From the Abstract:
Tea consumption, especially green tea, is associated with significantly reduced risks for stroke, diabetes, depression, and improved levels of glucose, cholesterol, abdominal obesity and blood pressure. Habitual coffee consumption in large epidemiological studies is associated with reduced mortality, both for all-cause and cardiovascular deaths. In addition, coffee intake is associated with risks of heart failure, stroke, diabetes mellitus, and some cancers in an inverse dose-dependent fashion. Surprisingly, coffee is associated with neutral to reduced risks for both atrial and ventricular arrhythmias. However, caffeine at high doses can increase anxiety, insomnia, calcium loss, and possibly the risk of fractures.
Coffee and tea can generally be recommended as health-promoting additions to an adult diet. Adequate dietary calcium intake may be particularly important for tea and coffee drinkers.
Quotes from the Article about Tea:
“The authors concluded that people who drink at least four cups of tea per day may have a 16% lower risk of developing type 2 diabetes than nontea drinkers.”
“The results were replicated in another meta-analysis  that included 22 trials and showed that green tea consumption was associated with significant reduction in total and LDL cholesterol levels with no significant effect on HDL and triglyceride levels.”
“In NHANES study, hot tea consumption was inversely associated with obesity, mean waist circumference, and inflammatory markers, but interestingly enough, the association was reversed for cold tea… …plausible that the increased antioxidant content, lower sugar content, and more favourable metabolic effects of hot tea make it more effective at burning off abdominal fat and reducing inflammation than cold tea…”
“…individuals consuming at least four cups green tea per day had a 51% significantly lower likelihood of having depressive symptoms than participants consuming one cup/day or less of green tea…”
Quotes about Coffee:
“both all-cause and heart-related, with the lowest risks noted among those individuals chronically consuming about two to four cups/day”
“A very recent observational study suggested that high coffee consumption (>28 cups/week) was associated with increased all-cause mortality”
“On the basis of this study , it seems appropriate to suggest that people avoid heavy coffee consumption (more than four cups/day).”
Historically, I haven’t been a big tea person, but I’ve been drinking coffee for years. I actually thought the coffee might be a problem, so a few years back I gave it up for a couple weeks before reading that coffee is generally considered healthy these days; however I was wondering if I might be getting too much of a good thing, so I figured I’d do some more research. I was especially interested in researching this since I developed my new interest in intermittent fasting, for which just about everyone asks, “What about coffee?” Nobody has yet asked me, “What about tea?” with regards to fasting, apparently because we’re in ‘Merica.’ Even so, I thought the comparisons were interesting.
There was an interesting finding in the paper stating that people who consume hot tea had lesser abdominal fat and inflammatory markers, while the opposite was found in cold tea drinkers. The authors thought the temperature/type of tea may or may not be the reason for these opposing findings, but instead thought that it may be because cold tea drinkers were more likely to add sugar to their drinks. In conclusion, sugar is likely bad enough to offset tea’s goodness, which was also noted in the paper regarding coffee and diabetes, so it’s probably a good idea that I gave up the Coffee-mate.
I think the tricky part in adequately dosing your beverage for health, is determining how much a cup is. It’s not like they accurately dosed out coffee and tea and held people in a biosphere to see how long they lived, rather in the papers reviewed often went on people’s reports. One thing that came to my attention when trying to accurately measure out a cup of coffee, is that all mugs are different. My coffee mug holds 413 ml, which is about 1.75 8 oz cups.
That part I suspected, but what I didn’t expect was that cup indicator marks on my Mr. Coffee machine weren’t even close. My coffee pot measured four cups of liquid, reading as six cups! To my surprise, when my office staff told me I was regularly drinking 11 cups per day (which is probably bad) I was in fact only drinking seven cups (which is probably bad, but not as bad). The revelation made me think that the amounts of both coffee and tea studies are likely all somewhat suspect, as I have my doubts that anyone surveyed actually pulled out a graduated cylinder and measured what they were actually consuming.
Still, the general recommendation of four plus cups of tea per day being ideal was confirmed by several studies, with no data given regarding an upper limit of health going much beyond that as found with coffee when you went beyond four cups. According to wikipedia, Health Canada recommends no more than 2.5 mg/kg body weight of caffeine for adults which could be used as a guide, but even then you run into questions which vary; “how much caffeine is in a given type of coffee or tea, and how it is prepared?”
So the best take home message for proper dosage now appears to be four plus ‘cups’ of tea per day, with green tea perhaps being best, while coffee being two to four cups, but not more being somewhere close to ideal. There was no data given regarding a combination, but the mechanisms of action cited were not identical, so I plan to switch it up.
As always, if you have any further questions or need for clarifications, please don’t hesitate to ask. Being aware that some of my blog ideas are contentious and occasionally a bit out of the field of my expertise, I encourage my readers to come forth with any questions/comments that are of interest or concern. Your comments are valued and welcomed.
Chad Reilly is a licensed physical therapist, located in North Phoenix, practicing science based medicine with treatment protocols unique and effective enough to proudly serve patients from Phoenix, Scottsdale, Mesa, Chandler, Tempe, Peoria, and Glendale.