24: Vitamins Flashcards
Sailors who spent months on a ship developed a condition characterized by exhaustion, bruising, and sore gums/ lost teeth. What was the clinical basis?
Scurvey = vitamin C defficiency
Your grandma tells you to eat your carrots or you will lose your sight. What potential vitamin deficiency did she recognize?
Vitamin A defficiency
When Popeye needed to eat spinach to gain strength, which vitamin was he supplementing?
Vitamin K
Widespread supplementation of this vitamin,
particularly in women of childbearing age is credited with an up to 70% decrease in neural tube defects.
Folate, B9
Low serum levels of this vitamin have recently been associated with cancer, particularly colorectal and breast cancer.
Vitamin D
Define the term vitamin, & describe features of vitamins.
Vitamins are “a diverse group of organic
molecules required in very small quantities
for health, growth, and survival”
Many vitamins act as co-enzymes;
symptoms of deficiency arise from loss of
enzyme activity.
Vitamins expand the chemistry available in
living systems.
What is DRI, daily reference intake?
DRI: dietary reference intakes—multiple tables that provide a global view of micronutrient requirements and toxic levels
What is RDA, recommended daily allowance?
RDA = recommended daily allowance & it is one component of DRI
It is defined as the amount sufficient to meet the nutrient requirement of 97-98% of healthy individuals in a given group
- -varies for different populations (based on gender, age, etc.)
- -RDAs are reviewed and changed when research warrants it (relatively frequently)
Optimal amounts of vitamins & minerals cover a _____.
Optimal amounts of vitamins & minerals cover a range. Optimal amount is between toxicity & deficiency.
How do deficiencies arise?
- Poor nutrition
- Increased demand (teenagers & lactation)
• Problem with absorption of one or more
vitamins
• Interactions with medications
What are the lipid & water soluble vitamins?
Lipid soluble—Vitamins A, D, K, and E
- -structures resemble lipids so relatively hydrophobic.
- -generally are stored more efficiently in fat than water-soluble.
- -deficiencies don’t arise as quickly
- -toxicity may be a problem (Vit. A and D)
Water soluble = all other vitamins
Water soluble—B vitamins and vitamin C
–more hydrophilic structures
–in general, deficiencies can arise more rapidly
if vitamin is unavailable, since they are excreted
efficiently so less likely to be toxic
Describe Vitamin A function & deficiency
• Functions:
–visual cycle (rhodopsin and cone opsins)
–synthesis of certain glycoproteins and
mucopolysaccharides
–retinoic acid–-acts as hormone
–antioxidant
• Deficiency:
- -night blindness (early signs due to 11 cis retinal issues); xerophthalmia (advanced = corneal ulcers)
- -follicular hyperkeratosis (skin roughening)
- -anemia (despite normal iron intake)
- -poor growth in children
- -increased susceptibility to infection and cancer
Susceptible groups: poor, malnourished; premature babies.
Describe Vitamin D function & deficiency
• Functions:
- -maintaining bone
- -calcium homeostasis
- -acts also as a hormone–receptors are present in many tissues
• Deficiency:
–rickets in children (soft, pliable bones)
–osteomalacia in adults (loss of minerals from bone)
–increased susceptibility to breast and other
cancers, metabolic syndrome/diabetes, and
infection
Susceptible groups: poor, elderly, alcoholics. Other groups may have mild deficiencies
Describe Vitamin K function & deficiency
• Function: localization of enzymes required
for blood clotting (it is a clotting cofactor). Helps catalyze addition of γ-carboxyglutamate to clotting enzymes. It can be given to help counteract bleeding due to anticoagulant properties.
• Deficiency: Results in easy bruising, bleeding, hemorrhage
Susceptible groups:
Newborn infants**, patients on long-term
antibiotics, elderly and others with defects in fat absorption
Describe Vitamin E function & deficiency
• Function:
ANTIOXIDANT—scavenge free radicals
–protect membranes from damage
–prevent oxidation of LDL
• Deficiency: Cardiovascular disease & Neurological symptoms
• Susceptible groups:
Patients with severe, prolonged defects in absorption (ex. celiac disease) or genetic
defects (uncommon)
Describe Vitamin C function & deficiency
• Function:
–cofactor for oxidases involved in collagen
formation
–required for synthesis of steroids in stress
response (response to trauma)
–aids absorption of iron
–has antioxidant activity
• Deficiency:
- -Mild: bruising, immunocompromise
- -Severe: SCURVY (decreased wound healing, osteoporosis, hemorrhage and anemia, fatigue due to decreased collagen). Tooth loss & gum disease in scurvy.
