Tea is generally considered good for you, but there hasn’t been a lot of science behind that claim.
Now a team of scientists at National University of Singapore Yong Loo Lin School of Medicine has put a bit of muscle into the discussion.
However, experts interviewed by Healthline say there are still a lot of unanswered questions.
In the Singapore study published in the Journal of Nutrition, Health and Aging, the research team concluded that drinking tea regularly lowered the risk for cognitive impairment in older adults by 50 percent.
Furthermore, this rate of reduced cognitive decline increased by as much as 86 percent for people who carry the APOE e4 gene (apolipoprotein E), which puts them genetically at higher risk of developing Alzheimer’s disease.
Feng Lei, an assistant professor in the department of psychological medicine at the Singapore school, pointed out that the bioactive compounds in tea leaves, including catechins, theaflavins, thearubigins, and L-theanine, have anti-inflammatory and antioxidant potential that create this long-term benefit.
These and other bioactive properties also protect the brain from vascular damage and neurodegeneration, according to Lei.
“Our findings have important implications for dementia prevention,” Lei said in a press release. “Despite high-quality drug trials, effective pharmacological therapy for neurocognitive disorders, such as dementia, remains elusive and current prevention strategies are far from satisfactory.”
This discovery, he said, might provide an easy, inexpensive health benefit.
“Tea is one of the most widely consumed beverages in the world. The data from our study suggest that a simple and inexpensive lifestyle measure, such as daily tea drinking, can reduce a person’s risk for developing neurocognitive disorders in late life,” he said.
Conclusions and questions
In order to determine the association between tea consumption habits and the incidence of neurocognitive disorders, the investigative team collected tea consumption data for 957 community-living Chinese adults aged 55 years or older from 2003 to 2005.
They also gathered information on cases of neurocognitive disorders from 2006 to 2010, noting that all the participants were cognitively intact at baseline when the study began.
Lei and colleagues identified 72 incident cases of neurocognitive disorders within the group. Independent of other risk factors, consumption of both green tea and black/oolong tea reduced the risk of incidents linked to neurocognitive disorders.
The tea study has been met with mild interest and a lot of questions.
According to James A. Hendrix, PhD, director of global science initiatives at the Alzheimer’s Association, a lot more work needs to be done on the subject.
“I’m always a little skeptical of associative studies,” he told Healthline.
Because two things occur at the same time does not prove one caused the other, he noted.
“We need independent research on this subject. If they find a similar link, maybe we should investigate,” he said.
Hendrix recalled the results from tests of other dietary supplements, notably vitamins “that were touted as a treatment. That was disappointing.”
Another issue with the study, Hendrix said, is that it was conducted on a homogeneous population.
Lei acknowledged this in a press release: “While the study was conducted on Chinese elderly, the results could apply to other races as well.”
Furthermore, the data was gathered based on self-reports, which Hendrix noted was a weakness. “People were asked how much tea they drank. They weren’t monitored by a third party,” he said. “That creates issues.”
The study also raised other questions.
How long does a person have to drink tea to get the potential benefits?
What happens if you are not a lifetime tea drinker, but start at age 50? Or 60?
And how much tea is enough? One cup? Five?
“It’s important to recognize how long one has been doing this,” Hendrix said.
He cited a Finnish study of people with dementia who showed a slowing of symptoms when they engaged in regular exercise.
He suggested the same issue around food and drink. If you don’t start early, do you have a higher risk?
“The Mediterranean diet is beneficial to the cardiovascular system,” Hendrix said. “And what’s good for the heart is good for the brain.”
“We don’t know if it works if you’ve eaten a bad Western diet until you’re 75 and then switch to a healthier one,” he said. “But it can’t hurt.”
What can you do?
A recent poll showed that for the first time more people worry about getting dementia than cancer.
And that leads to Hendrix’s best advice: Develop a healthy lifestyle. Eat a balanced diet. Exercise. Quit smoking.
“It’s unlikely the solution will be a single substance,” he said.
Susan Weiner doesn’t think that tea is a magic pill either.
The nutritionist and registered dietician called the study interesting, but she’d like to see more study.
“More research is needed,” she told Healthline, “but it's promising due to the antioxidant properties, which may have a very positive impact on cognitive function.”
On a more mundane level, she said, “tea can be a delicious addition to your diet. Also … when no sweeteners are added they are calorie-free.”