Vitamin A Prophylaxis Dosage for Adults
The recommended prophylactic dose of vitamin A for adults is 6,000 IU daily, which should be included in a routine multivitamin supplement. 1
Recommended Dosing Guidelines
- For healthy adults, vitamin A prophylaxis should be provided as part of a daily multivitamin containing 6,000 IU of vitamin A 1
- For adults who have undergone bariatric surgery (particularly biliopancreatic diversion), a higher prophylactic dose of 10,000 IU vitamin A daily is recommended 1
- For pregnant women or those planning to conceive, the beta-carotene form of vitamin A is preferred over retinol for prophylaxis 1
Special Considerations for Prophylaxis
- Vitamin A is fat-soluble and stored in the liver, which allows for less frequent dosing in some clinical scenarios 2
- When administering vitamin A supplements, they should be given with the lipid emulsion whenever possible to minimize losses due to adsorption and photo-degradation 1
- For adults with specific risk factors for vitamin A deficiency (liver disease, chronic alcohol consumption, short bowel syndrome), more frequent monitoring of vitamin A levels may be necessary while on prophylactic dosing 1
Safety and Upper Limits
- The Institute of Medicine has set the Upper Limit (UL) for vitamin A at 10,000 IU daily for women of childbearing age 1
- Chronic toxicity can result from ingestion of daily amounts exceeding 25,000 IU for more than 6 years or 100,000 IU for more than 6 months 1
- Acute toxicity may develop when quantities above 300,000 IU are ingested within a few hours or days 1
- Daily doses of up to 3 times the recommended daily allowance (approximately 3,000 μg RE or about 10,000 IU) are generally well tolerated without unwanted side effects 3
Treatment of Deficiency (Different from Prophylaxis)
- For treatment of established vitamin A deficiency in adults, higher doses are required: 10,000-25,000 IU daily for 1-2 weeks until clinical improvement 1
- For vitamin A deficiency with corneal changes, more aggressive treatment with 50,000-100,000 IU intramuscularly for 3 days followed by 50,000 IU daily for 2 weeks intramuscularly is recommended 1
- After correction of deficiency, maintenance therapy should return to prophylactic dosing 1
Monitoring
- Serum retinol and retinyl esters measurements should be considered in patients being investigated for malabsorption 1
- Normal serum vitamin A levels for adults range from 300-800 μg/L (1.05-2.8 μmol/L) 1
- In patients with risk factors for deficiency, periodic monitoring of vitamin A levels is recommended 1
Common Pitfalls
- Excessive vitamin A supplementation can exacerbate vitamin K deficiency and affect blood coagulation 1
- Vitamin A is light-sensitive and may undergo photo-degradation, so light-protecting material should be used during administration of parenteral vitamin A 1
- Administering vitamin A with water-soluble solutions can lead to substantial losses; it should be given with lipid emulsion whenever possible 1
- Caution is needed in patients with chronic kidney disease, who may have high retinol serum levels despite potential deficiency in total body stores 1