This week, yet another study was published in which tea makes its appearance.
Should we be excited? Should coffee drinkers throw up their hands and join the tea cohort? Can we use this as an excuse to buy that pricy tea we’ve been eying?
Well, like the tea-longevity study that I recently looked at (Drink Tea, Live Longer?), this too is an observational study with much of the data self-reported by the research participants, which necessarily limits the results’ conclusiveness.
But here’s the fun part to me:
That tea-longevity study (published January 8) by Xinyan Wang and team suggested that tea drinking was linked to a longer life, with lower incidences of heart attacks, death from heart disease, and stroke. The scientists noted, however, that:
tea consumption is part of a cultural heritage, and its health effects might be confounded by other eating and drinking patterns, for example, consumption of other flavonoid-rich foods or beverages like coffee. [emphasis mine]
Practically as an answer, this latest study by Thomas Holland and colleagues, published online yesterday, focuses on flavonoid-rich foods and beverages!
Okay, so Holland et al. concentrate on Alzheimer dementia rather than cardiac issues and mortality but still, is it the tea or is it anything containing flavonoids?
Anyway, in researching Alzheimer dementia, the team followed over 900 participants, mostly women, with a mean age of 82.1 years, concentrating on flavonol consumption and how that may relate to the development of dementia.
Working backwards, flavonols are a type of flavonoid, flavonoids are a type of polyphenol, and polyphenols are organic chemicals found in plants. Of the flavonoids found in food that we eat, most of them are flavonols. Importantly, they are antioxidants, meaning they react with free radicals, the unstable molecules that occur naturally in our bodies but which can cause cell damage, including damage to the neurons in our brain.
Therefore, consuming flavonoid-rich food would seem to help our health, both of body and mind, and many studies have suggested just that. So Holland’s team assessed the food that the participants reported eating, particularly those containing these flavonols, listed here with the specific flavonol-containing foods most consumed by the participants:
- kaempferol—in kale, beans, tea, spinach, broccoli
- quercetin—in tomatoes, kale, apples, tea
- myricetin—in tea, wine, kale, oranges, tomatoes
- isorhamnetin—in pears, olive oil, wine, tomato sauce
The researchers found that the participants who ingested the most flavonols also reported:
- higher levels of education
- more hours of physical activity per week
- more frequently engaging in activities that stimulate the brain
- lower rates of depression
Which begs the question, what causes what?
Do more educated people better understand the importance of a plant-based diet and thus act accordingly? Or are those who enjoy physical activity also more cognizant of their body and therefore more likely to choose healthy foods? Or does eating a better diet make a person feel better and thus better able to engage in physical activity? And just which of these operatives staves off dementia? One, some, all? You get the idea!
Even so, the effects of Alzheimer dementia are measurable to some degree, and the study did find that consuming more kaempferol, myricetin, and isorhamnetin was associated with lower rates of the dementia.
The scientists also probed whether these results were due to flavonols having a protective effect on cardiac health and diabetes, or if other nutrients were responsible, but they found nothing to support those suppositions. Rather, they (Holland et al. 2020:5) assert that:
the association of total flavonols with Alzheimer dementia was statistically significant.
So, can we get excited? Can we use this as an excuse to buy more tea?!
Well, even though a first glance at this study might suggest we should consume more tea and kale because they made the cut for kaempferol and myricetin, that’s not the entire truth.
Kale and tea aren’t necessarily the foods that contain the most of these particular flavonols. Rather, the listed foods/beverages for each flavonol were “the top food item contributors to the individual flavonols” that were self-reported by the participants in the study. Kale and tea happened to be what people were consuming (or said they were consuming).
But tea does have lots of flavonols, that is true—although nowhere in the publication did I see how “tea” was defined. Camellia sinensis? And if so, black or green tea, because they contain different amounts of flavonols. Or herbal or fruit or rooibos “tea”? Which all contain flavonols, of course, to varying degrees.
The upshot? Does tea help prevent the Alzheimer form of dementia?
This is another, limited, study, but it continues to build the case that we definitely should be eating more fruit and veggies, or at least those containing certain flavonols—and the flavonols found in tea are among those that seem beneficial.
I’m filling my teacup right now, . . . but did you notice that wine also made the list?! Hmmmm.
Sources: (1) “Tea consumption and the risk of atherosclerotic cardiovascular disease and all-cause mortality: The China-PAR project,” by Xinyan Wang et al., European Journal of Preventive Cardiology, 1/8/2020; (2) “Dietary flavonoid and risk of Alzheimer dementia,” by Thomas M. Holland et al., American Academy of Neurology, online pre-publication 1/29/2020. Print version will be: Neurology 94(16), 4/21/20.