Best Of Theaflavins and Heart HealthFebruary 22, 2011 Written by JP [Font too small?]
As a big fan of movies, quotations from films are often in the forefront of my mind. One line of dialogue that’s made an indelible impression on me is from the 2005 box-office bomb, The Weather Man. In the film, the esteemed actor Michael Caine offers some prescient words of wisdom to his adult son, played by Nicolas Cage. “Do you know that the harder thing to do and the right thing to do are usually the same thing? Nothing that has meaning is easy. ‘Easy’ doesn’t enter into grown-up life”. That advice was given with regard to a failing marriage, but it I think it applies to almost every aspect of life and, quite specifically, to natural medicine.
One of my goals is to try to change a prevalent perception that I see in virtually all sectors of the alternative and conventional medical system. It’s a counterproductive point of view that natural medicine: a) cannot be adequately or fairly studied by using the scientific method; b) natural remedies are more basic or primitive than allophatic medications and treatments and; c) we should expect “black and white” answers to issues regarding the efficacy of holistic therapies. To be clear, this problem is not isolated to the mainstream medical establishment. It extends into the territory of natural health manufacturers, practitioners and even patients.
Here’s the problem in a nutshell: The conventional medical community tends to ignore most natural remedies. But on occasion they do conduct a study or two to scientifically assess the value of a specific practice or supplement. If the results are positive, they’re typically viewed as being “preliminary”. However, if the results are negative or not statistically significant, the remedy in question is considered useless. The problem is that both of these attitudes are over simplifications of the truth. As the old saying goes, “The devil is in the details”. There is no place where that is more true than in the field of medical research.
In order to illustrate how complex it is to properly research an alternative “medicine”, I’d like to present the case of “Theaflavins vs. Cholesterol and Heart Disease”. The reason I’ve chosen this topic is because theaflavins, a class of phytochemicals found primarily in black tea, are currently being marketed as a cardioprotective supplement.
A recent study published in the European Journal of Nutrition casts some doubt on the ability of theaflavins to positively augment lipid levels. This surprising finding is based on a new trial conducted on a group of 102 patients with high cholesterol. The men and women in the study were divided into three sections: 1) received a supplement containing 77.5 mg of “purified black tea theaflavins” daily; 2) a mixture of 75 mg theaflavins + 150 mg of tea catechins and 195 mg of tea polyphenols; and 3) a placebo containing a small amount of plant fiber (cellulose).
- LDL (“bad”) cholesterol, total cholesterol and triglycerides were tested at the start of the study and after weeks 4, 8 and 11.
- There was no significant differences found in the groups receiving any of the three treatments.
The authors of the trial summarized these results in an uncommonly fair minded manner: “Based on these findings it cannot be concluded that tea flavonoids such as theaflavins and catechins are responsible for the putative cholesterol-lowering effect of black tea, at least not with the daily dose applied in the present study”. (1)
This particular trial hasn’t really made much of a splash in the alternative or mainstream media and it’s unlikely to do so anytime soon. But I think it’s important to address it because I believe almost everyone genuinely wants to know which alt-med remedies work and which are a waste of money. That’s why a little detective work is needed here. Theaflavins have been viewed as promising nutraceuticals for managing heart health based on a handful of positive clinical studies that have been trickling in over past several years.
- The December 2009 edition of the British Journal of Nutrition reports that a black tea extract, rich in theaflavins and thearubigins, effectively lowered blood sugar levels, lipids and improved liver function in a group of lab rats. A modulatory effect on body weight was also noted. (2)
- Two recent test tube studies provide a plausible rationale for how theaflavins might encourage reductions in cholesterol concentrations. A laboratory experiment from the University of Kentucky discovered that black tea can inhibit “HMG-CoA reductase”, which is the primary mechanism employed by most cholesterol lowering medications. Researchers in the Netherlands offer up another pathway by which theaflavins can alter lipid levels – by decreasing cholesterol absorption through the intestinal wall. This too is a method by which some medications lower lipids. However, it’s important to note that black tea extract has not demonstrated the same safety concerns as its prescription counterparts. (3,4,5)
- An older study, published in October 2003, determined that drinking 5 cups of black tea/day reduced LDL (“bad”) cholesterol by 11.1%, apolipoprotein B by 5% and lipoprotein(a) by 16.4%. These changes are typically considered favorable with regard to cardiovascular risk. (6)
The cholesterol-lowering track record of black tea first came into question after the publication of the August 2009 issue of the Journal of Alternative and Complementary Medicine. An Iranian study examined the respective effects of two different types of tea on the lipid profiles of 60 diabetic patients over a one month period. The daily consumption of 2 cups of black tea didn’t yield significant changes in LDL, total cholesterol or triglyceride levels. There was, however, a statistically relevant boost in HDL (“good”) cholesterol. (7)
Unlike black tea, green tea supplements are rarely marketed for their ability to influence lipid levels. But a cursory review of the medical literature appears to provide stronger evidence in favor of green tea.
