Teas, such as black tea and green tea, are caffeinated beverages made from the camellia sinensis tea plant. Due to their relatively high caffeine content, teas often have an accelerating effect on the heart rate and can cause palpitations and irregular pulse if you take them in excess. For best results, limit your tea intake to two or three cups a day to stay below the daily recommended 300 mg of caffeine for healthy adults.
Tea and Heart Rate
When tea enters your digestive system, the caffeine is quickly broken down and processed through your bloodstream. Once the caffeine reaches your brain, your central and sympathetic nervous systems become stimulated, resulting in the release of stress hormones such as adrenaline, norepinephrine and cortisol. The release of these stress hormones mimics a natural fight or flight response in the body, resulting in a variety of physical reactions such as accelerated heart rate. As your blood vessels dilate and your breathing begins to intensify, your liver begins releasing glucose into the blood as an instant energy source for your muscles in case of danger.
The Caffeine Effect
Depending on your rate of intake, your hypothalamus, pituitary and adrenal glands may begin releasing stress hormones after as little as 100 to 200 mg of caffeine. Black tea can contain anywhere between 40 and 120 milligrams of caffeine per 8-ounce serving, while some green teas may average 30 to 40 milligrams per 8-ounce serving. As a result, you may begin experiencing symptoms of increased heart rate after drinking two to four cups of tea. Individuals with irregular pulse or heart palpitations are recommended to reduce their caffeine intake in order to help regain a normal heart rate.
Herbal Teas
Herbal teas come in a wide variety and may include blends and other plant mixtures. Although some herbs may have stimulating effects on the cardiovascular system, few studies have been performed on the specific impact of different herbs on heart rate. Unlike teas made from the camellia sinensis plant, herbal teas generally due not contain natural sources of caffeine, and therefore have a less predictable impact on the heart rate.
Safety Concerns
When taken in excess, caffeine can lead to a condition called caffeine overdose that may cause death due to irregular heartbeat. Talk to your doctor if you frequently experience spikes in your heart rate after drinking tea.
References
- MedlinePlus: Black Tea
- Women to Women; Caffeine and The Adrenals - Could They Be Paying Dearly?; Marcelle Pick
- Bigelow Tea; L-Theanine: How a Unique Anxiety Reducer and Mood Enhancer Increases Alpha Waves and Alertness; Carolyn Perrini
- MedlinePlus: Heart Palpitations
- MedlinePlus: Caffeine Overdose
- MayoClinic.com; Caffeine Content For Coffee, Tea, Soda and More; Oct. 3, 2009
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