - death from heart failure occurs within hours
Biotin
found in most foods;
deficiency is rare;
coenzyme for ATP-dependent carboxylases;
important for gluconeogenesis and FA synthesis
Vitamin B12 (cobalamin)
Main process B12 is important for is S-adenosylmethionine (SAM) = important for methylation of lipids in myelin;
coenzyme in oxidation of odd-chain FA;
methionine synthesis for homocysteine
Vitamin B12 is found in…
Only found in animal products (comes from bacteria in animals);
Can be stored in live for a significant amount of time;
Vegans/vegetarians can be deficient
Intrinsic Factor
made in parietal cells of stomach; binds B12 in stomach and move together into the intestines and get absorbed together through mediated endocytosis;
No IF = problem absorbing B12
B12 deficiency
can cause anemia and neurological symptoms due to absorption defects (because stomach has been removed, parietal cells fail to make IF, or problems with small intestine);
Pernicious (deadly) anemia - caused by lack of intrinsic factor due to gastritis from autoimmune attack of parietal cells
Folate (folic acid), also found in…
Folate’s active form is tetrahydrofolate (FH4);
important in synthesis of purines, thymine, methionine;
green vegetables, mushrooms
Folate (folic acid) deficiency
Deficiency around the time of conception causes around 50% of neural tube defects;
spina bifida - exposed spinal cord, often some paralysis;
anencephaly - reduced brain tissue;
(fortification of cereal so if a woman got pregnant there wouldn’t be a severe folate deficiency)
T or F: 70% of methyl-tetrahydrofolate in cells needs to be converted by vitamin B12 into its active form
TRUE
Deficiency in either B12 or Folate can cause…
Anemia;
Treatment with folate can overcome anemia from folate or B12 deficiency
Vitamin B6 (pyridoxine)
coenzyme for a lot of enzymes (transfers small groups);
associated with amino acid biosynthesis and catabolism;
needed to make neurotransmitters - serotonin, epi, norepi, GABA
Vitamin K (koagulation)
Green leafy vegetables, made by bacteria in gut;
newborns susceptible to deficiency (given supplement);
Vitamin K (koagulation) coenzymes
coenzymes = phylloquinone, menaquinone;
Vit K dependent carboxylase = allows clotting factors to bind Ca which allows them to bind phospholipids on platelets and endothelial cells
Vitamin K and Warfarin (coumadin)
patients taking warfarin need to maintain a steady amount of vitamin K in diet
Vitamin A (retinol) found in…
Eggs, milk, meat;
B-carotene (provitamin A) is in green, orange, and yellow vegetables and fruits;
Retinoic acid (active form of Vit A)
hormone-like molecule that promotes epithelial differentiation;
important for growth;
deficiency can cause scaly skin and keratinization of cornea
Retinal (Vitamin A)
coenzyme for vision;
in rods and cones, attached to visual pigment protein;
when light hits - G protein activated, phosphodiesterase activated, cGMP decrease, channel closes
Retinal deficiency
most common cause of blindness in the world;
1st night blindness (rhodopsin), corneal damage (keratinization of cornea), blindness
Vitamin D (calcitrol) found in…
fish, egg yolks, fortified milk;
If exposed to enough sun, do not need to acquire through diet
Vitamin D (calcitrol) acts …
Acts as a hormone when low Ca in plasma, causes intestine to absorb calcium, activates osteoclasts (PTH), and causes kidney to increase resorption of calcium (with PTH), binds nuclear vitamin D receptor
Vitamin D (calcitrol) deficiency
lack of UV light and lacking in diet;
rickets (children - softening of bones, bowing of leg bones);
osteomalacia (adults - increased fragility of bones);
deficiency becoming more common (less milk consumption, less exposure to sun
Vitamin C (ascorbic acid) found in…
broccoli, bell peppers, citrus fruit, spinach, tomatoes
Vitamin C (ascorbic acid) acts as
Antioxidant for cytoplasm and interstitial fluid;
Boots many aspects of immune function;
important for maintenance of collagen;
Vitamin C (ascorbic acid) deficiency
Scurvy - capillary fragility due to defective collagen;
bleeding gums, hemorrhages under the skin, joint pain, delayed wound healing
Vitamin E found in
vegetable oils, nuts, animal fats;
deficiency is rare
Vitamin E functions as
antioxidants for lipids; active form a-tocopherol
Dietary reference intakes
EAR - estimated average requirement
RDA - recommended dietary allowance
AI - adequate intake
UL - upper intake level
