Green Tea helps prevent skin cancer. But what else can it do?
Polyphenols are the active substance in green tea that could help prevent skin cancer, reduce inflammation in tendonitis, and repair DNA in our cells. It sounds like the cup of tea we all need. But does increasing your Polyphenol dosage through food and drink really translate to better health?
Until the late 1990's, when coffee shops started appearing in Northern Ireland, black tea with milk, was the drink of choice in most house-holds. Coffee of-course contains a little more caffeine than tea, which increases our heart rate, resulting in an increased metabolic rate. It also contains some Polyphenols.
Green tea discovery
My interest in green tea began in 2006 when I traveled to live and work in New Zealand, taking up residence initially by the sea in Raglan, a small town famous for its long left-hand point breaks. I wanted to adopt a healthier lifestyle while practicing medicine and improving my surfing. This involved little or no alcohol, running most days, surfing on my weekends-off, and eating lots of raw healthy foods. After meeting a elderly french couple who were staying at the same hostel in Raglan, I entered the green tea chapter of my life.
Image Courtesy of Cole Hutson unsplashed.com
I knew little about green tea before this, other than it was an 'anti-oxidant', could help slow osteoarthritis in mice (Clark et al 2007), and that Japanese people, who seemed very healthy, drank it every day. During my teenage years, I was concerned that I might develop arthritis of some kind, even running was entering the high risk category for developing this disease; although now we know that's not entirely true. But in 2006, arthritis was the least of my worries. The French couple I met, warned me that New Zealand had lost most of its protective stratospheric Ozone Layer which meant I had an increased risk of skin cancer if I spent a lot of time outside. Quite directly, they stated that sun-screens did not offer enough protection, and in some cases could be harmful, so they recommended that I start drinking green tea; so I did. I continued to wear my factor-55 zinc sunblock, but consciously made sure I was consuming 2-3 cups of green tea a day to prevent UV-radiation damage. I took my tea drinking and healthy habits with me when I left New Zealand, along with my cultivated addiction to surfing. But you can have too much of good thing, as I later discovered.
Tendonitis
Five years later, having lost some of my green tea infatuation, I had shoulder surgery for a fracture and tendon over-use injury. Despite my best efforts at physiotherapy, the recovery was slow and I developed persistent tendonitis in the shoulder muscles, which wouldn't go away. I had heard about a physiotherapist, named Professor Jill Cook from Australia, who was using green tea three times a day as part of her treatment for tendonitis, along with an antibiotic known for its anti-inflammatory properties (Cook et al.2002, Fallon et al. 2008). As I had occasional fleeting tendonitis throughout my sporting life, and a family history of inflammatory arthritis, I was hoping that upping my green tea intake might also stave off any looming inflammatory arthritis. So, I resumed my green tea affair with gusto!
I noticed that green tea reduced my intermittent pain to almost zero. Coffee, on the other hand seemed to make it worse, as did feeling stressed. This, of course is anecdotal evidence that green tea may improve perceived or real pain from inflamed tendons; however, there are rodent studies showing its benefit in tendonitis and inflammatory bowel disease. The study on tendonitis prepared the green tea with water at 80degrees Celsius, soaking it for 20 minutes (Vieira et al. 2015), and the inflammatory bowel disease study used green tea Polyphenol extract at low to high doses, without specifying exact concentrations (Oz et al.2013). Because these are animal studies they do not provide evidence that the same will occur in humans. But time will tell.
When I see a patient with any type of tendonitis, I recommend regular eccentric and core strengthening exercises (with a physiotherapist initially), along with organising a full bio-mechanical assessment. But I also suggest the introduction of green tea to their diet. It doesn't agree with everyone, and if you have acid reflux in the esophagus the caffeine in tea can make it worse.
Tendonitis is unpredictable and pain pathways can persist even when active inflammation of the tendon has stopped, so green tea provides a useful option when running out treatment ideas.
Skin Cancer
There are natural sunblocks such as Zinc oxide, and substances that contain natural SPF's like coconut oil, but what if we could enhance these effects by drinking tea?
Sunshine can activate inflammation in the skin, which can affect the whole body as seen in Lupus, where sun exposure often causes a flare-up of the disease. It is the polyphenol in green tea that helps reduce the affects of the sun's UV rays on our cells. UV-b rays cause damage to the DNA in our cells, thus reducing our immune system's ability to repair this 'damage'. Our body tries to repair this damage but sometimes it does not succeed and the result is the growth of cancer cells ( Bidlack & Rodrigeuz 2012). Most studies have been performed in rodents, however there is one study using Green Tea Polyphenols applied to the skin of humans, which showed a reduction in products that cause DNA damage (Katiyar et al. 2000).
“It is estimated that on average we would need to drink 5-6 cups of green tea a day to gain sufficient protection from UV-b radiation.”
Conclusion
Although 5-6 cups of tea contains too much caffeine for most people, 2-3 cups a day may confer some benefit to overall health.
If you are pregnant you should limit your caffeine intake to 1-2 cups of green tea a day.
Making decisions to change what we eat and drink can be challenging. If you are on the fence about whether to swap your coffee for green tea, think about its potential benefits against UV-b radiation, and its general anti-inflammatory affects as seen in rodent studies. Green tea may even improve your cholesterol profile (Kim et al.2011) and help with any niggling tendonitis (Cook et el. 2002).
You can learn more about Polyphenols found in Red wine and turmeric here.
References
Clark KL. Nutritional considerations in joint health. Clinical Sports Medicine 2007;26:101–18.
COOK, J. L., KHAN, K. M. & PURDAM, C. 2002. Achilles tendinopathy. Manual Therapy, 7, 121-130.
FALLON, K., PURDAM, C., COOK, J. & LOVELL, G. 2008. A "polypill" for acute tendon pain in athletes with tendinopathy? J Sci Med Sport, 11, 235-8.
KIM, A., CHIU, A., BARONE, M. K., AVINO, D., WANG, F., COLEMAN, C. I. & PHUNG, O. J. 2011. Green tea catechins decrease total and low-density lipoprotein cholesterol: a systematic review and meta-analysis. J Am Diet Assoc, 111, 1720-9.
OZ, H. S., CHEN, T. & DE VILLIERS, W. J. 2013. Green Tea Polyphenols and Sulfasalazine have Parallel Anti-Inflammatory Properties in Colitis Models. Front Immunol, 4, 132.
W.R Bidlack & R.L. Rodriguez. Nutritional Genomics: the Impact of Dietary Regulation of Gene Function on Human Disease. 2012 by Taylor and Francis Group
C. P. Vieira, F. Da Ré Guerra, L. P. de Oliveira, M. S. Almeida, Maria Cristina Cintra Marcondes & E. R. Pimentell (2015) Green tea and glycine aid in the recovery of tendinitis of the Achilles tendon of rats, Connective Tissue Research, 56:1, 50-58, DOI: 10.3109/03008207.2014.983270