Nutritional Deficiencies: Vitamins

Question 1

Vitamins vs. Minerals

Answer 1

Vitamins

• Essential
• Organic
• Made endogenously

Minerals

• Essential
• Inorganic

Question 2

Risk Factors for Nutritional Deficiency

Answer 2

Inadequate nutrient intake

• Malnutrition from poverty
• Eating disorders or restrictive diets (eg. Fad diets)
• Alcoholism, substance abuse

Increased metabolic needs

• Pregnancy/breastfeeding
• Infants, children during periods of accelerated growth
• Severe trauma/injury, or systemic infection

Malabsorption

• Advanced age
• Celiac disease, cystic fibrosis
• GI disorders: malignancy, prolonged diarrhea, bariatric or other GI surgery

Drug‐Nutrient Interactions

Other

• Social isolation, depression, poor appetite
• Fatigue or arthritis pain affecting food preparation
• Inadequate exposure to sunlight

Question 3

Indications for OTC Vitamins

Answer 3

Prevent deficiencies, replenish stores

OTC vitamin supplements are NOT intended for self‐treatment of deficiencies, unless prescribed by PCP

• No established benefit for healthy individuals to take > Dietary Reference Intake (DRI)
• Once‐daily multivitamin at <100% of DRI sufficient for most
• Refer to PCP for suspected vitamin deficiencies

Question 4

Best strategy to prevent vitamin deficiency..

Answer 4

• eat a balanced and varied diet

Question 5

Fat Soluble Vitamins

Answer 5

Vitamins A,D,E,K (‘The FAT cat lives under ADEK’)
- Can be toxic in excess
- Deficiencies due to limited fat intake or absorption
• Celiac disease, cystic fibrosis, short bowel syndrome
• Certain medications

Question 6

Vitamin A

Answer 6

• Forms: retinoids, carotenoids
• Function: growth/reproduction, skeletal/tooth development, eyes, epithelial cell barrier
• Dietary sources: dark green veggies, red/orange/dark yellow fruits n veggies, egg yolk, liver, milk fat
• Deficiency is rare
• Sx: night blindness, xerophthalmia (cornea dry), dry skin, follicular hyperkeratosis

Question 7

Vitamin A Toxicity

Answer 7

Risk factors

• Doses > DRI
• Retinol > beta‐carotene

‘He Doesn’t Need Vitamin Dosing Very Frequently’
• Headache, diplopia (double vision), nausea, vomiting, drowsiness, vertigo, fatigue
- Carotenemia = yellow skin
- Teratogenic
- Fractures
- Increased risk of lung cancer?

Question 8

Vitamin A Drug Interactions

Answer 8

Ingestion of mineral oil, orlistat, cholestyramine, colestipol

• Decrease vitamin A absorption
• Take multivitamin tablet with vitamin A
• Separate dose by at least 2 hrs before/after dosing

Warfarin

• Large vitamin A doses increases warfarin effect
• Not an issue if vitamin A taken at <= DRI

Question 9

Vitamin D: Toxicity and Interactions

Answer 9

Adverse effects (doses > UL)

• Hypercalcemia
• Anorexia
• Soft‐tissue calcification
• Kidney stones, renal failure

Drug interactions
- Mineral oil, orlistat, cholestyramine: decrease vit D absorption
- Anti‐seizure meds (phenytoin), or prednisone
(glucocorticoid): increase vit D metabolism
• Need higher doses of vitamin D (needs Rx from physician)

Question 10

Vitamin K: AE and Interactions

Answer 10

Adverse Effects

• Changes in dietary vitamin K intake can alter PT/INR
• No toxic effects even at large doses

Drug Interactions

• Orlistat, mineral oil, cholestyramine
• Warfarin (rec consistent amount of vitamin K in diet)
• Broad‐spectrum antibiotics
• Vitamin E (avoid high doses)
• Vitamin A (avoid high doses)

Question 11

B‐Vitamin Supplementation

Answer 11

All B‐vitamins likely need to be supplemented in:

• Inadequate intake
• Malabsorption
• Alcoholics – especially thiamine (vitamin B1)
• Pregnancy/lactation – especially folic acid (vitamin B9)
• Fetal neural tube defects