Drinking green tea or coffee lowers the risk of death by up to 62% for stroke and heart attack survivors, study finds
- Researchers used a cohort of 46,000 people aged 40 to 79 for their research
- Each of these people in Japan had filled in surveys on lifestyle, health and diet
- Those who consume green tea regularly had a lower risk of dying from stroke
- Drinking coffee regularly reduced the risk of having a stroke in healthy people
A cup of green tea or coffee every day can lower the risk of death for heart attack or stroke survivors and lower the risk of a heart attack in healthy people, study finds.
Researchers from Osaka University in Suita analysed data from more than 46,000 participants aged 40 to 79 who were part of the Japan Collaborative Cohort Study.
As part of the study volunteers were asked to fill in questionnaires on lifestyle, medical history and diet – including tea and coffee consumption.
When compared with people who rarely drink green tea, those stroke survivors who consume at least seven cups per day had a 62 per cent lower chance of dying.
The study also found people who drink a single cup of coffee per day were 22 per cent less likely to die if they’d had a stroke compared to non-coffee drinkers.
Lead author Hiroyasu Iso said this was an observational study and didn’t investigate why green tea and coffee reduce death risk, so couldn’t explain the cause.
When compared with people who rarely drink green tea, those stroke survivors who consume at least seven cups per day had a 62 per cent lower chance of dying. Stock image
BENEFITS OF GREEN TEA
Green tea has been said to have a number of health benefits including improving brain function.
This is in part due to the antioxidants found within the drink
A recent study claimed it could reduce the risk of death from heart attack or stroke by up to 62 per cent.
Other claims for green tea include:
- Improved brain function
- Help losing weight
- Protection against cancer
- Reduced risk of heart disease
Previous research has examined the benefits of green tea and coffee on heart health in people without a history of cardiovascular disease or cancer, but this study was also able to examine instances in those with pre-existing conditions.
Researchers sought to determine the effects of green tea and coffee consumption after surviving a stroke or heart attack.
‘There is a strong need for scientific evidence on the lifestyles among survivors of stroke and heart attack,’ says Hiroyasu Iso, study corresponding author.
He said it was particularly important ‘considering the rapidly ageing population and the need to improve life expectancy following these cardiovascular events.’
This is where the Japan Collaborative Cohort Study came to help – with more than 46,000 participants, split into those with a history of stroke, a history of heart attacks and those with no history of either condition.
Each participant completed a series of questionnaires from 1988 – 1990, including information on their demographics, lifestyle, medical history and their diet – including how much green tea and coffee they drank.
The researchers analysed their answers, along with information from 2009 on whether any of the participants had died.
When compared with participants who rarely drank green tea, stroke survivors who consumed at least seven cups of green tea daily lowered their risk of all-cause mortality by approximately 62 per cent, they discovered.
Heart attack survivors who drank one cup of coffee a day reduced their overall risk of death by 22 per cent when compared to those who did not regularly drink coffee.
People without a history of stroke or heart attack who consumed one or more cups of coffee a week had approximately a 14 per cent lower risk of all-cause mortality compared to non-coffee drinkers, the researchers discovered.
Lead author Hiroyasu Iso said this was an observational study and didn’t investigate why green tea and coffee reduce death risk, so couldn’t explain the cause. Stock image
Green tea consumption can prevent further cardiovascular events in survivors, while drinking coffee can prevent such events even in the case of healthy individuals.
They did raise a word of caution when comparing green tea in Japan to that consumed as part of a more western diet.
‘An important distinction to make is that in Japanese culture, green tea is generally prepared with water and without sugar,’ said Iso.
Additionally, coffee is prepared with water and occasionally milk and sugar. ‘The healthiest way to prepare these beverages is without an unnecessary amount of added sugars,’ he explained.
Researchers note that this study was observational, and the reason why drinking green tea and coffee lowered the risk of heart attack and stroke cannot be determined.
Further research is needed to understand the details in the different effects of green tea and coffee.
The findings have been published in the journal Stroke.
THE CAUSES OF STROKE
There are two kinds of stroke:
1. ISCHEMIC STROKE
An ischemic stroke – which accounts for 80 percent of strokes – occurs when there is a blockage in a blood vessel that prevents blood from reaching part of the brain.
2. HEMORRHAGIC STROKE
The more rare, a hemorrhagic stroke, occurs when a blood vessel bursts, flooding part of the brain with too much blood while depriving other areas of adequate blood supply.
It can be the result of an AVM, or arteriovenous malformation (an abnormal cluster of blood vessels), in the brain.
Thirty percent of subarachnoid hemorrhage sufferers die before reaching the hospital. A further 25 percent die within 24 hours. And 40 percent of survivors die within a week.
Age, high blood pressure, smoking, obesity, sedentary lifestyle, diabetes, atrial fibrillation, family history, and history of a previous stroke or TIA are all risk factors for having a stroke.
SYMPTOMS OF A STROKE
- Sudden numbness or weakness of the face, arm or leg, especially on one side of the body
- Sudden confusion, trouble speaking or understanding
- Sudden trouble seeing or blurred vision in one or both eyes
- Sudden trouble walking, dizziness, loss of balance or coordination
- Sudden severe headache with no known cause
Of the roughly three out of four people who survive a stroke, many will have life-long disabilities.
This includes difficulty walking, communicating, eating, and completing everyday tasks or chores.
Both are potentially fatal, and patients require surgery or a drug called tPA (tissue plasminogen activator) within three hours to save them. THE CAUSES OF STROKE