Coffee and green tea could lower the death risk for Type 2 diabetes sufferers — but only if they drink a certain amount, according to a new observational study published in the online journal BMJ Open Diabetes Research & Care.
For the study, which was peer-reviewed, researchers tracked the health of some 4,923 people in Japan with type 2 diabetes for about 5 years. Participants — 2,790 were men, and 2,133 were women — filled out a questionnaire that involved 58 questions about their food and drink habits, including how much green tea and coffee they drank each day. Participants were also asked to provide information on how often they exercised and if they smoked or consumed alcohol, and how much sleep they averaged each night, among other lifestyle inquiries.
Of the 4,923 people surveyed, 607 said they didn’t drink green tea at all, and 1,143 said they drank a cup a day. Some 1,384 said they drank two to three cups a day, and 1,784 reported drinking four or more cups daily. As for coffee consumers, 994 said they didn’t drink the beverage, and 1,306 said they drank “up to one cup daily.” Another 963 said they drank a cup every day, while 1,660 said they consumed two more cups.
Over the five years the participants were tracked, 309 died, with the main causes of death being cancer and cardiovascular disease.
Interestingly, the researchers noted that compared to those who drank neither green tea nor coffee, those who drank one or both beverages “had lower odds of dying from any cause, with the lowest odds associated with drinking higher quantities of both green tea and coffee,” per a news release regarding the findings.
More specifically, for green tea, drinking up to one cup a day was linked to a 15% lower risk of death, while those who drank between two and three cups had a 27% lower risk. Drinking four or more cups of green tea was associated with a whopping 40% lower risk of death.
Coffee drinkers saw similar benefits. Those who consumed up to one cup each day had a 12% lower risk, while those who drank one cup a day had 19% lower odds. Meanwhile, two or more cups were associated with 41% lower odds, the researchers found.
“The risk of death was even lower for those who drank both green tea and coffee every day: 51% lower for two to three cups of green tea plus two or more of coffee; 58% lower for four or more cups of green tea plus one cup of coffee every day; and 63% lower for a combination of four or more cups of green tea and two or more cups of coffee every day,” per the release.
“People with Type 2 diabetes are more prone to circulatory diseases, dementia, cancer, and bone fractures. And despite an increasing number of effective drugs, lifestyle modifications, such as exercise and diet, remain a cornerstone of treatment,” the researchers wrote, noting that past research suggests that regularly drinking coffee and green tea “may be beneficial for health because of the various bioactive compounds these beverages contain.” However, few studies have looked at the effects of these beverages in those with diabetes.
“This prospective cohort study demonstrated that greater consumption of green tea and coffee was significantly associated with reduced all-cause mortality: the effects may be additive,” the researchers concluded, per the news release.
The study did have limitations, however. Being an observational study, a cause was not established, and caveats included “the reliance on subjective assessments of the quantities of green tea and coffee drunk.”
The study comes after past research has determined that coffee may protect the liver, while another study found the beverage could aid in colon cancer patients’ longevity. As for green tea, a study published in the European Journal of Preventive Cardiology in January found that drinking green tea instead of black tea could extend one’s life.