Extracts from black tea may reduce total cholesterol levels by 9 per cent and LDL cholesterol levels by 12 per cent, according to a new study from Japan.

Consumption of the black tea extract (BTE) was also associated with beneficial changes in blood levels of triglycerides and body weight, according to results published in the journal Nutrition Reviews.

High cholesterol levels, hypercholesterolaemia, have a long association with many diseases, particularly cardiovascular disease (CVD), which is the number one killer on both sides of the Atlantic.

“The present study is the first to report that BTE (one gram per day) significantly lowered total cholesterol and LDL cholesterol levels in human subjects with borderline hypercholesterolemia in a randomised double-blind placebo-controlled study,” wrote authors Hiroyuki Fujita and Tomohide Yamagami from the R&D Department of Nippon Supplement in Osaka.

The study involved 47 people with borderline hypercholesterolaemia assigned to receive the BTE or placebo for three months.

The health benefits of tea have been linked to the polyphenol content of the tea. Green tea contains between 30 and 40 per cent of water-extractable polyphenols, while black tea (green tea that has been oxidised by fermentation) contains between 3 and 10 per cent.

The four primary polyphenols found in fresh tea leaves are epigallocatechin gallate (EGCG), epigallocatechin, epicatechin gallate, and epicatechin.

Study details

The subjects, aged from 40 to 70 years, were randomly assigned to receive the black tea extract (one gram per day) or placebo for three months. The subjects consumed the extract before a meal.

After three months, a 9 per cent reduction in total cholesterol was observed in the tea extract group, from 6.14 to 5.62 moles per litre at the start and end of the study, respectively. Furthermore, LDL cholesterol levels fell by 12 per cent, from 4.32 to 3.81 moles per litre.

Similar reductions in triglyceride levels were observed, but no significant changes in any blood lipid levels were recorded in the placebo group.

“Interestingly, the reduced levels of total cholesterol, LDL cholesterol, and TG levels remained significant even one month after termination of black tea extract intake,” wrote Fujita and Yamagami.

The authors also note no “undesirable changes in other biochemical parameters”, such as fat-soluble vitamins. Moreover, none of the subjects reported any adverse effects from consumption of the black tea extracts.

Mechanism

Fujita and Yamagami postulated that the tea extract may function by inhibiting the reabsorption of bile acids. By binding to the bile acids the extracts increase the excretion of cholesterol - the liver compensates by producing more bile from cholesterol, thereby promoting cholesterol lowering.

“Because the black tea extract induces the precipitation of mixed bile salt micelles and lowers blood cholesterol levels, it might have contributed to body weight loss in this study,” they wrote.

“In this regard, further investigation of black tea extract effects on body weight loss is warranted,” they concluded.

They also stated that future studies should investigate if the extract can play a role in reducing arteriosclerosis related to the metabolic syndrome and obesity in humans.

By Stephen Daniells

The benefits of green tea might include blocking fat and keeping extra pounds at bay, according to preliminary lab tests in mice.

Don’t skip over that word “preliminary.” There’s no proof yet that sipping green tea will do the same for people. Staying in shape continues to be a balancing act between calories and activity.

Here’s what those preliminary lab tests in mice show:  

• Less weight and fat gain. Among mice with an obesity gene, those that ate chow laced with green tea extract gained less weight and less fat.
• Less fat in the liver. There was less sign of “fatty liver” disease in the mice with the obesity gene that ate chow laced with green tea extract.
• Lower cholesterol and triglyceride levels in mice with the obesity gene that ate the chow laced with green tea extract, compared to other mice with the same obesity gene.

A healthy liver isn’t fatty. But obesity - in mice or in people - can lead to fatty buildup in the liver and cause nonalcoholic fatty liver disease.

As for that green tea extract, the study used it in doses equal to what a person would get from drinking at least seven cups of green tea a day.      (WebMD)