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Dean Pomerleau

Coffee Once Again Shown to be Good For You

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[Note: This is my first thread on the new "General Health & Longevity" forum - thanks for making it!]

 

Yet another study has found drinking a surprisingly large number of cups of coffee per day to be health promoting.

 

This new study [1] in the Journal Circulation by Harvard researchers (press release, including a video, here) used epidemiological data from 74,890 women in the Nurses' Health Study, 93,054 women in the Nurses' Health Study 2, and 40,557 men in the Health Professionals Follow-up Study. Participants completed food questionnaires every four years during an average follow-up period of 22.5 years, providing researchers with coffee consumption data.

 

There appeared to be a shallow, U-shaped mortality curve for coffee drinking, with the greatest reduction in non-smoker mortality (15%) among those who consumed 3-5 cups of coffee per day. Greater than 5 cups per day reduced all-cause mortality by slightly less (12%) when compared to never-drinkers. Both caffeinated and decaf coffee was found to reduce mortality. The causes of death that were significantly lower among coffee drinkers were cardiovascular disease, neurological diseases, and suicide.

 

This Harvard study is in agreement with another large, epidemiological study [2] from earlier this year which found an even greater reduction in all-cause and cause-specific morality among a Japanese cohort of 90,000 people followed for 19 years. It too found a sweet spot around 3-4 cups per day, with a reduction in all-cause mortality of 24%.

 

So once again, coffee is found to be good for you. But remember not to drink it too hot, and be sure to filter it, preferably with a paper filter.

 

----------

[1] Circulation November 16, 2015, Published online before print 

doi: 10.1161/CIRCULATIONAHA.115.017341

 

Association of Coffee Consumption with Total and Cause-Specific Mortality in Three Large Prospective Cohorts

 

Ming Ding1; Ambika Satija1; Shilpa N. Bhupathiraju1; Yang Hu1; Qi Sun2; Jiali Han3; Esther Lopez-Garcia4; Walter Willett2; Rob M. van Dam5; Frank B. Hu2*
 
Abstract
 
Background—The association between consumption of caffeinated and decaffeinated coffee and risk of mortality remains inconclusive.
 
Methods and Results—We examined the associations of consumption of total, caffeinated, and decaffeinated coffee with risk of subsequent total and cause-specific mortality among 74,890 women in the Nurses' Health Study (NHS), 93,054 women in the NHS 2, and 40,557 men in the Health Professionals Follow-up Study. Coffee consumption was assessed at baseline using a semi-quantitative food frequency questionnaire. During 4,690,072 person-years of follow-up, 19,524 women and 12,432 men died. Consumption of total, caffeinated, and decaffeinated coffee were non-linearly associated with mortality. Compared to non-drinkers, coffee consumption one to five cups/d was associated with lower risk of mortality, while coffee consumption more than five cups/d was not associated with risk of mortality. However, when restricting to never smokers, compared to non-drinkers, the HRs of mortality were 0.94 (0.89 to 0.99) for ≤ 1 cup/d, 0.92 (0.87 to 0.97) for 1.1-3 cups/d, 0.85 (0.79 to 0.92) for 3.1-5 cups/d, and 0.88 (0.78 to 0.99) for > 5 cups/d (p for non-linearity = 0.32; p for trend < 0.001). Significant inverse associations were observed for caffeinated (p for trend < 0.001) and decaffeinated coffee (p for trend = 0.022). Significant inverse associations were observed between coffee consumption and deaths due to cardiovascular disease, neurological diseases, and suicide. No significant association between coffee consumption and total cancer mortality was found.
 
Conclusions—Higher consumption of total coffee, caffeinated coffee, and decaffeinated coffee was associated with lower risk of total mortality.
 

PMID: 26572796

 

------------

[2] Am J Clin Nutr. 2015 May;101(5):1029-37. doi: 10.3945/ajcn.114.104273. Epub 2015

Mar 11.

Association of coffee intake with total and cause-specific mortality in a
Japanese population: the Japan Public Health Center-based Prospective Study.

Saito E(1), Inoue M(1), Sawada N(1), Shimazu T(1), Yamaji T(1), Iwasaki M(1),
Sasazuki S(1), Noda M(1), Iso H(1), Tsugane S(1).


BACKGROUND: Despite the rising consumption of coffee worldwide, few prospective
cohort studies assessed the association of coffee intake with mortality including
total and major causes of death.
OBJECTIVE: We aimed to investigate the association between habitual coffee
drinking and mortality from all causes, cancer, heart disease, cerebrovascular
disease, respiratory disease, injuries, and other causes of death in a
large-scale, population-based cohort study in Japan.
DESIGN: We studied 90,914 Japanese persons aged between 40 and 69 y without a
history of cancer, cerebrovascular disease, or ischemic heart disease at the time
of the baseline study. Subjects were followed up for an average of 18.7 y, during
which 12,874 total deaths were reported. The association between coffee intake
and risk of total and cause-specific mortality was assessed by using a Cox
proportional hazards regression model with adjustment for potential confounders.
RESULTS: We showed an inverse association between coffee intake and total
mortality in both men and women. HRs (95% CIs) for total death in subjects who
consumed coffee compared with those who never drank coffee were 0.91 (0.86-0.95)
for <1 cup/d, 0.85 (0.81-0.90) for 1-2 cups/d, 0.76 (0.70-0.83) for 3-4 cups/d,
and 0.85 (0.75-0.98) for >5 cups/d (P-trend < 0.001). Coffee was inversely
associated with mortality from heart disease, cerebrovascular disease, and
respiratory disease.
CONCLUSION: With this prospective study, we suggest that the habitual intake of
coffee is associated with lower risk of total mortality and 3 leading causes of
death in Japan.

