- The initial T cell response is called a “Th1 response”.
- The secondary B cell antibody response is called a “Th2 response”.
In a healthy body, there is balance between the Th1 (T cell) and Th2 (B cell) parts of our immune system. And that’s the desirable state.
However, sometimes an imbalance of the Th1/Th2 system can be beneficial. For example, during pregnancy women have a tendency to shift towards a Th2 dominance, which is advantageous since a Th1 shift would induce rejection of the fetus.
Autoimmune disease: An immune system out of balance
Virtually all autoimmune diseases -– conditions where the immune system begins to attack self-tissue –- have either a Th1 or a Th2 dominance.
Put another way, autoimmune conditions generally have either a T cell upregulation and B cell suppression (Th1 dominant) or the opposite (Th2 dominant).
It’s imperative that people with autoimmune disorders maintain Th1/Th2 balance.
When the immune system is dysregulated and starts attacking body tissues, the more out of balance the immune system is, the more voraciously it will attack those tissues.
For example, in someone with rheumatoid arthritis, an autoimmune condition where the immune system attacks cartilage, the more out of balance the Th1/Th2 system is, the more cartilage destruction will take place.
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.
Real world example
We had a patient come into our office and report that she took a single antioxidant capsule one night before bed and experienced an array of symptoms including heart palpitations, anxiety, “inward trembling” and insomnia.
The patient had been previously diagnosed with hypothyroidism, a low thyroid condition characterized by weight gain, fatigue, and depression-like symptoms.
The number one cause of hypothyroidism in the United States is an autoimmune condition called Hashimoto’s syndrome (or Hashimoto’s thyroiditis).
The patient’s symptoms after taking the antioxidant indicated an upregulated, or increased attack on her thyroid gland, which then released extra thyroid hormone into her system causing what are classically hyperthyroid symptoms.
When we looked at the ingredients in the antioxidant, it made sense.
Two of the main ingredients –- green tea extract and curcumin -– have been shown to push the immune system towards a Th2 dominance. Given the symptoms she experienced after taking the antioxidant, we concluded that she suffered from a Th2-dominant Hashimoto’s autoimmune condition.
We surmised that the green tea and curcumin stimulated her already lopsided immune system into more aggressively attacking her thyroid gland.
Autoimmunity. Green tea also has immunomodulating effects due to EGCG. Numerous animal studies identify and support the use of EGCG as a potential therapeutic agent in preventing and ameliorating T cell-mediated autoimmune diseases (20). The mechanism involves decreasing T cell activation, proliferation, differentiation, and production of cytokines (20). Of course research on humans demonstrating these effects would be even better, but the animal studies seem promising.
I came across an interesting article by two authors discussing whether green tea can alleviate autoimmune diseases (21). Their observations showed that EGCG is associated with suppressed proliferation of autoreactive T cells, reduced production of proinflammatory cytokines, decreased Th1 and Th17 populations, and increased Treg populations in lymph nodes, spleen and the CNS. What I found interesting is that they converted the doses used on animals, and found out that the average person would need to drink 2.5 liters of green tea per day to receive the same benefits on their immune system. Since this isn’t feasible for most people, they suggested taking EGCG capsules (400 to 2,000 mg/day).
Although I commonly recommend an herbal complex which has a small amount of green tea extract, I haven’t yet tried using higher doses of EGCG on my patients. But after doing research for this article it very well might be something I try out in the future. I still think it’s a good idea to drink one or two cups of green tea per day, but perhaps combining this with EGCG capsules will further help to suppress the autoimmune component of people with Graves’ Disease and Hashimoto’s Thyroiditis. However, one also needs to be cautious, as there is evidence that consuming a concentrated green tea extract can be toxic to the cells of the liver (22). Although this might be rare, it should make us cautious about taking large doses of supplements and herbs.
Can Green Tea Inhibit Thyroid Gland Activity?
There is some evidence which shows that the catechins present in green tea might have antithyroid activity when consumed in high doses (23) (24). However, these studies were performed on rats, and as I just mentioned, involved high doses. I don’t see a problem with most people with hypothyroid conditions drinking one or two cups of green tea per day. On the other hand, people with hypothyroidism and Hashimoto’s Thyroiditis might want to be cautious about drinking larger amounts of green tea on a regular basis.
With the possibility of high doses of green tea inhibiting thyroid activity, some people with hyperthyroid conditions might wonder whether drinking a lot of green tea can help with their condition. I personally haven’t tested this out on my patients, but it would be interesting to find out if drinking a lot of green tea on a daily basis (i.e. five or more cups) would inhibit thyroid activity.
Another potential concern of green tea consumption is that there is fluoride present in green tea. Although the studies I listed attributed the antithyroid activity to the catechins in the green tea, it is also possible that the fluoride was responsible for inhibiting thyroid function. I’m not sure if there is enough fluoride in one or two cups of green tea to have a negative impact on one’s thyroid health, but if you want to play it safe you can purchase green tea that is fluoride-free.
In summary, there are many different health benefits of drinking green tea. As a result, most people can benefit from drinking at least one or two cups per day, and drinking more than this can offer further benefits in preventing the development of certain chronic health conditions. By modulating the immune system, regular green tea consumption can also benefit people with Graves’ Disease and Hashimoto’s Thyroiditis. However, while drinking large amounts of green per day might offer certain benefits (i.e. provide protection against cardiovascular disease), drinking a lot of green tea might have a goitrogenic effect. Although this might be beneficial for those people with hyperthyroidism and Graves’ Disease, those people with hypothyroidism and Hashimoto’s Thyroiditis might want to limit their consumption of green tea to one or two cups per day.