Also indexed as: Xenical®
Orlistat is used for obesity management, including
weight loss and weight maintenance, in association with a low-calorie diet.
Summary of
Interactions with Vitamins, Herbs, and Foods
In some cases, an herb or supplement may appear in more than one category, which may seem
contradictory. For clarification, read the full article for details about the summarized
interactions.
 May be Beneficial: Depletion or
interference—The medication may deplete or interfere with the absorption or
function of the nutrient. Taking these nutrients may help replenish them. |
Beta-carotene
Vitamin A
Vitamin D
Vitamin E
|
| May be Beneficial: Side effect
reduction/prevention—Taking these supplements may help reduce the likelihood and/or
severity of a potential side effect caused by the medication. |
Psyllium
|
| May be Beneficial: Supportive
interaction—Taking these supplements may support or otherwise help your medication
work better. |
Food
|
| Reduced drug
absorption/bioavailability |
None known
|
| Adverse interaction |
None known
|
An asterisk (*) next to an item in the summary indicates that the
interaction is supported only by weak, fragmentary, and/or contradictory scientific
evidence.
Interactions with Dietary Supplements
Beta-carotene
One well-controlled study showed that taking orlistat greatly reduces the absorption of
beta-carotene.1 Therefore, individuals taking orlistat for long periods of time
should probably supplement with beta-carotene.
Vitamin E
Taking orlistat dramatically reduces the absorption of vitamin E,2 which might
result in deficiency symptoms. Therefore, people taking orlistat for long periods of time
should supplement with vitamin E.
Vitamin A and Vitamin D
In one well-controlled study, taking orlistat for six months resulted in reduced blood levels
of vitamins A and D, though levels for most individuals remained within the normal range.
However, a few people developed levels low enough to require supplementation.3
Other studies have shown that taking orlistat had no affect on blood vitamin A
levels.4 5 Although additional research is needed, the current evidence
suggests that individuals taking orlistat for more than six months should supplement with
vitamins A and D.
Interactions with Herbs
Psyllium
In a group of obese women taking orlistat three times per day, ingestion of 6 grams of
psyllium with each dose of orlistat significantly reduced the gastrointestinal side effects of
the drug.6
Interactions with Foods and Other Compounds
Food
Orlistat blocks enzymes responsible for the breakdown and absorption of fat. Therefore,
orlistat should be taken during, or up to one hour after, each main meal that contains
fat.7
References
1. Zhi J, Melia AT, Koss-Twardy SG, et al. The effect of orlistat, an
inhibitor of dietary fat absorption, on the pharmacokinetics of beta-carotene in healthy
volunteers. J Clin Pharmacol 1996;36:152–9.
2. Sifton DW, ed. Physicians’ Desk Reference. Montvale,
NJ: Medical Economics Company, Inc., 2000, 2693–6.
3. Van Gaal LF, Broom JI, Enzi G, Toplak H. Efficacy and tolerability of
orlistat in the treatment of obesity: a 6-month dose ranging study. Orlistat Dose-Ranging
Study Group. Eur J Clin Pharmacol 1998;54:125–32.
4. Melia AT, Koss-Twardy SG, Zhi J. The effect of orlistat, an inhibitor
of dietary fat absorption, on the absorption of vitamins A and E in healthy volunteers. J Clin
Pharmacol 1996;36:647–53.
5. James WP, Aveell A, Broom J, Whitehead J. A one-year trial to assess
the value of orlistat in the management of obesity. Int J Obes Relat Metab Disord
1997;21 Suppl 3:S24–30.
6. Cavaliere H, Floriano I, Medeiros-Neto G. Gastrointestinal side
effects of orlistat may be prevented by concomitant prescription of natural fibers (psyllium
mucilloid). Int J Obes Relat Metab Disord 2001;25:1095–9.
7. Sifton DW, ed. Physicians’ Desk Reference. Montvale,
NJ: Medical Economics Company, Inc., 2000, 2693–6.
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Learn more about the authors of Using
Medicines with Vitamins and Herbs
The information presented in Healthnotes is for informational
purposes only. It is based on scientific studies (human, animal, or in vitro),
clinical experience, or traditional usage as cited in each article. The results reported may
not necessarily occur in all individuals. For many of the conditions discussed, treatment with
prescription or over-the-counter medication is also available. Consult your doctor,
practitioner, and/or pharmacist for any health problem and before using any supplements or
before making any changes in prescribed medications. Information expires December 2005.