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Pregnant women have been advised to keep their consumption of coffee and other caffeinated beverages (tea, sodas, cocoa, energy drinks), and chocolate containing foods to a minimum for decades. Currently the American College of Obstetrics recommends that women consume less than 200 mg of caffeine (from any source) per day during pregnancy. This is less than 2 cups of regular coffee  or 4 cups of regular black tea. But a recent  study's findings suggest that the levels should be kept much lower.

The study of 941 mother/baby pairs in Ireland found that each 100 mg increase of caffeine per day was associated with a lower birth weight, shorter length of pregnancy (gestational age), shorter birth length of the baby, and smaller head circumference of the baby at birth. The strongest associations between those who consumed the most caffeine (when compared to those who consumed the least) was with lower birth weight. The researchers think this occurs because caffeine crosses the placenta easily, but during pregnancy there is a slowed metabolism of caffeine (so it takes longer to get it out of the body). Similar results have been found in other recent studies. [On the other hand, for not pregnant women - coffee and tea are linked to all sorts of health benefits - here, here.]

From Medical Xpress: Caffeinated beverages during pregnancy linked to lower birth weight babies

...continue reading "Keep Caffeine To A Minimum During Pregnancy"

OK, this study was done in mice, but it's the kind of study results that everyone hopes (and thinks) is also true for humans. So drink a nice cuppa black tea and think about how you're increasing bacteria in the gut associated with weight loss.

Black tea (as well as green tea) has polyphenols that stimulate the growth of gut bacterium and the formation of short-chain fatty acids. By the way, the mice were given decaffeinated tea extracts, so theoretically both decaf and caffeinated tea should have benefits. The big question though is - will drinking black tea daily actually result in weight loss? From Medical Xpress:

Black tea may help with weight loss, too

UCLA researchers have demonstrated for the first time that black tea may promote weight loss and other health benefits by changing bacteria in the gut. In a study of mice, the scientists showed that black tea alters energy metabolism in the liver by changing gut metabolites. The research is published in the European Journal of Nutrition. The study found that both black and green tea changed the ratio of intestinal bacteria in the animals: The percentage of bacteria associated with obesity decreased, while bacteria associated with lean body mass increased.

Previous studies indicated that chemicals in green tea called polyphenols are absorbed and alter the energy metabolism in the liver. The new findings show that black tea polyphenols, which are too large to be absorbed in the small intestine, stimulate the growth of gut bacterium and the formation of short-chain fatty acids, a type of bacterial metabolites that has been shown to alter the energy metabolism in the liver.

The researchers also collected samples from the mice's large intestines (to measure bacteria content) and liver tissues (to measure fat deposits). In the mice that consumed either type of tea extract, there was less of the type of bacteria associated with obesity and more of the bacteria associated with lean body mass. However, only the mice that consumed black tea extract had an increase in a type of bacteria called Pseudobutyrivibrio, which could help explain the difference between how black tea and green tea change energy metabolism.

The new study also concluded that both green tea and black tea have different effects on liver metabolism. According to Henning, the molecules in green tea are smaller and can more readily be absorbed into the body and reach the liver directly, while black tea molecules are larger and stay in the intestine rather than being absorbed. When black tea molecules stay in the intestinal tract, they enhance the growth of beneficial bacteria and the formation of microbial metabolites involved in the regulation of energy metabolism. [Original study.]