Tea and Research- Taking a Closer Look Beyond the Headlines

If you subscribe to any newsfeed with ‘tea’ as the keyword, you may be assaulted with a whole list of researching proclaiming the ability of green tea to retard the growth of tumors or some similar health property but in inconclusive language. Then the next week you are subjected to a report that refutes that.

Especially on the internet, our attention span for reading often don’t cross the minute mark and more often than not people skim through headlines and draw their own conclusion.

Unfortunately, this can be rather misleading, at least in the field of tea.

There are thousands of varieties of teas

This seems to be a ‘duh’ statement but tea ranges across a wide-spectrum, even within the same category. And I’m not just referring to taste and prices. Even their nutritional content varies.

Take this USDA database on flavonoids contents of selected foodstuffs for example, for ‘green tea, brewed’ alone (pg 86), the maximum content of Epigallocatechin 3-gallate or EGCG of for short among the products sampled is 203.20 on the index while the minimum is 2.31.

That is almost 100 times difference. Part of the difference is attributable to the tenderness of the leaves, young leaves- bud to 1 leaves- are highest in EGCG. Other possibilities include where it was grown, production methods and so forth.

So when you see headlines that say “Scientists discover that green tea may retard tumor growth’ or ‘Scientists discover there is no clear link between green tea and cancer retardation’, you have to wonder what is the tea used for test and which end of the scale it tethers.

*Note the green tea and cancer headlines are for illustrative purposes only*

The problem is most people other than perhaps tea nerds like me would not be bothered to read beyond the abstract of the medical research. Even if we desired to, access may be restricted, at least free access.

The Devil’s in the Details

An independent tea resource site had an article on storage of tea with this statement:

“A 2009 Ph.D. dissertation study in nutrition found that green tea may stay fresh longer than is widely thought; the study employed a trained tasting panel and tasted green teas from a number of different regions ranging from 3 to 24 months after their original packaging dates. The study found that green tea changes minimally during the first year of storage, and only slightly more during the second year.”

That statement challenged me quite a bit because I knew from experience that wasn’t true. I have thrown away green tea that were 7 or 8 months old because it just didn’t taste like it did when I bought it.

Luckily this journal was freely available online. Fast forward to pg 140 of this report:

“Two Korean commercial loose leaf green teas were chosen as samples….

The samples were packaged in 100 g units in a bag made of metalized multi-layer food grade laminated polyethylene film.  This packaging material serves as an excellent moisture, aroma and oxygen barrier and it has high resistance to chemicals and extreme high or low temperatures.  …. The green tea samples were evaluated at 3, 6, 12, 18, and 24 months.  ….  Three new packages were opened at each storage period for three replications of the test for each storage period. “

The report tested on quite a number of issues and shelf life of green tea was one of them. For the said test, it merely tested on 2 types of Korean green tea- both of them steamed and roasted. Even if you are not a statistician, you would probably agree that a sample size of 2 is scarcely enough to draw a conclusion, especially if both are processed with the essentially same method.

Secondly, it could be used as an argument for the excellence of the packaging material since the seal had not been broken.

Further, let’s take a look at an extract of the journal on its measurement of the taste attribute of green tea.

Attribute  3 mths  6 mths 12 mths 18 mths  24 mths

Green    3.67    3.14    3.14    3.67    3.18

Asparagus    -    -    0.58    0.92    -

Green beans    1.08    1.36    1.83    1.39    1.47

Spinach    1.97    2.36    2.00    1.72    1.79

Brown    1.72    2.42    4.31    2.06      2.77

Ashy/Sooty    -    -    -    -    0.67

Burnt/Scorched    1.44    1.86    2.33    1.58    1.05

Floral/Perfumy    -    -    -    1.19    -

There doesn’t seem to be any ostensible trend to be seen and outliers have been highlighted.

I find it hard to believe any tea could have a floral/perfumy smell emerging out of nowhere and disappearing again, nor asparagus notes for that matter.

Consumption patterns differ across cultures

If you’re relying on population studies, it bears mentioning that consumption patterns of tea vary significantly across cultures.

For example, if you did a study on tea drinkers in Britain and one in Japan, you could easily come away with markedly different conclusions since the former predominantly drink black tea with milk and sugar while the latter are green tea guzzlers.

To accentuate the problem, newspaper headlines are meant to be snappy. You would be likely to see ‘Scottish population studies show that men who consume tea are more likely to be obese than men who don’t’ instead of ‘Scottish population studies show that men who consume tea with milk and sugar are more likely to be obese than men who don’t’

*Above for illustrative purposes only, if you’re of Scottish descent, I apologize’

So the next time you see any research headlines that look shocking, do take a closer look and see the whole context.