The U.S. Food and Drug Administration, which last year disallowed a green tea health claim for most kinds of cancer, has now turned down a health claim for green tea and cardiovascular disease.
In a May 9 letter, FDA Director of the Office of Nutritional Products Labeling and Dietary Supplements Barbara Schneeman denied an application by NY-based Ito En tea company for a qualified health claim that would have stated: " Daily consumption of at least 5 fluid ounces (150 mL) of green tea as a source of catechins may reduce a number of risk factors associated with cardiovascular disease. FDA has determined that the evidence is supportive, but not conclusive, for this claim. (Green tea provides 125 mg catechins per serving when brewed from tea and 125 mg catechins as a pre-prepared beverage)."
Schneeman wrote that the FDA evaluated 18 studies linking green tea and cardiovascular disease. Nine studies were disallowed because they didn't measure total blood cholesterol, LDL cholesterol or blood pressure.
Two studies were copies of existing studies the FDA had. Another two studies didn't include a control group. One study didn't conduct statistical analysis between the control group and intervention group. "Statistical analysis of the relationship is a critical factor because it provides the comparison between subjects consuming green tea and those not consuming green tea to determine whether there is a reduction in [cardiovascular disease] risk," Schneeman wrote.
Four studies didn't find any significant difference in systolic or diastolic blood pressure between the groups that consumed green tea and the control groups.
The FDA also evaluated 11 studies of green tea extracts. Two didn't measure total cholesterol, LDL cholesterol or blood pressure, and four studies didn't have control groups. Another two didn't conduct statistical analysis between the control and intervention groups.
The remaining three studies didn't find a difference between blood cholesterol levels in the green tea extract groups and the control groups.
Based on these findings, Schneeman concluded that there was no credible scientific evidence supporting a link between green tea and cardiovascular disease reduction.
The only health claim the FDA currently allows for green tea is a lukewarm one:
- Two studies do not show that drinking green tea reduces the risk of breast cancer in women, but one weaker, more limited study suggests that drinking green tea may reduce this risk. Based on these studies, FDA concludes that it is highly unlikely that green tea reduces the risk of breast cancer.
- One weak and limited study does not show that drinking green tea reduces the risk of prostate cancer, but another weak and limited study suggests that drinking green tea may reduce this risk. Based on these studies, FDA concludes that it is highly unlikely that green tea reduces the risk of prostate cancer.
"The use of green tea as a medicinal beverage has a history of more than 5,000 years. In comparison, the FDA, although given tremendous discretionary powers to decide what foods we eat and what medicines we take, is only in existence for a few decades. Some misunderstanding is unavoidable," said Dr. Sin Hang Lee, who applied to the FDA in 2004 for a green tea and cancer health claim. However, he pointed out, "The fact that the FDA even agreed to consider and to make a decision on green tea health claim petitions is good news for green tea consumers."