Green Tea Side Effects and Risks

Jitters, Upset Stomach & Other Side Effects

Pot of green tea

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Generally speaking, green tea is a very healthy beverage with numerous benefits. However, in rare cases, some people may experience negative side effects from drinking green tea. These may include nausea, an increased risk of osteoporosis, and more. Find out about these potential risks and how to reduce them.

Caffeine Side Effects

For those with caffeine sensitivity or high consumption levels of green tea, there may be some caffeine side effects. In general, green tea has less caffeine than most other tea types, but some types of green tea, such as matcha, can have more caffeine than your typical black tea or even espresso. Excessive consumption of caffeinated green tea can cause restlessness, heart palpitations, difficulty sleeping, anxiety, irritability, increased heart rate, and elevated blood pressure. People with caffeine sensitivity are more susceptible to these side effects.

You can easily reduce these side effects by drinking less green tea, drinking a different type of green tea, drinking decaf green tea, or brewing your tea less strong. Many people also find that switching from teabags to loose leaf tea makes a big difference in their caffeine jitters. It's worth noting that green tea has a natural chemical called theanine, which has a calming effect on the brain and helps reduce caffeine side effects.

Upset Stomach and Nausea

Like other tea types, green tea contains tannins. Tannins are a naturally occurring chemical which stimulates the stomach to secrete more acid. If you have a peptic ulcer or an acid reflux problem, green tea can cause upset stomach or nausea. If you have diarrhea, tannins can worsen it.

You can reduce or even eliminate this side effect by consuming green tea after a meal or simply when your stomach isn't completely empty. It's also worth noting that green tea is much lower in tannins than most tea types and that it usually causes far fewer stomach problems than coffee.

Iron Deficiency

The tannins in green tea (and other tea types) may prevent the blood from absorbing certain nutrients, particularly non-heme iron. Studies have shown that excessive consumption of green tea may reduce absorption by up to 25 percent.

You can counteract this side effect in a simple and delicious way by adding a slice of lemon to your tea, or by only consuming green tea thirty minutes before or a couple hours after you eat a meal.

Effects During Pregnancy

Green tea is commonly consumed during pregnancy in Japan and China, and it is recognized as being generally safe to drink for pregnant women. Some doctors do advise against consuming any form of caffeine in the early months of pregnancy, since some studies have linked excess intake of caffeine to neural birth defects. To mitigate these potential side effects, you can reduce green tea consumption or select green teas that are lower in caffeine.

Drug Interactions

Like so many other things, green tea can interfere with certain medications. If you have any questions about combining green tea with your medication, consult a doctor or your drug's maker. When in doubt, you can also time your green tea consumption so that it is a few hours before or after when you take your medicine.

Calcium Loss

Some studies show that drinking green tea may increase the amount of calcium that is flushed out of the body with urine. However, it appears that this only occurs in cases where people are consuming more than 400 mg of caffeine (about four to five cups of green tea) per day and that any side effects can be reduced by taking calcium supplements or eating a diet rich in calcium. If you are at risk for osteoporosis, consider reducing your caffeine intake.

Is Drinking Green Tea Worth the Risk?

Green tea's side effects are very rare and are usually only experienced in cases where a person is consuming very large amounts of green tea and already has a medical condition. In general, the health benefits of drinking green tea (especially organic green tea) far outweigh the risks.

If you are experiencing green tea side effects, talk with a doctor and consider reducing the caffeine in your diet.