Nutrition Notes

Neuroimaging Study Reveals Habitual Tea Drinkers Have Improved Cognitive Function

What do we already know?

Tea consumption dates back several millennia to the Shen Nong dynasty in China approximately 2700 BC. Growing evidence in scientific literature demonstrates drinking tea is beneficial to human health in various ways. More recently, it has been established that the antioxidative constituents found in tea, especially green tea, and in particular, epigallocatechin gallate (EGCg), L-theanine, as well as caffeine, have been shown to have favorable effects on mood, stress, and anxiety, and reduce the risk of cognitive decline, cancer incidence, and mortality. Further research shows that tea (including non-caffeinated herbal varieties) consumption exerts multiple health benefits in the GI tract (e.g., enhance microbiome diversity, improve satiety, anti-carcinogenic in the colon) due to the potent antioxidant and anti-inflammatory capacity from its abundance of polyphenols.    

The Study: “Habitual Tea Drinking Modulates Brain Efficiency”

The majority of studies evaluating the effects of tea consumption on health have been approached from purely neuropsychological measures, and to a much lesser extent have focused on neuroimaging that measures structure and function. Moreover, studies have shown that although the individual constituents present in tea are associated with improved cognitive abilities and reduced risk of neurocognitive decline, neuropsychological measures showed that when they were administered individually there was no significant effect, but showed synergistic effects with multi-constituent combinations of whole tea leaves themselves.

A recent study led by researchers out of the National University of Singapore that was recently published in the journal Aging explored the effects of tea consumption on brain organization by investigating both structural and functional “system-level brain networks”. Researchers recruited healthy older adults and placed them in two groups based on their tea-drinking habits, the tea-drinking group, and the non-tea drinking group. Global and regional metrics from structural and functional imaging were explored to reveal the (if any) “differential connectivity” between the two groups. Previous studies suggested that the default mode network (DMN) within the brain is a primary contributing factor involved in neurodegenerative and cognitive diseases and aging, therefore, researchers measured the interregional connectivity within the DMN, in addition to hemispheric asymmetries in structural connectivity to test the effectiveness of tea consumption. They found suppression of hemispheric asymmetry, which is associated with brain aging, in the tea-drinking group and more symmetrical structural connectivity compared to the non-tea drinking group who exhibited significant leftward asymmetry. Furthermore, the results showed stronger functional connectivity between regions of the DMN in the tea-drinking group, which is associated with improved engagement in the preparation of task implementation. According to the scientists, these results provide “the first compelling evidence that tea drinking positively contributes to brain structure making network organization more efficient” and “suggest that drinking tea regularly has a protective effect against age-related cognitive decline in brain organization”.

Clinical Application

Unfortunately, the rates of neurodegenerative disease in the U.S. is climbing at a rapid rate. It is well-established in the literature that dietary and lifestyle factors play a crucial role in the development of such diseases. Therefore, educating patients on the importance of incorporating brain-healthy foods and beverages into their daily diet is of utmost importance. Aside from following a more Mediterranean-style diet that incorporates antioxidant-rich, colorful foods like berries, olive oil, leafy greens, and nuts and seeds, adding a cup or two of high-quality tea daily is an easy way for patients to boost their overall polyphenol intake.

For patients who need the caffeine boost in the morning, and/or who experience that mid-afternoon slump and need a “pick-me-up”, suggest that they consider opting in for a cup of green or black tea instead of their typical cup ‘o Joe. And likewise, patients who may feel they need three or four (or more) cups of coffee may consider limiting their intake to one cup and then switching over to green, black, or herbal teas as to not exceed established caffeine intake recommendations and increase their exposure to constituents found in the different tea varieties that have been shown to exert positive health benefits, such as decreased stress, improved alertness, and sustained attention and memory. For those with more complex conditions that are inflammatory in nature, a broad-spectrum antioxidant supplement that contains both classic (e.g., vitamin C) and novel ingredients (e.g., EGCg, tocotrienols) among other anti-inflammatory compounds may be a great addition to combat further oxidative damage and stress.