Does Green Tea Prevent Cardiovascular Disease?
By William Faloon
By William Faloon
On May 9, 2006, the FDA stated that there was no credible evidence to support the claim that green tea reduces cardiovascular disease risk factors.1
The FDA’s 21-page letter of denial was in response to a petition filed by a maker of green tea bags that sought to state a cardiovascular risk-reduction health claim on the label of its product.
Although the FDA identified dozens of published scientific studies suggesting that green tea might reduce heart attack and stroke risk, the agency decided that none of these studies met its criteria for allowing a health claim on the labels of green tea products.
On September 13, 2006, the Journal of the American Medical Association published a study that tracked the green tea consumption of 40,530 adults over an 11-year period. The study found that those who drank five or more cups of green tea a day cut their overall death rate by 16% compared to those who drank less than one cup of green tea a day.2
The most striking finding from this study was the reduction in cardiovascular death in those who consumed the most green tea. Women who drank five or more cups of green tea daily had a 31% reduced risk of dying from cardiovascular disease, whereas men who drank five or more cups had a 22% reduced risk of dying from cardiovascular disease.2
Stroke was the type of cardiovascular mortality against which green tea was shown to be most effective. Women who drank five or more cups of green teas had a 42% lower risk of stroke compared to those who drank less than one cup a day.2
Why the FDA Disagrees with Study Findings
The FDA’s criteria for allowing a health claim on the label of a food or dietary supplement is quite archaic. For example, the FDA does not recognize low-density lipoprotein (LDL) oxidation as a validated cardiovascular disease risk factor. Therefore, scientific studies in humans showing that green tea extract inhibits LDL oxidation are excluded from the FDA’s analysis of green tea’s efficacy.
The FDA’s antiquated position flies in the face of voluminous data showing that oxidized LDL severely damages the arterial wall and is a major contributor to atherosclerosis-induced heart attack and stroke.3-22
When choosing which studies of green tea to evaluate, the FDA excluded those that did not show significant reductions in total cholesterol, LDL, or blood pressure. According to the FDA’s logic, if green tea does not lower cholesterol, LDL, or blood pressure, then a claim cannot be made on a green tea label that it reduces cardiovascular disease risk factors. The FDA did acknowledge studies in which people who consumed 10 cups of green tea a day showed a significant decrease in total cholesterol and LDL.
Completely overlooked by the FDA analysis are published studies showing that green tea protects against heart attack and stroke via mechanisms (such as inhibiting abnormal platelet aggregation)23-32 that are different than the rudimentary measurements to which the FDA limited its green tea evaluation.
The FDA also made it clear that all in vivo animal studies are excluded from its analysis because these studies cannot mimic normal human physiological response to green tea ingestion. The FDA then found a reason to invalidate every human study that had ever shown a cardiovascular benefit in those who consumed green tea.
The FDA’s conclusion was that no credible evidence existed to support a cardiovascular risk-reduction claim on the label of green tea products.1 The recent study published by the American Medical Association, which included more study subjects and lasted far longer than any other previous study, did show a cardiovascular benefit to drinking greater amounts of green tea. Who then should consumers believe?2
Misconceptions About Green Tea Beverages
When green tea is consumed as a beverage, relatively little of its active polyphenols are absorbed into the bloodstream. This helps explain some inconsistent findings about how effective green tea may be in preventing common diseases.
The study published by the American Medical Association showed that daily ingestion of five or more cups of green tea reduced cardiovascular mortality and overall death rates. It also showed that those who drank two to four cups of green tea a day had less disease than those who drank less than one cup a day. This particular study failed to show a cancer risk reduction.2
The findings from another large human study, however, did show a 41% reduction in cancer incidence in those who consumed over 10 cups of green tea a day compared to those who consumed less than 3 cups a day. This same study showed a 28% reduction in cardiovascular disease incidence in those consuming 10 cups of green tea compared to those drinking less than 3 cups.33
Even the FDA’s unfavorable report on green tea pointed to studies showing that daily intake of 10 cups of green tea lowered total cholesterol and LDL.34
It would appear from these studies that optimal benefits from green tea occur when one drinks 10 or more cups a day. The problem is that few people are ever going to ingest 10 or more cups of green tea every single day. The good news is that they don’t have to.
Green Tea Extracts vs. Green Tea Beverages
Mainstream doctors often advocate obtaining nutrients from foods rather than supplements. A problem with certain nutrients, however, is that they are bound so tightly to food that less-than-optimal amounts of the active constituents are absorbed into the bloodstream.
Examples of nutrients that are better absorbed from supplements than from food include vitamin K, folic acid, and chlorophyll.35-37 Lycopene, on the other hand, may be better absorbed from cooked tomato products38 than from supplements.
In a recent study published in the American Journal of Clinical Nutrition, scientists sought to determine whether the active ingredients in green tea were better absorbed from green tea extract capsules or by drinking green tea. Thirty healthy test subjects were recruited and given either a specially prepared green tea beverage standardized for green tea’s most active constituents (such as EGCG and ECG) or equally standardized green tea extract capsules.39
The results showed that subjects who received the green tea extract caps had a 60% greater increase in EGCG (epigallocatechin gallate) and a 90% greater increase in ECG (epicatechin gallate) compared to those who drank the identical amounts of these green tea constituents in standardized beverage form. The antioxidant effects in those who swallowed the green tea caps were also greater than in the green tea drinkers.39
The scientists concluded that when administered in the form of a green tea supplement, the active constituents (polyphenols) showed enhanced bioavailability compared to when identical amounts of polyphenols were provided in a green tea beverage.39
One reason for conducting this study were previous findings that green tea polyphenols might be effective in preventing and treating cancer. By documenting that green tea extract supplements are superior to drinking green tea beverages, scientists now have a solid basis to test green tea extract capsules in human clinical studies.
Not All Green Tea Beverages Are the Same
The amount of polyphenols contained in green tea beverages varies considerably, depending on where the tea is harvested and how it is processed. One study examined 19 commercial brands of green tea and found significant variation in the content of the polyphenols EGCG and ECG. The scientists who conducted this study recommended that the labels of green tea bags state the amount of the polyphenols (EGCG and ECG) contained in each cup so that consumers know how many milligrams of these active ingredients they are consuming each day.40
Did the FDA Actually Get It Right This Time?
The FDA’s denial of a cardiovascular health claim was in response to a petition filed by a maker of green tea bags that sought to state that daily consumption of about one cup of green tea would reduce cardiovascular risk factors. The amount of polyphenols in this particular brand of green tea was 125 mg per cup.
Based on our analysis of the published scientific literature, it takes more than 125 mg a day of polyphenols to reduce cardiovascular risks. Although the FDA never mentioned this in its 21-page letter of denial, it would appear the FDA made the right scientific decision in disallowing this particular health claim on the label of green tea bags.
The good news for consumers is that green tea extract prices continue to plummet. This enables virtually everyone to ingest just two green tea extract capsules a day and obtain the amount of polyphenols (about 1250 mg) contained in 10 cups of green tea.
For longer life,
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