LONDON, United Kingdom
Tea is refreshing. It makes you feel good. It’s healthy…. there is a lot of information and chatter on the internet and we all know it is true – don’t we?
The Food and Drug Administration (FDA) continues to look at the science and rejects proposed health claims (FDA, 2006). The European Food Standards Agency (EFSA) also continues to look at the science and rejects proposed health claims too (EFSA 2008-2011). So what’s the problem? How much science do we have anyway?
The science is now piling up, so how can we make sense of it all. Joe Simrany, president of the Tea Association of the USA, brilliantly started keeping track of progress in his series of International Tea and Health Conferences when we all gathered in New York in March 1991. With four conferences (1991, 1998, 2002, and 2007) now under our belt we have seen a lot of progress.
Tufts University Professor Jeffrey Blumberg reported to us at the 2002 conference that in the five years to 1990 there were fewer than 200 quality checked (peer reviewed) scientific literature articles published on tea and health and in the five years to 2003 there were more than 1,050 (Blumberg, 2003). The published research has increased exponentially since then. We also know much more about polyphenols (flavonoids or antioxidants) in foods; including tea, fruits etc. (USDA, 2007).
We are heading in the right direction.
So it’s good to see Dr. Carrie Ruxton’s update on what has been happening recently in her July article (NHD The Dietitians’ Magazine, 2011).
Her summary reviews 16 studies in the past four years, mainly in relation to heart health, to see how things have moved forward. Having read most of these papers, I can see the accumulating evidence that green and black teas are beneficial to heart health. Three or more cups of tea a day it seems help keep us in the pink.
A couple of large studies in Singapore and Holland provide interesting evidence that drinking black tea can help with reduce risks for diabetes type 2. Cancer is a bit difficult because there are many different types of cancer and many different factors so it is not surprising that we are seeing variable and inconsistent results. There are positive indications, however, we do need more studies that are focused and disciplined to clarify some of the questions. Also, with dental health, similarly, there are certainly positive indications for health benefits but again we need more studies which have been outlined in the reported papers to help give us more certainty.
In addition, this year we have a major achievement with the collaboration of tea scientists across the producer and consumer countries. The American National Standard's Institute standard www.ansil.org for green tea and a revised International Stardard for black tea provide reference materials essential in evaluating the composition of manufactured products.
In Maythe National Institute of Standards and Technology (NIST) released a suite of green tea reference materials to help manufactures evaluate the composition of their products. The reference materials also assure researchers of the accuracy of analytical methods for studying the human health effects of both the beverage and dietary supplements.The new SRMs (Standard Reference Materials) were prepared in collaboration with the National Institutes of Health Office of Dietary Supplements.
These standards include for the first time a minimum polyphenol content; one for green tea and for black tea as well. Tea polyphenols can be measured with internationally verified methods of analysis. This gives much better clarity for the characterization of tea when we put all the science together to describe its contribution to a healthy diet and lifestyle.
We are getting there. However, as a scientist do I have to keep my skeptical hat on when looking at the data. And I will never apologize for that. But, I do love tea. I look forward to every cup, every day.
Dr. Carrie Ruxton (2011), Health Effects of Green and Black Teas, NHD The Dietitians’ Magazine issue 66 (July), pp 12-13
FDA, Food Qualified Health Claims Docket No 2005Q-0297
EFSA Opinions 906 (2008), 1357 (2009), 1463 (2010), 1791 (2010), 2055 (2011), 2058 (2011), 2075 (2011), 2238 (2011)
Blumberg J (2003) J Nutr 133 (10), 3244S-3246S
USDA Database for the flavonoid content of selected foods, Release 2.1 (2007)