Consumption of coffee and tea and risk of developing stroke, dementia, and poststroke dementia

Our study showed that there was an interaction between coffee and tea that associated with stroke and dementia. There are several mechanisms whereby the combination of coffee and tea may be related to stroke and dementia. First, coffee is the primary source of caffeine and contains phenolics and other bioactive compounds with potential beneficial health effects. Likewise, tea contains caffeine, catechin polyphenols, and flavonoids, which have been reported to have neuroprotective roles such as antioxidative stress, anti-inflammation, inhibition of amyloid-beta aggregation, and antiapoptosis [18,50,51]. Coffee and tea are distinct beverages with both overlapping and different contents [14]. One potential mechanism may be related to the combined protective role of the different antioxidant and other biological contents in these 2 beverages [16]. Second, coffee and tea have a specific polyphenolic content, characterized by hydroxycinnamic acids in the former, and catechins in the latter, which have demonstrated potential benefits in ameliorating endothelial function, insulin resistance, and anti-inflammation, and have different target molecules [52]; thereby, the specific polyphenolic contents of coffee and tea may play a combined protective role in the pathogenesis of stroke and dementia. Third, both coffee and tea were related to lower cardiometabolic risks, including type 2 diabetes, hypertension, and CAD [25,48,49]. Thus, consuming the 2 beverages in combination may have a joint health benefit for preventing the risk of stroke and dementia. Fourth, the interaction between coffee and tea drinking for both stroke and dementia may have arisen due to chance. Finally, consumption of coffee and tea may jointly modulate certain cytokine activation [53–55]. Further validation in animal experiments is warranted to examine coffee and tea’s potential joint associations on dementia... More here.

This is a 'very' long study and it only adds to my belief that there is no amount of coffee that is unhealthy!