Folate
Effect: Supplementation Possibly Helpful
Although the evidence is not consistent, women who are taking oral contraceptives
(OCs) may need extra folate. Because folate deficiency is
fairly common, even among women who are not taking OCs, and because the body
should not lack an essential nutrient, taking a folate supplement on general
principle is a good idea.
Other Nutrients
Effect: Supplementation Possibly Helpful
Evidence from several studies suggests that OCs might interfere with the absorption or metabolism of magnesium, vitamin B2, vitamin C, and zinc. With the exception of the trials involving magnesium, these studies used older, high-dose OCs. Modern, low-dose OCs may not affect nutrients to the same extent.
St. John’s Wort
Effect: Decreased Effectiveness of Drug
Reliable case reports, as well as controlled clinical trials, indicate that
St. John’s
wort interferes with the effectiveness of oral contraceptives
and may have led to unwanted pregnancies.
Indole-3-Carbinol
Effect: Possible Reduced Effectiveness of Drug
Indole-3-carbinol
(I3C) is a substance found in broccoli that is thought to
have cancer-preventive effects. One of its mechanisms of action is thought to
involve facilitating the inactivation of estrogen, as well as blocking its effects
on cells. The net result could be decreased effectiveness of oral
contraceptives.
Dong Quai, St. John’s Wort
Effect: Possible Harmful Interaction
OCs have been reported to cause increased sensitivity to the sun, amplifying the
risk of sunburn or skin rash. Because dong quai and St. John’s wort may also
cause this problem, taking these herbal supplements while taking OCs might add to
this risk. It may be a good idea to wear sunscreen or protective clothing during
sun exposure if one takes one of these herbs while using OCs.
Rosemary
Effect: Possible Harmful Interaction
Weak evidence hints that the herb rosemary may enhance the liver’s
ability to deactivate estrogen in the body. This could potentially interfere with
the activity of medications that contain estrogen.
Grapefruit Juice
Effect: Possible Harmful Interaction
Grapefruit juice slows the body’s normal breakdown of several drugs, including estrogen, allowing it to build up to potentially excessive levels in the blood. A recent study indicates this effect can last for three days or more following the last glass of juice. If one takes estrogen, the safest approach is to avoid grapefruit juice altogether.
Resveratrol
Effect: Possible Harmful Interaction
The supplement resveratrol has a chemical structure similar to that of the
synthetic estrogen diethylstilbestrol and produces estrogenic-like effects. For
this reason, it should not be combined with prescription estrogen products.
Milk Thistle
Effect: Possible Decreased Action of Drug
One report has noted that an ingredient of milk thistle,
silibinin, can inhibit a bacterial enzyme called beta-glucuronidase. This enzyme
helps oral contraceptives work. Taking milk thistle could, therefore, reduce the
effectiveness of OCs.
Androstenedione
Effect: Theoretical Harmful Interaction
Androstenedione has become popular as a sports supplement,
on the theory that it increases testosterone levels, as well as sports
performance. However, there is no evidence that it is effective. In addition,
androstenedione appears more likely to elevate estrogen than testosterone levels.
This could increase risks of developing estrogen-related diseases, including
breast and uterine cancers. Women taking estrogen should not take
androstenedione.
Soy
Effect: Probably No Interaction
Fears have been expressed by some experts that soy or soy
isoflavones might interfere with the action of oral
contraceptives. However, one study of thity-six women suggests that such concerns
are groundless.
Bibliography
Bradlow, H. L., et al. “Multifunctional Aspects of the Action of Indole-3-Carbinol as an Antitumor Agent.” Annals of the New York Academy of Sciences 889 (1999): 204-13.
Jobst, K. A., et al. “Safety of St. John’s Wort (Hypericum perforatum).” The Lancet 355 (2000): 575.
Martini, M. C., et al. “Effects of Soy Intake on Sex Hormone Metabolism in Premenopausal Women.” Nutrition and Cancer 34 (1999): 133-139.
Meng, Q., et al. “Indole-3-Carbinol Is a Negative Regulator of Estrogen Receptor-Alpha Signaling in Human Tumor Cells.” Journal of Nutrition 130 (2000): 2927-2931.
Michnovicz, J. J. “Increased Estrogen 2-Hydroxylation in Obese Women Using Oral Indole-3-Carbinol.” International Journal of Obesity and Related Metabolic Disorders 22 (1998): 227-229.
Pfrunder, A., et al. “Interaction of St. John’s Wort with Low-Dose Oral Contraceptive Therapy.” British Journal of Clinical Pharmacology 56 (2003): 683-690.
Takanaga, H., et al. “Relationship Between Time After Intake of Grapefruit Juice and the Effect on Pharmacokinetics and Pharmacodynamics of Nisoldipine in Healthy Subjects.” Clinical Pharmacology and Therapeutics 67 (2000): 201-214.
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