The restorative powers of a cup of tea are often spoken of, but we'd always assumed it was mainly cultural rather than necessarily science based. However, a new study confirms that drinking tea can in fact have some real, provable health benefits: improving gut health, as well as helping to regulate your circadian rhythms (the body clock that controls your sleep-wake cycle).
An out-of-whack circadian rhythm, the kind that can result from irregular shift work or jet lag, can alter your metabolism, disrupt your blood sugar levels and lead to a higher risk of type 2 diabetes and obesity.
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These negative effects are, at least in part, due to the status of the bacteria in your gut, says Dr Carrie Ruxton, from the Tea Advisory Panel (who knew such a thing existed?). "Trillions of bacteria live in our gut – called the microbiota – and these can influence not only obesity levels and blood sugar control, but signals in the brain that make us feel sleepy or awake," explains Carrie.
A study published in Critical Reviews in Food Science and Nutrition found that simulated jet-lag caused changes in study subjects' gut microbiota, leading to weight gain and disrupted blood glucose levels. When a sample of gut microbiota from those jet-lagged study subjects was transplanted into non-jet-lagged study subjects, the new group's metabolism was similarly affected.
So here's the good part: "Studies show that plant compounds found naturally in tea – called polyphenols – have a striking effect on the gut microbiota, and encourage growth and activity of ‘friendly’ lactobacillus species,” says Carrie. These polyphenols can be found in a range of teas, including black tea, green tea, oolong and pu-erh.
That means that if you're struggling with the impact of sleep deprivation, drinking team can influence your body clock, and also help you avoid the longer-term negative impacts.