Friday, January 02, 2009

Research Review: Could Green Tea Actually Be Bad For YOU?

Precision Nutrition (Dr. John Berardi's website) has posted an interesting (and somewhat alarming) article on the possible downside of green tea as a wonder supplement. I hadn't seen this research before, so I thought it important to pass it along.

Research Review: Could Green Tea Actually Be Bad For YOU?

Should you banish this harmless-looking substance from your pantry?

Friend or foe?

Green tea has received a lot of positive media attention in recent years. But is it really good for everyone?

Not necessarily.

There is a group of people for whom green tea may be hazardous. And given green tea’s popularity these days, it’s critical to share this information with anyone interested in health.

Green tea has a wealth of research behind it demonstrating a number of health-promoting benefits including anti-inflammatory, anti-carcinogenic and antioxidant properties. Many of green tea’s benefits are due to its effects on the immune system, which is also where it can cause problems.

But before telling you how green tea impacts the immune system, let’s take a quick look at a simplified version of how it works.

Here is the main point, although you should read the whole article.

When healthy foods are unhealthy

According to research, a number of natural compounds have a tendency to push either side of the Th1/Th2 balance. Green tea is one such substance. The active components of green tea have a tendency to push the Th2 system to be more dominant by inhibiting the Th1 side of the immune system. Therefore someone with a Th2-dominant autoimmune condition (see table below) would be wise to stay away from green tea or products containing concentrated green tea (such as a green tea supplement), because it can upregulate an already dominant system and lead to more tissue destruction. Conversely in someone with a Th1-dominant autoimmune condition, green tea would be beneficial because it inhibits the Th1 side of the immune system.

Another common example most people know of is the herb echinacea. When people get sick with a cold or flu, echinacea helps boost the T cells (Th1 response) involved with the initial attack of a foreign invader. However, in a Th1-dominant autoimmune condition, echinacea will likely make the condition worse and is therefore be something to be avoided.

The more we know, the better we can pinpoint which supplements are going to be beneficial - this is some important research that will hopefully lead to more and better studies on how best to protect ourselves from various diseases.

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