Green tea is consumed worldwide and contains a plethora of phytochemicals! Most notably the catechins, such as epigallocatechin and epigallocatechin gallate, which may impart health benefits. Indeed, studies in the medical literature have shown that consistent consumption of green tea appear to prevent some cancers, such as those of the upper digestive tract. The antioxidant and polyphenol profile in green tea works to protect against cell and DNA damage through various mechanisms that inhibiting or slow the growth pathways and/or decreasing oxidative damage to our cellular machinery.
Today, as I was drinking a cup of green tea in my office, I ran across a couple articles on green tea and prostate cancer prevention. Although the data is not conclusive, it is suggestive that green tea may have benefits for a cancer that affects 1 in 7 men in the US. First, Jacob and colleagues published a systematic review in the April 2017 issue of the journal Nutrition and Cancer on the impact of chronic green tea consumption and prostate cancer risk by reviewing 15 previously published studies. They found that green tea appeared to decrease prostate cancer development in men at high risk, especially those with high grade pre-cancers.
Guo and colleagues published “Green tea and the risk of prostate cancer: a systematic review and meta-analysis”, in the March 2017 issue of the journal Medicine (Baltimore) titled. Meta-analyses are complex statistical reviews that combines results of several studies to give the overall area of focus more power and credibility.
They found seven observational and three randomized controlled studies that looked for a dose-response association between green tea intake and prostate cancer risk, as well as the preventive effect of green tea catechins on prostate cancer risk. They found a statistical trend of decreased prostate cancer risk with 1 cup/day, and with those consuming more than seven cups daily having a statistically significant reduced risk. Other studies they analyzed that looked at supplementation with extracted green tea catechins showed that these compounds were protective against developing prostate cancer, reducing risk by 62%.
To lend support, an interesting article published in the April 2015 issue of the journal Prostate, looked at men with diagnosed prostate cancer awaiting surgical removal and the effect of green tea, black tea, or water (as a control) on prostate cancer progression and growth. The study authors randomly divided the men into three groups: six cups of brewed green tea daily, six cups of brewed black tea daily, or six cups of water daily. The study lasted about four weeks and over that duration, the researchers measured a variety of blood markers and obtained samples of the prostate cancer tissue removed at surgery to see if there was an influence on the cancer growth. The researchers found that only the green tea decreased inflammation in the cancer tissue and had an antioxidant effect on certain blood markers, including a small decline in blood PSA levels. They also measured tea polyphenol content in tumor specimens from the men and found that 32 out of 34 specimens contained tea polyphenols in the green tea group but none in the black tea group. Although, this does not prove that green tea can be used alone to treat prostate cancer, it is a fascinating study and I applaud the authors and the patients who participated in this study. In my mind, it continues to build the case for green tea consumption for men who have been diagnosed with prostate cancer.
Since this disease is so common, and green tea is widely available and safe, I think that men should seriously consider adding green tea to their daily fluid intake instead of soda or black tea; indeed iced green tea is an ideal drink to have with meals instead of water.
A couple words of caution (sorry it is the chemistry nerd in me) in regards to green tea. First, if you have multiple myeloma and are on the drug Velcade (Bortezomib), do NOT drink green tea, as there is solid evidence that it interferes with the anticancer activity of this drug. Second, green tea also contains vitamin K, so anyone on the blood thinner Coumadin (Warfarin) should avoid drinking green tea as it may decrease the effectiveness of this drug. Data also suggests that large amounts of green tea could interact with the cholesterol medicine Zocor (Simvastatin) and the blood pressure medicine Corgard (Naldolol). Obviously always check with your doctor, but in healthy people green tea is safe and has also been shown to decrease risk of cardiovascular disease and even dental cavities!
Mark A. Marinella, MD, FACP
Phytodense Foods, LLC