Home / Resources / Articles / Drinking Green Tea Reduces CVD Mortality

Drinking Green Tea Reduces CVD Mortality

Sep 26, 2006
 

A prospective cohort study of more than 40,000 people in Japan has shown that drinking green tea can significantly cut deaths from cardiovascular disease (CVD) as well as all-cause mortality, particularly in women. Shinichi Kuriyama, MD, from Tohuku University Graduate School of Medicine in Miyagi, Japan, told Diabetes in Control, "I think our study provides strong evidence regarding the benefits of drinking green tea in humans on CVD, but not cancer, with a large sample size."

"The reason for the discrepancy between effects on CVD and on cancer deaths in our study is uncertain. Substantial evidence from in vitro and animal studies indicates that green tea preparations can inhibit both CVD and carcinogenic processes.

 

owever, recent epidemiological studies have indicated that green tea consumption is associated with reduced cardiovascular risk profiles but have demonstrated almost null data regarding the association between green tea consumption and cancer at various sites. Our results are almost consistent with those of the recent epidemiologic studies."

Dr. Kuriyama and colleagues explain that almost all Japanese people consume green tea as one of their favorite beverages. They designed their prospective analysis to examine the association between green tea consumption and mortality due to all causes, CVD, and cancer within a large population-based cohort study of 40,530 people in Miyagi Prefecture in northeastern Japan.
For 11 years (follow-up rate for all-cause mortality, 86.1%), 4209 participants died, and for up to 7 years, (follow-up rate for cause-specific mortality, 89.6%), 829 people died of CVD, and 1134 died of cancer.

Compared with participants who drank less than 1 cup of green tea per day, those who consumed 5 or more cups had a risk for all-cause and CVD mortality that was 16% lower (during 11 years of follow-up) and 26% lower (during 7 years of follow-up), respectively.

The inverse association with CVD mortality was stronger than that with all-cause mortality, and among the types of CVD, the strongest inverse association was seen for stroke mortality.

The inverse association between green tea consumption, CVD, and all-cause mortality was stronger in women than in men (P = .08 for interaction with sex). In women, the multivariate hazard ratios of CVD mortality across increasing green tea consumption categories (cups/day) were 1.00, 0.84, 0.69, and 0.69, respectively (P = .004 for trend).

"The reason for the discrepancy between men and women for the association of green tea consumption and risk of all-cause and CVD mortality is uncertain," say the researchers.

The authors add that the effect of green tea "appears to be a threshold effect rather than a dose-response relationship, such that persons who consume at least 1 cup a day may receive some benefit."

A number of biological mechanisms, including radical scavenging and antioxidant properties, have been proposed for the beneficial effects of green tea. The authors note that previous studies have suggested that green tea favorably affects hypertension, low-density lipoprotein cholesterol levels, and atherosclerosis.

JAMA. 2006;296:1255-1265.

================================

Start your own walking program
New StepTracker Available at special prices. See the results of the Step Program Study.
http://www.diabetesincontrol.com/programs/steps/index.shtml
Purchase your own pedometers and receive the Steps to Health Program at no charge. http://www.rx4betterhealth.com/steptracker/
The Only Pedometer on the Market That Comes With a Program for Success!

================================

DID YOU KNOW:
There is a 21 percent increase in heart attacks, for every 1 percentage point increase in hemoglobin A1c above 5 percent. Dr. Kay-Tee Khaw of Cambridge University and colleagues at Britain’s Medical Research Council studied 10,030 people aged 45 to 79 for six years. They found a 21 percent increase in cardiovascular "events" such as heart attack, for every 1 percentage point increase in hemoglobin A1c above 5 percent. "Persons with HA1c concentrations less than 5 percent had the lowest rates of cardiovascular disease and mortality," they wrote. This was true even when patients were older and fatter and regardless of blood pressure or cholesterol levels. Glycosylated hemoglobin level is an independent progressive risk factor for incident cardiovascular events, regardless of diabetes status" Dr. Hertzel Gerstein of McMaster University in Ontario, Canada wrote in a commentary. "Glycosylated hemoglobin level can now be added to the list of other clearly established indicators of cardiovascular risk, such as blood pressure and cholesterol level," added Gerstein, a diabetes expert.