Vitamin A

Question 1

Who mainly benefits from oral vitamin A supplements?

Answer 1

People with poor or limited diets, or with increased needs (e.g., pancreatic disease, eye disease, measles).

Question 2

What forms of vitamin A are commonly found in multivitamins?

Answer 2

Provitamin A (beta-carotene) and pre-formed vitamin A (retinol acetate or retinyl palmitate).

Question 3

What are retinol acetate and retinyl palmitate?

Answer 3

Stable, highly bioavailable forms of pre-formed vitamin A.

Question 4

What is beta-carotene?

Answer 4

The most common synthetic form of provitamin A that is converted by the body as needed and helps prevent vitamin A toxicity.

Question 5

What is the typical dosage range for vitamin A supplementation?

Answer 5

750–3,000 mcg RAE (2,500–10,000 IU).

Question 6

Why should vitamin A supplements be avoided by current or former smokers?

Answer 6

Synthetic vitamin A has been shown to accelerate lung cancer growth in smokers.

Question 7

What are the risks of long-term high-dose vitamin A supplementation?

Answer 7

Toxicity, especially at doses greater than 100,000 IU, and possible liver toxicity.

Question 8

What precautions should be taken when dosing vitamin A?

Answer 8

Avoid doses over 10,000 IU long term, especially with liver/renal disease, alcoholism, or pregnancy.