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What’s in the Tea Leaves?
Two Truths and a Lie About Tea
A warm cup of tea can be a great way to ease into the morning or relax after a long day. Tea is a particularly popular choice for those wishing to cut their caffeine intake or break a coffee habit. If you like the taste – and there are many tastes from which to choose – there’s really no reason not to drink tea. It’s a delightful and flavorful way to stay hydrated with a fair share of healthy properties.
However, there are many well-meaning people who fancy tea to be a magic potion of sorts – it is not. In fact, while tea has few, if any, harmful effects, most claims about the benefits of tea are largely unsubstantiated by research.
To help you get a handle on that cup and saucer, here are two truths and a lie about tea.
Truth: Tea Has Protective Health Properties
When scientists refer to tea, they are referring to processed leaves from the Camellia sinensis plant, which take four primary forms: black tea, green tea, white tea and oolong tea. The distinctions between those derive from how the leaves are treated. Herbal “teas” – ginger, ginseng, hibiscus, jasmine, mint, rooibos and chamomile, among others – are not, technically speaking, teas. They are plant infusions and feature different nutritional characteristics.
But tea, classic Camellia sinensis tea, contains high levels of polyphenol, an antioxidant that is associated with various protective health properties. When scientists study tea, they are mostly studying polyphenol, specifically the antioxidants catechins and epicatechins, and their potential role in preventing cancers, degenerative diseases and cardiovascular conditions. Green tea is the tea most highly concentrated in polyphenol, which is why there are five times as many studies on green tea than black tea.
Truth: The Research is Promising
Most scientists and physicians classify tea research as “promising.” The optimism is drawn from a wealth of what is called meta-analysis, which is a fancy way of saying a study of other studies. This means the conclusions that scientists are comfortable making are drawn from results seen across multiple studies.
Meta-analysis offers considerable support to suggest three to five cups of green tea can lower the risk of ovarian, colorectal, lung and prostate cancer. However, the Academy of Nutrition and Dietetics considers the claim less compelling than others.
The National Institute of Health supports research that one to four cups of black or green tea is linked to lower risks of Parkinson’s disease and some research suggests tea can lower the risk of depression.
Heart health research is the most encouraging. Tea may delay or prevent risk factors of heart disease and lower bad cholesterol, but again, these findings are largely attributed to the effects of antioxidants. Black tea is associated with decreased incidence of heart attack, and green tea with lower bad and higher good cholesterol levels.
The huge caveat to these studies, however, is that they are not drawn from clinical trials with human patients nor do they reflect people who have added tea to their lifestyle with the purpose of getting healthier. Most are observational and therefore are susceptible to a range of confounding factors, such as participants with broad-ranging healthy lifestyle habits.
Lie: The Benefits Are Endless
It’s easy to find a list of health benefits for tea and an accompanying study that supports any range of claim – boosts endurance, protects from UV rays, fights allergies, improves bone density – but most scientists and physicians agree that there’s just not enough evidence to assert these theories with any confidence. Weight loss studies are particularly problematic as they often concern tea extracts and not tea consumption at all.
(It should be added that claims regarding herbal teas – which tend to be of the detox or weight loss variety – have even less research to support them and are widely considered to be unfounded.)
That said, most research suggests that tea has almost no harmful effects. Certain herbal varieties can come with warnings, so be sure to read the labels and consult your primary care physician – particularly if the tea advertises medicinal benefits. And of course, jitters are going to be a risk any time you consume mass quantities of caffeine – so, moderation is everything. But for the most part, if drinking tea helps support your healthy lifestyle, put the kettle on and enjoy your favorite brew with whatever healthy boosts it may or may not include.
source: Northwestern University – Northwestern Medicine