The Durk Pearson & Sandy Shaw®
Life Extension NewsTM
Volume 12 No.
4 • August 2009
High Triglycerides, Diabetes: Black Tea Suppresses Postprandial Hypertriacylglycerolemia
Hypertriacylglycerolemia (high levels of triglycerides), especially following a meal (postprandial) is a prominent risk factor for cardiovascular disease in diabetics (possibly even more important than high blood sugar levels) and in non-diabetics, too.
A new paper reports that black tea polyphenols (BTP, derived from an ethanol extract of dried black tea leaves) administered to 8 week old male Wistar rats reduced the blood level of triacylglycerols (triglycerides) following an infusion into the stomach of a fat emulsion (immediately after the BTP) as compared to another group of rats that received the fat emulsion but not the black tea polyphenols (BTP). In fact, the high-BTP group of rats had triacylglycerol levels following the fat emulsion that remained almost at basal levels (e.g., there was practically no increase).
Further investigation found that the BTP dose-dependently inhibited pancreatic lipase in vitro, which is probably the mechanism responsible for BTP reduction of blood triacylglycerols in the rats, though no test for an effect of pancreatic lipase in the rats was done. Though the researchers note that they used relatively high amounts of black-tea components in order to obtain a “conspicuous” difference, they “consider that the effective dose of BTP in humans can be lower than that used in rats.” As they explained, they had done an earlier study that showed that green tea catechins suppressed postprandial hypertriacylglycerolemia in rats. In that study, they gave the rats 100 mg/kg of body weight of green tea catechins. But in a human study, they found that the green tea catechins suppressed postprandial hypertriacylglycerolemia at 215 mg per person, much less than that given the rats (Unno et al. Suppressive effects of tea catechins on elevation of postprandial serum triglycerides. Jpn J Nutr Assessment [in Japanese] 22:207-12 (2005).)
The components of black tea that were effective in inhibiting pancreatic lipase activity were theaflavins with galloyl moieties (theaflavin-3,3’-digallate was more effective than epigallocatechin gallate [EGCG], epicatechin gallate, and a mixture of EGCG and epicatechin gallate).
- Unger RH. Reinventing Type 2 diabetes. JAMA 299(10):1185-7 (2008). “[T]he novel lipocentric view depicts the hyperglycemia of type 2 diabetes, and the underlying insulin resistance and beta cell loss, as being secondary to the metabolic trauma caused by ectopic lipid deposition [abnormal fat accumulation taking place outside of adipose tissue] or lipotoxicity. If this is the case, hyperglycemia should be corrected by eliminating the lipid overload.” A recent study [Dixon et al. Adjustable gastric banding and conventional therapy for type 2 diabetes: a randomized controlled trial. JAMA 299:316-23 (2008).] “[P]rovides support for this lipocentric hypothesis, by demonstrating that weight loss that follows gastric banding is accompanied by remission of diabetes in 73% of obese patients with type 2 diabetes.”
- Kobayashi et al. “Black tea polyphenols suppress postprandial hypertriacylglycerolemia by suppressing lymphatic transport of dietary fats in rats,” J Agric Food Chem 57:7131-6 (2009).