Turning over a new leaf in 2013: The year tea turned hot...

Peter Goggi, executive VP of the Tea Association of the USA told BeverageDaily.com that recent research in the American Journal of Clinical Nutrition (AJCN) ​on tea's health benefits presents opportunities for tea products including loose leaf, tea bags and RTD teas.

“For example, new Lipton Natural energy takes into he knowledge that theanine and caffeine, naturally found in tea, may have a positive effect on mental performance, including attention and alertness,” ​he added.

In April 2013 Unilever's executive VP of global beverages, Winfried Hopf, described tea as the 'hottest beverage' in global drinks,​ with unlimited opportunities as a natural product having scientifically proven health and wellness benefits.

Tea is the second-most drunk beverage in the world after water, and the December issue of AJCN ​included 12 papers on tea and human health, based on presentations by scientists at the fifth International Scientific Symposium on Tea and Human Health held at the USDA on September 12 2012.

'Significant advance in science of tea' – Professor Jeffrey Blumberg ​

Jeffrey Blumberg, professor at Friedman School of Nutrition Science and Policy, chaired the symposium, and said that the research had “significantly advanced the science of tea and human health”, ​with papers linking tea to a reduced risk of heart disease and certain types of cancer, as well as Type 2 Diabetes.

Peer-reviewed studies in the AJCN ​also concluded that tea has benefits as regards weight loss and maintaining a healthy weight, improving bone health and improving attention, problem solving and mood.

Reflecting on the most striking results from the Arab et al. symposium (it featured 12 speakers, with an additional 26 co-authors of the published proceedings), Blumberg told BeverageDaily.com that he felt the most important outcome was a broad consensus regarding the benefits of tea drinking on heart health and cardiovascular diseases.

“​​However, I personally found the most exciting, new results to be those emerging data suggesting that tea polyphenols may have benefits as well on outcomes such as cognitive function, gut microbiota, and bone health,”​ he added.

On the subject of CVD, Blumberg said that Dr Leonor Arab et al. and colleagues at the University of California, Los Angeles (AJCN​ 2013;98:1651S-9S​), but presented at the 2012 USDA symposium) analyzed five previously published meta-analyses, including 35 observational studies and randomized clinical trials, plus eight recent studies not included in the earlier research.

Blumberg said this meta-analysis revealed a “modest but remarkably consistent” ​benefit of tea in reducing the risk of cardiovascular disease, particularly strokes, in a number of diverse population groups. ​

“Given that cardiovascular disease continues to be one of the major chronic conditions leading to disability and death throughout the world, I feel that consumers can take away the message that when considering their beverage consumption, tea can be an especially healthful choice,” ​he said.

But what would Blumberg say to critics who noted studies linking high tea consumption to prostrate or esophageal cancer or skeletal fluorosis?

Skeletal fluorosis only a risk after excessive consumption​

Jian-Min Yuan from the University of Pittsburgh (AJCN​ 2013;98:1676S–81S​) reviewed 15 observational studies on the relation between green tea and esophageal cancer, Blumberg replied.

Yuan found a significant reduced risk in six studies, a lower risk in four, a null association in two and a significant positive association in just three, and Blumberg said it had long been known that tea at very high temperatures can damage esophageal epithelial cells and stimulate carcinogenesis.

“Earlier systematic reviews show the consumption of any high-temperature beverage – including tea, coffee, and maté – increase the risk of esophageal cancer,” ​he said.

We sent Blumberg a link to an April 2013 article in The Guardian​ newspaper​, which cited an observational study suggesting that tea consumption increased prostate cancer risk, but he said this was not reviewed by Yuan.

"But I note its conclusions are entirely discordant with the vast majority of other studies on this topic,” ​he said.

Turning to skeletal fluorosis, Blumberg admitted that four case reports had been published in US over the past 20 years but said that each patient's behavior had been obsessive compulsive, since they drank one to two gallons of strong tea/day over several decades.

“Excessive, chronic over-consumption of any one food or beverage can lead to nutrient toxicity. However, psychiatric diagnoses and abnormal intakes of tea were not a topic of this symposium,” ​he said.