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