24: Vitamins

Question 1

Sailors who spent months on a ship developed a condition characterized by exhaustion, bruising, and sore gums/ lost teeth. What was the clinical basis?

Answer 1

Scurvey = vitamin C defficiency

Question 2

Your grandma tells you to eat your carrots or you will lose your sight. What potential vitamin deficiency did she recognize?

Answer 2

Vitamin A defficiency

Question 3

When Popeye needed to eat spinach to gain strength, which vitamin was he supplementing?

Answer 3

Vitamin K

Question 4

Widespread supplementation of this vitamin,

particularly in women of childbearing age is credited with an up to 70% decrease in neural tube defects.

Answer 4

Folate, B9

Question 5

Low serum levels of this vitamin have recently been associated with cancer, particularly colorectal and breast cancer.

Answer 5

Vitamin D

Question 6

Define the term vitamin, & describe features of vitamins.

Answer 6

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.

Question 7

What is DRI, daily reference intake?

Answer 7

DRI: dietary reference intakes—multiple tables that provide a global view of micronutrient requirements and toxic levels

Question 8

What is RDA, recommended daily allowance?

Answer 8

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)

Question 9

Optimal amounts of vitamins & minerals cover a _____.

Answer 9

Optimal amounts of vitamins & minerals cover a range. Optimal amount is between toxicity & deficiency.

Question 10

How do deficiencies arise?

Answer 10

•   Poor nutrition
•   Increased demand (teenagers & lactation)

•  Problem with absorption of one or more
vitamins

•  Interactions with medications

Question 11

What are the lipid & water soluble vitamins?

Answer 11

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

Question 12

Describe Vitamin A function & deficiency

Answer 12

•  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.

Question 13

Describe Vitamin D function & deficiency

Answer 13

•  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

Question 14

Describe Vitamin K function & deficiency

Answer 14

•  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

Question 15

Describe Vitamin E function & deficiency

Answer 15

•  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)

Question 16

Describe Vitamin C function & deficiency

Answer 16

•  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

Question 17

What are the 2 subcategories of B complex vitamins?

Answer 17

Hematopoietic
•  Folate (B9)
•  Cobalamin (B12)

Energy releasing: 
•  Thiamine (B1) 
•  Riboflavin (B2) 
•  Niacin (B3) 
•  Biotin (B7)
•  Pantothenic acid (B5) 
•  Pyridoxine (B6)

Question 18

•   Thiamine = B__?
•   Riboflavin B__?
•   Niacin B__?
•   Pantothenic acid B__?
•   Pyridoxine B__?
•   Biotin B__?
•   Folate B__?
•   Cobalamin B__?

Answer 18

•   Thiamine (B1)
•   Riboflavin (B2)
•   Niacin (B3)
•   Pantothenic acid (B5)
•   Pyridoxine (B6)
•   Biotin (B7)
•   Folate (B9)
•   Cobalamin (B12)

No 4, 8, & 10

Question 19

What are Common effects of deficiencies in

energy-releasing B vitamins?

Answer 19

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.

Question 20

Describe Vitamin B1-Thiamine function & deficiency

Answer 20

•   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

Question 21

Describe Vitamin B2-Riboflavin function & deficiency

Answer 21

•  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.

Question 22

Describe Vitamin B3-Niacin function & deficiency

Answer 22

•  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).

Question 23

Describe Biotin (B7) function & deficiency

Answer 23

•  Function: Coenzyme for several
carboxylases

•  Deficiency: Rare, but can be caused by eating a lot of raw eggs.

Question 24

Describe Pantothenic Acid (Vitamin B5) function & deficiency

Answer 24

•   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

Question 25

Describe Pyridoxine (Vitamin B6) function & deficiency

Answer 25

•   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)