Supplements in practice - Vitamin A

Question 1

Oral Vitamin A

Answer 1

Oral vitamin A supplements mainly benefit those with poor or limited diet, or with conditions where there is increased need such as pancreatic disease, eye disease or measles:
* Multivitamin supplements often contain both pro-vitamin A (beta-carotene) and pre-formed vitamin A.
* Retinol acetate or retinyl palmitate (pre-formed vitamin A) —both stable and highly bioavailable.
* Beta-carotene (provitamin A): Most common synthetic form. Converted in body as needed; prevents vitamin A toxicity. Natural form identified on labels, e.g. “from an algal source”.

Question 2

Dosages:

Answer 2

• 750 - 3,000 mcg RAE (2,500–10,000 IU) vitamin A.

Question 3

Caution:

Answer 3

• Not recommended for current or previous smokers (synthetic form especially) —shown to accelerate lung cancer growth. High dietary intake does not have same effect.
• Taking doses greater than 100,000 IU long term may be toxic.
• High dose therapy is only recommended short term; caution with doses over 10,000 IU—especially with liver or renal disease, alcoholism or pregnancy.
• Vitamin A is recycled / stored in the liver; liver toxicity is possible.