12 January - 20 June 2016

Black tea polyphenols may also be good for weight loss

Polyphenols in green tea (GT) and black tea (BT) have previously been found to have numerous health benefits including inhibiting weight gain in mice fed a high fat, high sucrose diet. However, whilst green tea polyphenols are absorbed in the small intestine, black tea polyphenols such as theaflavins and thearubigins, due to their large molecular weight, are not; they are transported to the colon.

Polyphenols in green tea (GT) and black tea (BT) have previously been found to have numerous health benefits including inhibiting weight gain in mice fed a high fat, high sucrose diet.  However, whilst green tea polyphenols are absorbed in the small intestine, black tea polyphenols such as theaflavins and thearubigins, due to their large molecular weight, are not; they are transported to the colon. Green tea polyphenols such as epigallocatechin gallate and epicatechin have been found to “decrease in digestion and absorption of lipids in the intestine”.  A study published in the European Journal of Nutrition has speculated “that changes in the microbiota may represent an important mechanism for black tea polyphenols (BTP) and possibly green tea polyphenols (GTP) to induce weight loss.” Therefore, the objective of this mouse study was to determine whether the intestinal microflora plays a role in the anti-obesogenic effects of GT and BT.

The scientists split 48 male mice into four groups and fed them either a low fat, high sugar diet; a high fat, high-sugar diet, a high fat, high sugar diet supplement with GT extracts or a high fat, high sugar diet supplemented with black tea extracts for 4 weeks. The supplementation with GTP and BTP was at 0.5g/100g of diet providing 0.25 g polyphenols/100g diet.  Henning et al report that "based on the food intake, we calculated that mice fed the GTP diet in average consumed 240 mg of GTP and 320 mg of BTP per kg body weight." Henning et al recorded body weights weekly and food consumption three times per weeks.  After intervention, the mice were sacrificed and Henning et al. measured bacteria content in the large intestine and analysed fat deposits in liver tissues.

Compared to the mice who were fed the low fat, high sugar diet, the mice fed the high fat, high sugar mice had a significantly higher body weight and "subcutaneous and epididymal fat by weight."  However, supplementation with GT and BT polyphenols resulted in the mice having similar body composition to the mice fed the low fat, high sugar diet.  The supplemented mice were found to have less of the type of bacteria associated with obesity and more of the bacteria associated with lean body mass (a decrease of Firmicutes and increase in Bacteroidetes).  Henning et al. report that only the mice that consumed the black tea extract had an increase in the bacteria Pseudobutyrivibrio and increased formation of short chain fatty acids.  The increase in short chain fatty acid formation has been associated with alteration of the energy metabolism in the liver.

The authors concluded by stating "It was known that green tea polyphenols are more effective and offer more health benefits than black tea polyphenols since green tea chemicals are absorbed into the blood and tissue.  Our new findings suggest that black tea, through a specific mechanism through the gut microbiome, may also contribute to good health and weight loss in humans."

RSSL can analyse green tea for catechins, including epigallocatechin-gallate (EGCG) and epigallocatechin (EGC). To find out more please contact Customer Services telephone 0118 918 4076 or e-mail enquiries@rssl.com

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