According to biotechnologists at National Chung Hsing University in Taiwan, Ching-Shin Oolong tea contains phenols that boost the secretion of growth hormone. In-vitro and animal studies have shown that these compounds activate the receptor for the hunger hormone ghrelin.
Chin-Shin Oolong Tea
Chin-Shin Oolong Tea is used in Taiwan to increase the appetite of people who are weak. Because ghrelin is released when the stomach is empty and it does the body good to consume sources of energy, the researchers wondered whether Chin-Shin Oolong Tea contains substances that imitate the effect of ghrelin.
To start with the Taiwanese compared the composition of Chin-Shin Oolong Tea with that of an Oolong tea that doesn’t induce feelings of hunger. They found two substances in Chin-Shin Oolong Tea that were not present in the other Oolong teas.
The researchers called these substances teaghrelins. The structural formula of teaghrelin-1 is shown here. If you exchange the methoxy group right at the top for a hydroxyl group you get teaghrelin-2.
The researchers then did a series of experiments with teaghrelin-1.
The researchers gave rats, that hadn’t eaten for two hours, an oral dose of 0 [Control], 2.5 or 7.5 mg teaghrelin-1 per kg bodyweight. The figure below shows that the rats started to eat more, the more teaghrelin-1 they’d been given.
Finally the Taiwanese exposed cells from the rats’ pituitary gland to teaghrelin-1 in test tubes. The concentration was 10-5 M. The figure above shows that the cells started to secrete more growth hormone as a result. The effect of teaghrelin-1 was of the same order as the effect of the peptide GHRP-6 (concentration: 10-7 M) GHRP-6 is a peptide that interacts with the ghrelin receptor.
There are still no approved drugs on the market that stimulate appetite via the ghrelin receptor or that boost the secretion of growth hormone. Trials so far have shown the effect to be limited and that the substances tested have side effects.
“According to this study, teaghrelins extracted from oolong teas seem to be promising oral agonists of the ghrelin receptor, provided that they undergo necessary clinical trials”, the researchers wrote in conclusion.