B Vitamins Flashcards
The B Vitamins: Coenzymes
Coenzymes: small molecules that work with enzymes to promote their activities
- help the body use energy- yielding nutrients
- B vitamins are components in coenzymes
- help cells multiply
- assist enzymes in performing molecular conversions
Deficiency in Thiamin
Beriberi disease
Deficiency in niacin B vitamin
Pellagra
Thiamin (B1) Function
- critical role in energy metabolism in all cells
- necessary for normal nerve and muscle functioning
Thiamin Deficiency
-Deficiency: Wernicke-Korsakoff syndrome (associated with alcoholism)
S&S: mental confusion, vision problems, coma, hypothermia, low blood pressure, and lack of muscle coordination
Beriberi: (edema or muscle wasting), anorexia and weight loss, neurological disturbances, muscular weakness, heart enlargement and failure
Thiamin deficiency and toxicity
Toxicity: NONE
Thiamin Food Sources
pork, whole grain or enriched bread and cereals; small amounts in nearly all nutritious foods
Riboflavin (B2) Function, Deficiency, in foods, effects of light
Serves as a coenzyme in energy metabolism
- deficiency causes cracks in corners of mouth and sore throat, inflammation of eyelids; sensitivity to light
- no toxicity reported
- foods: milk products; enriched, fortified, or whole-grain products, liver, green vegetables
- effects of light: light sensitive, but heat stable
Niacin (B3) precursor is dietary tryptophan an amino acid
Function: part of coenzymes used in energy production.
Deficiency symptoms: Pellegra (diarrhea, dermatitis, and dementia)
Toxicity symptoms: Niacin flush, liver damage, impaired glucose tolerance)
Food sources: milk, eggs, meat, poultry, fish, whole-grain and enriched breads and cereals, nuts, and all protein-containing foods
- body can produce niacin from tryptophan. UL: 35mg NE
- Niacin (nicotinic acid) used as a medication
Large doses lower blood cholesterol. used in atherosclerosis treatment
Biotin
Function: part of a coenzyme used in energy metabolism
Deficiency Symptoms: Skin, rash, hair loss, neurological disturbances. Intravenous feeding, avidin
Toxicity symptoms: none reported
Food sources: widespread in foods; GI bacteria synthesis
Pantothenic acid
Function: part of a coenzyme used in energy metabolism
Deficiency Symptoms: Digestive and neurological disturbances
Toxicity Symptoms: None reported
Food sources: Widespread in foods
Vitamin B6
Function: Part of coenzymes used in amino acid and fatty acid metabolism. macronutrient metabolism. synthesis of hemoglobin and neurotransmitters. release stored glucose from glycogen.
Deficiency Symptoms: scaly dermatitis, depression, confusion, convulsions, anemia. irritability, weakness
Toxicity: Nerve degeneration, skin lesions (results from supplement use)
Food Sources: meats, fish, poultry, potatoes, legumes, non-citrus fruits, fortified cereals, liver, soy products. heat sensitive
Folate, alcohol, and drugs: negative impact on folate status
- Alcohol: impairs absorption, increases excretion
- Medications: aspirin, oral contraceptives, and anticonvulsants
- smoking
Folate
Function: Activates Vitamin B12 helps synthesize DNA for new cell growth
Deficiency Symptoms: Anemia; smooth, red tongue; mental confusion; elevated homocysteine
Toxicity: masks vitamin B12 deficiency
Food sources: fortified grains, leafy green veg, legumes, seeds, liver
Folate and neural tube defects (NTD)
- prevented by supplements in early pregnancy
- UL: 1000 ug/day from fortified foods and supplements
Vitamin B12
Function: Activates folate; helps synthesize DNA for new cell growth; protects nerve cells
- cell division: accepts carbon groups from folate, regenerating folate’s active form. Macrocytic anemia
- the nervous system: maintains nerve fibers.
Deficiency symptoms: anemia; nerve damage and paralysis
Toxicity: None reported
Foods: foods derived fro animals, fortified cereals (deficiency in vegans)
Absorption: requires intrinsic factor. atrophic gastritis and pernicious anemia
Relationship between folate and vit B12
the term folate refers to two form of the B vitamins: naturally occurring folates in foods and folic acid
- B12 stands by to accept carbon groups from foalte as folate removes them from other compounds. the passing of these carbo groups from folate to vitamin B12 regenerates the active form of folate so that it can continue its dismantling tasks. in the absence of vit B12, folate ist rapped in its inactive metabolically useless form.
- when folate is trapped or there is a deficiency of folate cells that are growing most rapidly (the blood cells) are affected/
