Green tea is a popular beverage valued for its high content of antioxidants and polyphenols called catechins. Oral contraceptive pills (OCPs) contain synthetic hormones, typically an estrogen and a progestin, that prevent pregnancy. Since both substances are processed by the body, a common concern is whether the plant compounds in the tea could interfere with the effectiveness of the hormones in the pills. This article reviews the current evidence regarding the safety of combining green tea consumption with oral contraceptives.
How Green Tea Components Interact with Medication
The theoretical basis for a drug interaction lies with the main active compound in green tea, Epigallocatechin gallate (EGCG). EGCG is a catechin that can temporarily influence the body’s drug-processing machinery. This machinery includes a group of liver enzymes, particularly the Cytochrome P450 (CYP) system, which metabolizes many medications, including the hormones found in OCPs.
Laboratory studies, often performed in vitro, have shown that EGCG can inhibit certain CYP enzymes, such as CYP3A4. Inhibition of these enzymes could theoretically slow the breakdown of contraceptive hormones. This slower metabolism could alter the concentration of the hormones in the bloodstream, raising questions about whether their effectiveness could be compromised.
The Evidence on Birth Control Pill Effectiveness
Despite the theoretical mechanism of interaction observed in laboratory settings, human clinical studies offer a much clearer picture. The consensus is that typical consumption of green tea does not compromise the efficacy of oral contraceptive pills. The amount of EGCG absorbed from a standard cup of brewed tea is too low to cause a clinically relevant effect on hormone metabolism.
Pharmacokinetic studies examining the plasma concentrations of contraceptive hormones have found no significant change with moderate green tea intake. A person would need to consume an extremely high amount of green tea, far beyond what is typical, to reach the EGCG concentrations shown to inhibit liver enzymes. For instance, a high dose equivalent to 8 to 16 cups of tea is required to cause a small reduction in CYP3A4 activity.
The only consistently noted interaction involves the caffeine content of green tea, not the hormones themselves. Oral contraceptives slow down the rate at which the body breaks down caffeine. This reduced clearance can result in higher caffeine levels in the blood for a longer duration, potentially leading to increased side effects such as jitteriness, headache, or a fast heartbeat. This effect is independent of the pill’s contraceptive function.
Safe Consumption Practices for Users of Oral Contraceptives
For individuals using oral contraceptives, consuming green tea as a beverage is safe and does not require them to change their contraception regimen. Moderate intake, considered to be about one to three cups daily, is unlikely to affect hormone levels or the pill’s ability to prevent pregnancy.
A clearer risk exists with highly concentrated green tea extract supplements, which contain significantly more EGCG than a beverage. These supplements can deliver hundreds of milligrams of EGCG in a single dose. Individuals taking these high-dose extracts should consult with a healthcare provider to ensure there is no risk of interaction with their medication. Those who choose to consume concentrated extracts should consider separating the time of supplement intake from the time they take their birth control pill by a few hours.