Vitamin A and Medication Interaction

Home of Kyle J. Norton for The Better of Living & Living Health Vitamin A also known as Vitamin A Retinol,  is a yellow, fat-soluble substance, and essential for growth and life and producing pigments in the eye’s retina for scotopic vision (low-light vision). The vital vitamin come from 2 types of foods
1. Retinol, one of the animal forms of vitamin A, is a yellow, fat-soluble substance, a diterpenoid and an alcohol converted to vitamin A and and the retinyl ester derivative of the alcohol stored mostly in liver, when eating animal food sources, such as liver and egg yolk. When converted to retinoic acid, vitamin A is essential for skin health, teeth remineralization, bone growth.and the process of cell differentiation, hence, the growth and development of embryos Retinoic acid via the retinoic acid receptor.

2. Carotenes, including alpha-carotene, beta-carotene, gamma-carotene, and
xanthophyl beta- cryptoxanthin, possess the enzyme required to convert these compounds to retinal. Carotenes are the group of orange pigments phytochemical belonging to the class of
Carotenoids (tetraterpenoids), found abundantly in carrots, pumpkins, maize,
tangerine, orange, in dark, leafy greens and red, orange and yellow fruits and vegetables, etc.
and contained many health benefits(1)

Medication interaction
1. Warfarin [Coumadin®], an anticoagulant, increases the risk of abnormal bleeding
when taken with high-dose supplements of fat-soluble vitamins, including vitamin
A. It is recommended to avoid combining vitamin A with warfarin unless
supervised by a physician or pharmacist

2. Bile acid sequestrants such as cholestyramine [Questran®] and colestipol
[Colestid®] are used to lower cholesterol concentrations by preventing
reabsorption of bile acids from the digestive system and by preventing micelle
formation in gastrointestinal (GI) lumen. Since fat-soluble vitamin A requires
the presence of bile for absorption, deficiency may occur if these drugs are
used for a long period of time. During long-term administration of these
medications, it is recommended to take a daily supplement that is a
water-miscible preparation of vitamin A.

3. Oral antibiotics such as neomycin [Mycifradin®] decrease absorption of many
nutrients including vitamin A. People taking antibiotics greater than 10 days
should take multivitamin supplements.

4. Chronic use of laxatives that contain mineral oil can lead to malabsorption of
fat-soluble vitamins, including vitamin A. It is recommended to take the vitamin
two hours before or after mineral oil is used.

5. Retinoid drugs, such as tretinoin [Retin-A®], isotretinoin [Accutane®], and
13-cis as well as all-trans-retinoic acids, are structurally similar to vitamin
A. They are used topically and systemically for the reduction of acne and the
appearance of wrinkles. People using these compounds should avoid vitamin
A-containing supplements due to a possible toxicity.

6. Orlistat [Xenical®], a weight loss GI agent, may decrease GI absorption of
fat-soluble vitamins. In clinical studies, vitamin concentrations during drug
therapy remained within normal range for most patients. Vitamin supplementation
was only occasionally needed. Orlistat and vitamin A supplementation should be
at least 2 hours from each other; fat-soluble vitamins may be taken conveniently
at bedtime.

7. Etc.

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Sources
(1) http://medicaladvisorjournals.blogspot.ca/2012/02/phytochemicals-in-foods-11-health_22.html

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