why does black tea effect me so

October 7, 2006 6:43 AM

why does black tea effect me so?

everytime i drink black tea i lose all tiredness, even if i've been awake for over 24 hours or more and my focus increases dramaticlly. coffee, cocoa and green tea don't have this effect. why does only black tea do this, especially plain black tea?

posted by randomizer to health (5 comments total)

I'm going with Wiki:

Black tea is a "true" tea (i.e. Camellia sinensis) made from leaves more heavily oxidized than the white, green, and oolong varieties. Black tea is generally stronger in flavor and contains more caffeine than the more lightly oxidized teas.

posted by disillusioned at 6:53 AM on October 7, 2006

"Caffeine is present in tea leaves and in coffee to the extent of about 4%. Tea also contains two other alkaloids, theobromine and theophylline. These last two relax the smooth muscles where caffeine stimulates the heart and respiratory systems." from here
If I remember right theophylline used to be an active ingredient in asthma drugs, and it made the kid nervous. It's not the caffeine, it's the other stimulants, and they're pretty strong ones.
posted by unrepentanthippie at 7:47 AM on October 7, 2006 [1 favorite]

When you add milk to tea the calcium chelates and binds up a lot of the tannins (those active ingredients unrepentanthippie is talking about), so this explains why plain black tea is more potent in your case. It also explains why it's pointless and silly to use fancy calcium-enriched milk in your morning cup of tea.

Different people have different capacity to metabolise/react to secondary metabolites from plants, it seems your biochemistry is particularly sensitive to the non-caffeine stimulant effects of black tea.
posted by shelleycat at 1:27 PM on October 7, 2006

Tannins are phenolic compounds, not alkaloids like caffeine or theophylline. Neither the milk, nor calcium by itself, has any effect on the stimulant bioavailability of tea that I'm aware of. Randomizer probably has adenosine receptors that are more sensitive to the alkaloids found in black tea. I get the same effect.
posted by Mr. Gunn at 6:41 PM on October 8, 2006

Adding calcium to black tea does interact with polyphenols and other active compounds (caffeine, theaflavin, etc) in black tea, encouraging them to clump together and come out of solution (1). It's a process that happens anyway but increasing calcium levels drives the process. Calcium biovailability from tea is also low (2), probably due to the polyphenol interaction.

Interestingly, the paper I remembered this from initially put forward the idea that calcium binding up polyphenols would reduce putative anti-cancer properties of black tea. Whereas later research (3) indicates that this isn't the case, and other other research also supports the idea that adding milk does not interfere with bioavailability/bioactivity of the tannins despite the chemical interaction (4, 5).

For someone relatively sensitive to the bioactive compounds in tea (alkaloid, polyphenol, whatever), as the original poster appears to be, it is still plausible that lowering concentration of these soluble compounds by adding milk has a noticable effect which would not be seen in someone else (particularly given traditonal nutrition studies generally don't take individual variation into account). However, a quick scan of the current research indicates that adding milk makes no difference and I'm probably wrong about that part.
posted by shelleycat at 11:22 PM on October 8, 2006