An analysis of more than 30,000 adults found that most people fail to reach the flavanol intake associated with cardiovascular benefits, even when they meet standard fruit and vegetable recommendations.
By yourNEWS Media Newsroom
Green tea contains more flavanols than apples, blueberries and strawberries, according to a new study that examined whether common diets provide enough of the plant compounds to reach levels associated with cardiovascular benefits.
The study, published in the journal Food and Function, ranked green tea fourth among commonly consumed foods and beverages for flavanol content.
Researchers analyzed dietary information from more than 30,000 adults in the United Kingdom and the United States, comparing participants’ intake with a daily target of 500 milligrams of flavanols.
That threshold was associated with cardiovascular benefits in the COSMOS trial, a major U.S. study in which flavanol supplementation was linked to a 27% lower risk of death from cardiovascular disease.
The new analysis found that fewer than one-quarter of adults who met conventional fruit and vegetable recommendations also consumed at least 500 milligrams of flavanols per day.
Researchers concluded that following current dietary guidelines does not necessarily provide the amount of flavanols associated with improved cardiovascular outcomes.
Green tea, black tea, oolong tea, matcha, apples and berries were identified as concentrated dietary sources of the compounds.
Expert Cautions Against Replacing Fruit With Tea
Although green tea ranked above several fruits in flavanol concentration, nutrition experts cautioned that the findings do not mean tea should replace whole fruits and vegetables.
Registered dietitian Nichola Ludlam-Raine told the Daily Mail that direct comparisons between a beverage and a piece of fruit overlook important nutritional differences.
“While a cup of green tea may contain more flavanols than an apple, apples also provide fiber, Vitamin C and a range of other nutrients, as well as contributing to your five-a-day,” Ludlam-Raine said.
She said green tea can complement a healthy diet but should not be treated as a substitute for fruit or vegetables.
Whole fruits provide combinations of fiber, vitamins, minerals and other plant compounds that cannot be fully reproduced in a beverage.
Apples, berries and avocados have also been associated with improved metabolic health and a lower risk of Type 2 diabetes. Reports have highlighted their possible roles in supporting healthier blood pressure and improved insulin sensitivity.
Ludlam-Raine urged consumers to focus on dietary variety rather than selecting one food or drink solely because it contains a higher concentration of a particular compound.
Catechins and L-Theanine Contribute to Green Tea’s Profile
Green tea contains several types of catechins, including epigallocatechin gallate, commonly known as EGCG. It also contains L-theanine, an amino acid associated with calmness and focused attention.
Green tea leaves are steamed or heated in pans shortly after harvesting, limiting oxidation and helping preserve catechins and other plant compounds.
Black tea undergoes more oxidation during processing, resulting in a different phytochemical composition.
Green tea extracts generally contain higher levels of catechins than black or oolong tea extracts, according to Jane Higdon’s book, Evidence-Based Approach to Phytochemicals and Other Dietary Factors.
Black tea extracts, by comparison, tend to contain more theaflavins and thearubigins.
Catechins act as antioxidants and have been studied for possible effects on oxidative stress, inflammation, cholesterol and blood sugar.
L-theanine has been associated with relaxed concentration and may help moderate some of caffeine’s stimulating or jittery effects.
“For most healthy adults, two to four cups of green tea a day can comfortably fit into a balanced diet,” Ludlam-Raine said.
She said that amount can provide a meaningful source of polyphenols without exposing most people to excessive caffeine.
Green Tea Contains Less Caffeine Than Coffee
A typical cup of green tea contains approximately 30 to 50 milligrams of caffeine, depending on the type of tea and the way it is brewed.
A standard cup of coffee generally contains between 80 and 100 milligrams.
People who are sensitive to caffeine may want to avoid green tea late in the day because it can still interfere with sleep.
Pregnant or breastfeeding women are generally advised to keep total daily caffeine consumption below 200 milligrams.
Matcha, which is made by grinding whole green tea leaves into powder, usually contains higher concentrations of catechins and other plant compounds than conventionally brewed green tea.
Because the entire powdered leaf is consumed, matcha also generally contains more caffeine than ordinary green tea, although it typically provides less than coffee.
Ludlam-Raine warned that many matcha drinks sold in coffee shops contain added sugar, flavored syrups or sweetened milk.
Those additions can substantially increase calories and sugar, reducing the drink’s overall nutritional value.
Weight-Loss Benefits Appear Limited
Green tea is frequently marketed as a drink that accelerates metabolism or promotes fat burning, but evidence for meaningful weight loss remains weak.
“The evidence suggests green tea may have a very small effect on metabolism and fat oxidation, largely due to its combination of caffeine and catechins,” Ludlam-Raine said.
She said any resulting effect on body weight would likely be modest and insufficient to produce substantial changes without broader dietary and lifestyle measures.
A 2012 Cochrane Review found that green tea preparations may produce a very small amount of weight loss among adults who are overweight or obese.
The effect was not statistically significant and was considered unlikely to be clinically meaningful.
The review also found no evidence that green tea helped people maintain weight loss.
Ludlam-Raine said a balanced diet, regular exercise, sufficient sleep and sustainable habits that create a calorie deficit are much more influential than simply adding green tea to a person’s routine.
Concentrated Supplements Carry Greater Risks
Green tea brewed from leaves is generally considered safe when consumed in moderate amounts, but concentrated extracts can expose users to much larger doses of catechins.
“Green tea extract supplements can contain highly concentrated amounts of catechins that you would never get from drinking tea alone,” Ludlam-Raine said.
High-dose green tea extract supplements have been associated with liver injury in some reports.
Ludlam-Raine said such products are unnecessary for most people and that rare cases of liver damage have been linked to their use.
The risks associated with extracts do not necessarily apply to moderate consumption of traditionally brewed green tea.
Research has also examined whether flavanol-rich foods such as tea and cocoa can support cardiovascular health.
A major meta-analysis cited by NaturalNews.com reported that flavanol-rich foods could lower blood pressure by amounts comparable to some medications.
Ludlam-Raine nevertheless cautioned against treating matcha or green tea as a miracle product.
Matcha may provide a higher concentration of catechins and related compounds than standard brewed tea, but it does not supply the fiber, vitamins and minerals found in whole fruit.
The findings suggest that green tea can be a valuable source of flavanols within a varied diet, particularly because relatively few adults consume the 500-milligram daily amount associated with cardiovascular benefits.
They do not support replacing fruits, vegetables or other nutrient-rich foods with tea.
For most healthy adults, moderate consumption of unsweetened green tea may increase flavanol intake while keeping caffeine relatively low, but broader eating patterns remain more important than any single beverage.
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