Wednesday, January 27, 2010

Tea, Weight Loss, and Control Studies

The Linus Pauling institute at Oregon State University has an outstanding page summarizing recent scientific research on the health effects of tea. This page makes an interesting comment about tea and weight loss:
"It is currently unclear whether tea or tea extracts promote weight loss. Large-scale clinical trials that control for energy intake and expenditure are needed to answer this question."
Are control studies really what we want here?

Western science is based around the idea of controlled studies that isolate one variable and examine the effect of changing that variable when others stay constant. But do controlled studies actually capture what happens in a practical setting? Not at all.

Drinking tea has many mechanisms by which it can influence weight loss through influencing energy intake:

  • Tea is a calorie free drink. Tea can be consumed as a substitute for calorie-rich drinks such as soft drinks, milk, fruit juice, or energy drinks. In this case, drinking tea could directly reduce someone's calorie intake.

  • Tea can be quite bitter, and is generally not very sweet. Drinking unsweetened tea on a regular basis could change people's tastes, making them more accustomed to foods that are less sweet. This could reduce their calorie intake through reducing refined sugars in their diet.

  • Tea contains caffeine, which is known to reduce appetite. Tea also contains a myriad of other chemicals, many of which are poorly understood. It is reasonable that tea could have other effects on appetite and food preferences beyond those caused by caffeine as well. Either way, drinking tea is likely to lead people to reduce their calorie intake overall.

Controlling for energy intake is missing the point. People want to know whether drinking tea will help them lose weight. The vast majority of these people, even those who count calories some of the time, do not effectively control their energy intake the way a scientific study would. People interested in weight loss in the practical setting of their own lives will be more interested in how drinking tea will influence their caloric intake through appetite, food preferences, and any other means. Control studies are missing the point!

Oh, and one last observation--tea extracts do not have the first and second benefit above. Actually drinking tea is necessary to get the full weight-loss potential, since part of the way tea can help you lose weight is through the act of drinking and tasting it, not just through chemicals that you can pop in a pill.

Friday, January 1, 2010

Other Camellias for Tea

The Tea Plant, Camellia sinensis, pictured on the right, is a member of a large genus, Camellia. As with the taxonomy of most species, there are different ideas about how many distinct species there are; the American Camellia Society's page on Camellia Species says that different authorities estimate the number as between 80 and 280...which is a lot.

Few camellias are used for tea other than Camellia sinensis. I found a few sources, including Monrovia's page on Yuletide camellia, that said that the Yuletide camellia, also known as the Christmas Camellia, Camellia sasanqua, is sometimes used to make tea in Japan. Wikipedia also includes this claim, but without giving a source or reference. The same plant is also used to make "tea seed oil". Oil (used for cooking) is also made from Camellia oleifera, and a number of other camellias.

So what about making tea from other camellias?

I am an inherently curious person...I always think of new possibilities, and I admit I am insanely curious about this one. What would it taste like? Granted, it probably wouldn't taste great right off the bad, since the tea plant has been cultivated for hundreds if not thousands of years to yield the beverage we drink today. just seems too obvious a possibility to pass up.

Has anyone done this? Does anyone know anything about this sort of thing?

I'm tempted to try making some tea myself, from Camellias growing here in Delaware...

I guess another philosophical question...would it be tea, or would it be "herbal tea"?

Update: Nigel Melican (teacraftecm on twitter) has informed me that C. irrawadiensis & taliensis, also caffeine-free, make weak "non-commercial liquors". Now I at least want to look into these other species!