|Image 1: Though color does matter to some extend, the most important thing appears to be that you drink your tea, whether it is green, black, white or well... pu-erh ;-)|
Tea in lieu of hot wine punch could ward off your holiday weight gain
In their 12-week study, Hsiu-Chen Huang and Jen-Kun Lin fed a group of initially healthy five-weeks-old male wistar rats (body weight: 150-200g) either a standard rat chow (Purina, Ralston Purina, St. Louis, MO) or a chow that consisted of 60% fructose and 40% of the chow. Now, the latter group was again divided into a fructose control group and 4 experimental groups, where 4% of the standard chow were replaced by ground green, oolong, black or pu-erh tea leaves.
|Figure 1: Catechin content of the leaves of green, oolong, black and pu-erh tea.|
If we do yet assume that the main effect is induced by the "active ingredients" of the leaves and take the catechin content as a measure of how much of that we would have to ingest, eating the whole leaves is probably not even necessary. With their daily food intake of ~27.5g the rodents got roughly 46mg of catechins (calculated for the green tea).
That in turn would equal a dose of 153mg/kg (this calculation takes the weight gain into account) for the rats and 25mg/kg for a human being (cf. my article on human equivalent doses). So, if you weighed 80kg you would have to get 2g of catechins, which is the equivalent of 7.5 mini-cups of 100ml tea each brewed from 1g of tea (the last step in this calculation is based on USDA data from 2007).
|Figure 2: Body weight of rats fed either the 40% fructose diet or the same diet enriched with 4% of tea leaves from green, black, oolong or pu-erh tea (data adapted from Huang. 2011)|
Gaining the least weight does not necessarily mean having the "best" blood lipids
Interestingly, a different picture emerges, when we focus exclusively on the blood lipids, where the green tea leaves produce a lipid profile of which current medical "wisdom" tells us that it is the "most beneficial" one ;-)
|Figure 3: Relative changes in serum lipid levels due to fructose feeding and fructose + tea leave feeding (data calculated based on Huang. 2011)|
|Figure 4: Relative changes in AMPK phosphorylation and fatty acid synthethase in rats in response to feeding with 4% of black, green, oolon or pu-erh tea; my quantification on the left, original blots on the right (data calculated based on Huang. 2011)|
Green, Black, Olong, Pu-Erh? Which tea to chose?
If we take a final look at the "whole picture", it appears that the exotic pu-erh tea would be the tea of choice, when you totally discard taste, price and whatever other factors may influence your choice. After all, it is was exactly as effective in ameliorating the weight gain as the black tea, induced an impressive +244% increase in AMPK phosphorylation and had what I, contrary to the medical establishment, would consider the "optimal" effect on the lipid profile of the rodents (a profound decreases in triglycerides, even below the level of rats fed the normal chow, and a +11% increase in HDL over the control diet despite high fructose feeding). The "classics", black and green tea, on the other hand, share a close and still notable second place, while the fancy oolong tea appears to be the least effective in this quartet of natural health promoters, the potency of which, and this is something I cannot emphasize enough, can hardly be explained based on their catechin content alone (cf. figure 1) and thusly renders the use of respective abstracts for the same purpose more than questionable.