Seemingly every month there is a newly discovered health benefit to drinking tea, often green tea. Shouted from headlines, people sometimes think that they should start drinking tea—specifically green tea—even if they dislike it!
So should they?
Researchers tackle this very question in various ways.
For example, they might first evaluate tea drinkers against a control group.
If those tea drinkers seem to benefit in some way (and plenty of studies indicate there are very real advantages to drinking tea!), the study might evolve into a more controlled experiment within a laboratory setting. After all, the researchers want to isolate what specifically causes the effect and be able to measure it precisely. Then, how might that effect be optimized and applied in a controlled and meaningful way?
Green Tea’s Health Benefits—Physical, Social, Cognitive
Various studies have suggested that drinking green tea may:
- lower the likelihood of dying by stroke, heart attack, or pneumonia
- lower the risk of cognitive impairment (e.g., protect neurons from damage and maintain neuron viability)
- lower risk of depression, psychological distress, osteoporosis, cardiovascular issues
- lower the rate of diabetes, liver disease, body pain
- increase social engagement, motor function, cognitive activity
So just what about tea has these effects? How exactly does this work? Can this factor be isolated, concentrated, and then used medicinally for specific purposes?
The Magic of Polyphenols
A key seems to be polyphenols—antioxidants that are naturally found in plants. All tea—whether green, black, oolong, or white—is produced from Camellia sinensis, and they all have polyphenols. However, these polyphenols differ somewhat.
In Green Tea
When tea leaves are plucked, plant cells are damaged and the leaves immediately begin to oxidize. To stop this process and to produce green tea, the leaves are steamed or pan-fried. This keeps the polyphenols largely as flavanols or catechins. And it is these catechins that give green tea its color and vegetal flavor.
In Black Tea
To produce black tea, the leaves are more fully oxidized, which converts the simple polyphenols into more complex forms: theaflavin and thearubigin. Controlling the oxidation controls the appearance and flavor of black tea, with theaflavin providing the tea’s yellow pigments and bright taste and thearubigin providing tea’s brown pigments and depth of flavor.
But the conversion of catechins into theaflavins does not reduce their antioxidant properties. In fact, one study has shown that green tea catechins and black tea theaflavins have the same antioxidant potency!
And a Magic Ingredient?
In a recent study, one of the polyphenols in green tea, epigallocatechin-3-gallate or EGCG, has been shown to work with the anticoagulant heparin to protect blood vessels against plaque.
In fact, the authors of the study say this is a “surprising cooperative effect of heparin and the green tea polyphenol . . . EGCG” (Townsend et al. 2018).
The EGCG binds to a protein that forms amyloid deposits, and “convert[s] them to smaller soluble molecules that are less likely to be damaging to blood vessels” (GEN 2018).
Upshot? Protection against stroke and heart attack—but, unfortunately, you’re unlikely to get much of this benefit by simply drinking green tea. This is why laboratory experiments are so important, and are designed to potentially bring tea in some form or other into medical treatment options.
So should a person drink tea for its health benefits?
There seems to be few drawbacks to drinking tea (like anything, in moderation) and potentially a lot of benefits, not the least because—well, to many of us, it truly is that magic elixir!
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Genetic Engineering & Biotechnology News (GEN), “Green tea compound dissolves plaques in blood vessels, may boost heart health,” 2018; L. K. Leung et al., “Theaflavins in black tea and catechins in green tea are equally effective antioxidants,” Journal of Nutrition 131(9):2248–51, 2001; Massachusetts General Hospital, “Green tea may help conserve cognition, cup by cup,” Mind, Mood and Memory 8(6):4, 2012; H. Mukhtar and N. Ahmad, “Tea polyphenols,” American Journal of Clinical Nutrition 71(6):1698s–702s, 2000; W. Shen et al., “Tea consumption and cognitive impairment,” PLoS ONE 10(9):e0137781, 2015; Y. Tomata et al., “Green tea consumption and the risk of incident functional disability in elderly Japanese,” American Journal of Clinical Nutrition 95:732–39, 2012; D. Townsend et al., “Epigallocatechin-3-gallate remodels apolipoprotein A-I amyloid fibrils into soluble oligomers in the presence of heparin,” Journal of Biological Chemistry, May 31, 2018; Y. Wang and C.-T. Ho, “Polyphenolic chemistry of tea and coffee,” Journal of Agricultural and Food Chemistry 57:8109–14, 2009.