The most recent human trial on green tea involved 33 patients of varying ages (21-71) who were asked to eat a low-fat diet and take either a 250 mg capsule of green tea extract or a placebo for 8 weeks. Half of the participants were given green tea and the remainder the placebo. Blood tests were taken at the start of the trial and at the 8 week mark. After the initial 8 week period, the researchers switched the respective medications given to volunteers. This “crossover” design helps to identify specific changes brought about by the test substance (green tea) vs. the placebo. Minor reductions in LDL (4.5%) and total cholesterol (3.9%) were demonstrated only after the green tea treatment. (8)
A February 2009 trial discovered that a twice-daily dosage of green tea extract, prompted several positive cardiovascular shifts in a group of 111 “healthy adult volunteers”: a drop in both diastolic and systolic blood pressure, LDL cholesterol, malondialdehyde (a measure of oxidative stress) and amyloid-alpha (an inflammatory marker). In addition, a Spanish study from April 2008 found that 5 weeks of daily green tea consumption led to improved vasodilation (vascular function) and a reduction in oxidized cholesterol, which can contribute to plaque accumulation in the arteries and increase risk of heart attacks and stroke. (9,10)
The comparison of black tea and green tea may be more complex than it seems. A group of researchers from Vanderbilt University Medical Center discovered that combining green tea and (black tea) theaflavins may be just the ticket. A 12 week “double-blind, randomized, placebo-controlled” examination of 240 men and women tested the effects of a once-daily capsule of “theaflavin-enriched green tea extract” (375 mg) vs. a placebo. The results of the trial were quite impressive: an 11.3% decline in total cholesterol, -16.4% LDL choleterol and a 2.3% increase in HDL cholesterol. Unfortunately, the green tea + theaflavin therapy in combination with a low-fat diet did not lower triglycerides. On the upside, there were no significant side effects reported. (11)
Update: February 2011 – Theaflavins represent a familiar and unfortunate model in the world of natural health research. Precious few trials have taken place over the past year with respect to black tea and/or theaflavins and heart health. This, despite the frequently compelling data that I cited in the original column. The papers that have been published of late reveal the following: A recent meta-analysis, which reviewed 13 studies on black tea and 5 on green tea, reports that green tea consumption provides more robust protection against coronary artery disease than black tea. The mechanisms by which black tea extracts and/or theaflavins achieve their cardioprotective effects are becoming clearer: a) theaflavins inhibit plasminogen activator inhibitor (PAI-1), which likely supports healthier circulation; b) black tea polyphenols reduce cholesterol absorption and “significantly lower levels of serum and hepatic cholesterol, triglycerides, serum low-density lipoprotein cholesterol, and increased high-density cholesterol” in animals consuming an unhealthy diet; c) black tea also protects against high blood sugar, insulin resistance and subsequent weight gain that typically occurs in rats fed a high-fat diet. Researchers from Kobe University in Hyogo, Japan note that the latter benefits are a consequence of black tea’s ability to improve “glucose uptake activity”. The question that remains is whether or not these laboratory results ultimately translate into real cardiovascular benefits in human populations. The only way to accurately determine and quantify this is through more controlled research. I hope the next time I revisit this topic, there will be more hard data to consider. (12,13,14,15,16)
Note: Please check out the “Comments & Updates” section of this blog – at the bottom of the page. You can find the latest research about this topic there!
Tags: Cholesterol, Diabetes, Tea
Posted in Alternative Therapies, Food and Drink, Heart Health