Susceptible groups: people with poor diet,
smokers
What are the 2 subcategories of B complex vitamins?
Hematopoietic
• Folate (B9)
• Cobalamin (B12)
Energy releasing: • Thiamine (B1) • Riboflavin (B2) • Niacin (B3) • Biotin (B7) • Pantothenic acid (B5) • Pyridoxine (B6)
- Thiamine = B__?
- Riboflavin B__?
- Niacin B__?
- Pantothenic acid B__?
- Pyridoxine B__?
- Biotin B__?
- Folate B__?
- Cobalamin B__?
- Thiamine (B1)
- Riboflavin (B2)
- Niacin (B3)
- Pantothenic acid (B5)
- Pyridoxine (B6)
- Biotin (B7)
- Folate (B9)
- Cobalamin (B12)
No 4, 8, & 10
What are Common effects of deficiencies in
energy-releasing B vitamins?
Symptoms show up first in rapidly growing tissues:
Skin—dermatitis
Swollen, red tongue
glossitis
GI—diarrhea
Nervous system also affected because of high
energy demand:
Peripheral neuropathy—tingling of extremities
Depression, confusion
Lack of coordination
Malaise
Different vitamin deficiencies have overlapping
symptoms, but also some distinct features.
Describe Vitamin B1-Thiamine function & deficiency
- Function: Required cofactor for several enzymes in cellular energy metabolism (precursor for TPP which is important in metabolism). Particularly critical in nervous system
- Deficiency:
Mild = GI symptoms, depression, fatigue.
Moderate = Wernike-Korsakoff syndrome in alcoholics—unsteady gait & uncoordinated eye movements.
Severe = Beriberi (people with diet dependent only on polished rice, sometimes alcoholics). Characterized by extreme muscle weakness due to polyneuropathy & leads to heart failure.
Wet beriberi = heart failure gives edema
Describe Vitamin B2-Riboflavin function & deficiency
• Function: Precursor of FAD and FMN, key coenzymes for redox reactions involved in
energy metabolism.
• Deficiency: Ariboflavinosis—rash
around nose, inflammation of mouth and tongue, burning and itchy eyes, light sensitivity
Susceptible groups: Alcoholics, deficiency is quite uncommon.
Describe Vitamin B3-Niacin function & deficiency
• Function: Precursor of NAD and NADP coenzymes important in redox reactions of energy metabolism
• Given to patients with hyper-cholesterolemia or hypertriglyceridemia (high doses).
- Deficiency: Pellagra (piel). Pellagra is classically described by “the four Ds”: diarrhea, dermatitis, dementia and death. Mental symptoms include confusion, memory loss, mania.
- Susceptible groups: People with corn or millet based diets (niacin can be made from tryptophan & corn is trp deficient).
Describe Biotin (B7) function & deficiency
• Function: Coenzyme for several
carboxylases
• Deficiency: Rare, but can be caused by eating a lot of raw eggs.
Describe Pantothenic Acid (Vitamin B5) function & deficiency
- Function: Required for the synthesis of CoA. CoA is a coenzyme for up to 70 different enzymes. Required for TCA cycle and metabolism of all fats and proteins.
- Deficiency: Very rare. Symptoms are typical of B vitamins
Describe Pyridoxine (Vitamin B6) function & deficiency
- Function: Precursor of pyridoxyl phosphate (PLP) enzyme cofactor
- Required for glycogen breakdown,and synthesis of GABA and heme
- Deficiency:
Mild—irritability, nervousness, depression.
Severe = peripheral neuropathy, convulsions, decreased glucose tolerance, hyper homocysteinemia (cardiovascular risk), anemia
• Groups susceptible to deficiency: Patients
treated with certain drugs (isoniazid—TB)
