Summary of Interactions with Vitamins, Herbs, & Foods
|May Be Beneficial: Depletion or interference—This medication may deplete these substances from the body or interfere with how they work; extra intake may help replenish them.||
|May Be Beneficial: Side effect reduction and/or prevention—These substances may help reduce the likelihood and/or severity of a potential side effect caused by the medication.||
|May Be Beneficial: Supportive interaction—These substances may help this medication work better.||
|Avoid: Reduces drug effectiveness—When taking this medication, avoid these substances as they may decrease the medication's absorption and/or activity in the body.||
|Avoid: Adverse interaction—When taking this medication, avoid these substances, as the combination may cause undesirable or dangerous interactions.||
St. John’s Wort*
|Check: Explanation needed—When taking this medication, read the article details and discuss them with your doctor or pharmacist before taking these substances.||
Interactions with Vitamins
Oral contraceptive (OC) use can cause folic acid depletion.1 In a double-blind trial of OC users with cervical dysplasia, supplementation with very large amounts (10 mg per day) of folic acid improved cervical health.2 Women with cervical dysplasia diagnosed while they are taking OCs should consult a doctor. Mega-folate supplementation should not be attempted without a doctor’s supervision, nor is there any reason to believe that folic acid supplementation would help people with cervical cancer.
Menstrual blood loss is typically reduced with use of OCs. This can lead to increased iron stores and, presumably, a decreased need for iron in premenopausal women.3 Premenopausal women taking OCs should have their iron levels monitored and talk with their prescribing doctor before using iron-containing supplements.
Women using OCs were found to have significantly lower serum magnesium levels in a controlled study.4 In a preliminary study, blood levels of magnesium decreased in women taking an OC containing ethinyl estradiol and levonorgestrel.5 Although the importance of this interaction remains somewhat unclear, supplementation with 250–350 mg of magnesium per day is a safe and reasonable supplemental level for most adults.
Oral contraceptives have been associated with vitamin B6 depletion and clinical depression. In a small, double-blind study of women with depression taking OCs, vitamin B6 (20 mg twice per day) improved depression.6 Half of the women in the study showed laboratory evidence of vitamin B6 deficiency.
A review of literature suggests that women who use OCs may experience decreased vitamin B1, B2, B3, B12, C, and zinc levels.7 , 8 , 9 OC use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A.10 , 11 , 12 OCs may interfere with manganese absorption.13 The clinical importance of these actions remains unclear.
Interactions with Herbs
Eight cases reported to the Medical Products Agency of Sweden suggest that St. John’s wort may interact with oral contraceptives and cause intramenstrual bleeding and/or changes in menstrual bleeding.14 One reviewer has suggested that St. John’s wort may reduce serum levels of estradiol.15 It should be noted, however, that only three of the eight Swedish women returned to normal menstrual cycles after stopping St. John’s wort. Women taking oral contraceptives for birth control should consult with their doctor before taking St. John’s wort.
Interactions with Foods & Other Compounds
1. Lindenbaum J, Whitehead N, Reyner F. Oral contraceptive hormones, folate metabolism, and the cervical epithelium. Am J Clin Nutr 1975;28:346–53.
2. Butterworth CE Jr, Hatch KD, Gore H, et al. Improvement in cervical dysplasia associated with folic acid therapy in users of oral contraceptives. Am J Clin Nutr 1982 ;35:73–82.
3. Frassinelli-Gunderson EP, Margen S, Brown JR. Iron stores in users of oral contraceptive agents. Am J Clin Nutr 1985;41(4):703.
4. Olatunbosum DA, Adeniyi FA, Adadevoh BK. Effect of oral contraceptives on serum magnesium levels. Int J Fertil 1974;19:224–6.
5. Blum M, Kitai E, Ariel Y, et al. Oral contraceptive lowers serum magnesium. Harefuah 1991;121:363–4 [in Hebrew].
6. Adams PW, Wynn V, Rose DP, et al. Effect of pyridoxine hydrochloride (vitamin B6) upon depression associated with oral contraception. Lancet 1973;I:897–904.
7. Werbach MR. Foundations of Nutritional Medicine. Tarzana, CA: Third Line Press, 1997, 210–1 [review].
8. Wynn V. Vitamins and oral contraceptive use. Lancet 1975;1:561–4.
9. Holt GA. Food & Drug Interaction. Chicago: Precept Press, 1998, 197–8.
10. Werbach MR. Foundations of Nutritional Medicine. Tarzana, CA: Third Line Press, 1997, 210–1 [review].
11. Wynn V. Vitamins and oral contraceptive use. Lancet 1975;1:561–4.
12. Berg G, Kohlmeier L, Brenner H. Effect of oral contraceptive progestins on serum copper concentration. Eur J Clin Nutr 1998;52:711–5.
13. Holt GA. Food & Drug Interaction. Chicago: Precept Press, 1998, 197.
14. Safety of St. John’s wort (Hypericum perforatum)[letters to the editor from various authors]. Lancet 2000;355:575–7.
15. Ernst E. Second thoughts about safety of St. John’s wort [letter]. Lancet 1999;354:2014–6.
16. Threlkeld DS, ed. Hormones, Oral Contraceptives. In Facts and Comparisons Drug Information. St. Louis, MO: Facts and Comparisons, Jul 1994, 107b–8f.
17. Threlkeld DS, ed. Hormones, Oral Contraceptives. In Facts and Comparisons Drug Information. St. Louis, MO: Facts and Comparisons, Jul 1994, 107b–8f.
Last Review: 08-17-2011
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The information presented in Aisle7 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 June 2013.
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