Green tea’s health claims questioned: FDA

A new finding and revelation comes in the form of health claims that green tea is no longer a boon to the heart. The petition proposed as a model qualified health claim says "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)."

This petition was posted on the FDA site by FDA on July 28, 2005 as a qualified health claim petition for a 60-day comment period.

According to rules of governance a health claim characterizes the relationship between a substance and a disease or health-related condition (21 CFR 101.14(a)(1)). The substance must be associated with a disease or health-related condition for which the general U.S. population, or an identified U.S. population subgroup is at risk (21 CFR 101.14(b)(1)).

The agency then separates individual reports of human studies from other types of data and information. FDA focuses its review on reports of human intervention and observational studies.

In addition to individual reports of human studies, the agency also considers other types of data and information in its review, such as meta-analyses, review articles and animal and in vitro studies.

FDA uses animal and in vitro studies as background information regarding mechanisms of action that might be involved in any relationship between the substance and the disease. FDA evaluates the individual reports of human studies to determine whether any scientific conclusions can be drawn from each study. The absence of critical factors such as a control group or a statistical analysis means that scientific conclusions cannot be drawn from the study (Spilker et al., 1991, Federal Judicial Center, 2000).

Because health claims involve reducing the risk of a disease in people who do not already have the disease that is the subject of the claim, FDA considers evidence from studies in individuals diagnosed with the disease that is the subject of the health claim only if it is scientifically appropriate to extrapolate to individuals who do not have the disease.

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Next, FDA rates the remaining human intervention and observational studies for methodological quality. This quality rating is based on several criteria related to study design (e.g., use of a placebo control versus a non-placebo controlled group), data collection (e.g., type of dietary assessment method), the quality of the statistical analysis, the type of outcome measured (e.g., disease incidence versus validated surrogate endpoint), and study population characteristics other than relevance to the U.S. population (e.g., selection bias and whether important information about the study subjects--e.g., age, smoker vs. non-smoker--was gathered and reported).

Finally, FDA evaluates the results of the remaining studies.

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Although the model claim proposed in the petition refers only to green tea consumed as an article for drink, the discussion in the petition makes clear that the proposed claim is based on a body of evidence encompassing studies of green tea in both a beverage and an extract form.

It is not necessary for FDA to make a determination about the safety of green tea or green tea extract in this letter because the agency is denying the proposed claims for lack of credible evidence.

FDA has identified the following disease endpoints to use in identifying CVD risk reduction for purposes of a health claim evaluation: the incidence of coronary events (MI, ischemia), cardiovascular death, coronary artery disease, atherosclerosis, and coronary heart disease (CHD). High blood pressure, blood (serum or plasma) total cholesterol, and blood LDL-cholesterol levels are considered surrogate endpoints for all CVDs.[14] These disease and surrogate endpoints were used to evaluate the potential effects of green tea or green tea extract consumption on CVD risk.

Based on FDA's consideration of the scientific evidence and other information submitted with FDA concludes that there is no credible evidence to support qualified health claims for green tea or green tea extract and a reduction of a number of risk factors associated with CVD.