Balancing the Health Benefits of Green Tea with Its Side Effects

Tea is one of the most consumed drinks in the world. While black and white tea are popular, studies have focused on the health benefits of green tea mainly because of the belief that the most significant health benefits can be derived from the consumption of green tea.

Health Benefits of Green Tea

A popular use of green tea is in cancer prevention. Studies of certain populations show lower rates of cancer in Japan where green tea is regularly consumed although a causal relationship is difficult to establish for now. Women who regularly drink green tea may have a significantly lower risk of developing ovarian cancer than women who do not.

Another commonly espoused health benefit of green tea is its effect on fat metabolism. Several studies done on adults showed that green tea may cause significantly weight loss if it is combined with moderate exercise or caffeine. A 2008 study by Matsuyama et al on obese children showed that green tea significantly reduced the waist circumference, LDL cholesterol and blood pressure after ingestion of green tea for 24 weeks.

How Much Green Tea is too Much?

More than five cups of green tea is considered too much. It can cause side effects due to the caffeine content and these may range from mild to serious, including headache, sleep problems, irregular or rapid heartbeat, tremors, confusion and convulsions.

For consumers wanting to maximize the health benefits of green tea, experts recommend that they should see a doctor first especially if they have pre-existing medical conditions or taking other medications. Green tea may reduce iron absorption so patients with iron-deficiency anemia should not take so much of it.

For pregnant or breastfeeding women, experts recommend that they take no more than two cups of green tea. This provides approximately 200mg of caffeine. Taking more than this amount has been associated with a higher risk of miscarriage. Caffeine is also expressed in breast milk and may overstimulate the baby.

Green tea may also interact with some drugs. For example, oral contraceptive pills and certain antibiotics may slow down the metabolism of caffeine, leading to unwanted side effects. Green tea may also slow the blood clotting process so if it is combined with drugs like aspirin or warfarin, the patient may experience easy bruising and bleeding.

Some studies also show that green tea may be toxic to the liver. Patients may complain of yellowing of the eyes and skin together with right upper quadrant abdominal pain. The mechanism of injury is not yet clear. Some researchers suggest that given how sporadic these cases of liver damage were, it might even be an allergic response to the tea and not really due to the catechins themselves. Recent researches like those of Matsuyama et al and Shen et al in 2010 failed to demonstrate adverse effects after intake of green tea for 24 weeks. However, the current recommendation is that despite the proven health benefits of green tea, all tea supplements should carry labels that it should not be taken on an empty stomach.