© 2015 American Society for Nutrition.

PMID: 25762807

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OK - so 3-5 'cups' of coffee per day is the 'optimal' dose for health and longevity according to several epidemiological studies. But what the heck is a 'cup' of coffee, anyway?

 

Bizarrely, a standardized 'cup' of coffee is considered to be 6oz (= 177g) rather than the standard measuring cup (8oz).

 

But that is 6oz of liquid coffee. The amount of health-promoting polyphenols in that liquid coffee will vary depending on how it's brewed, how much ground coffee is used to brew it, etc.

 

So how much ground coffee is typically used to brew a standard cup? According to The Coffee FAQ, the standard is about 10g of ground coffee / 6oz cup, which equates to about 2 tablespoons.

 

So, if we're shooting for ~4 standardized (6oz) cups of coffee per day, that equates to about 40g, or conveniently, about 1/2 cup (that is - 1/2 a standard measuring cup's worth), of ground coffee per day, independent (more or less) of the amount of water used to brew it.

 

I've always wanted to know that. Now I do, and you do too!

 

--Dean

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Dean, thanks for the posts -- both of them! I've been drinking coldbrew coffee made with 30 g of finely ground light roast every day, all at once, in the morning. I read somewhere that caffeine extraction is a bit less efficient with coldbrew, so I've been assuming, for the purposes of various sleep experiments, that that equates to maybe 25 g of hot brew, but that's just a guess. But it looks like the caffeine wasn't relevant to the health benefits in the study you cite. That's a little weird, since many studies link morbidity and mortality reduction in coffee drinkers to the caffeine. And there are lots of mechanistic explanations that point to caffeine as being beneficial.

 

Click the "Review" filter on the results of a PubMed [ caffeine Alzheimer's ] search for some interesting papers.

 

Zeta

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This is from a conversation started with Dean in the Facebook group. I said:

 

As a slow caffeine metabolized I stand to gain limited benefits or may actually experience a net negative effect from higher intakes. I love coffee so I generally drink a lot of decaf to increase my exposure to the non -caffeine photochemical and possibly the fatty acids which presumably account for a large portion of the benefit. Though caffeine and the other phytochemicals have independent and synergistic effects. Thankfully drinking French press coffee doesn't seem to appreciably negatively affect my lipids.

 

 

In terms of genotypes, only rs762551(A;A) individuals are considered fast metabolizers. Individuals who are rs762551(A;C) heterozygotes or rs762551(C;C) homozygotes are both considered slow metabolizers.

 

23andMe tells me I'm a slow-metabolizer and it definitely explains my sensitivity to caffeine, chocolate, and similar stimulants. The SNPedia link provides some studies showing differences in the caffeine-metabolizing CYP1A2 enzyme (fast vs. slow metabolism) modify the risk for various cancers (possibly because CYP1A2 also metabolizes estrogen, but I haven't read much into this) and dementias, and makes a passing mention of heart disease. I'm mostly concerned about the heart disease since the mechanism seems very straight forward and there is plenty of supporting epidemiology.

 

My understanding is that 1) caffeine seems to provide unique neurological and hepatic autophagy benefits, but in excess is overly stimulatory and increases blood pressure and related diseases, 2) the phytochemicals in coffee, tea, and chocolate provide a variety of unique benefits, 3) some health benefits are synergized by combining caffeine with phytochemicals. Over-consumption of caffeine increases blood pressure, the general stress response, disrupts sleep, etc. which all have negative health effects. So at some point the negatives of higher caffeine consumption outweigh the benefits of the increasing phtyochemical intake. Slow metabolizers experience a higher plasma caffeine concentration for any given intake, so their risk for over-consumption of caffeine is higher at relatively lower intakes.

 

As such, a given level of coffee consumption that could benefit a normal caffeine metabolizer could actually increase my risk for cardiovascular and metabolic diseases, as shown in the following (and the numerous 'similar articles' links):

 

CYP1A2 genotype modifies the association between coffee intake and the risk of hypertension.

Association of coffee consumption and CYP1A2 polymorphism with risk of impaired fasting glucose in hypertensive patients.

Coffee, CYP1A2 genotype, and risk of myocardial infarction.

Caffeine intake and CYP1A2 variants associated with high caffeine intake protect non-smokers from hypertension.

CYP1A2 genotype modifies the association between coffee intake and the risk of hypertension.

 

Interestingly, fast metabolizers may be at greater risk for low BMD with increasing coffee consumption.
Coffee consumption and CYP1A2 genotype in relation to bone mineral density of the proximal femur in elderly men and women: a cohort study.

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Thanks James. Very interesting. But I'm still skeptical that slow-metabolizers of caffeine such as yourself are necessarily at greater risk (or benefit less) from consumption of caffeine in coffee or some other source.

 

In short, from my quick read of the references you cite, it appears that the risks of caffeine consumption in either fast or slow metabolizers is primarily (if not exclusively) mediated by caffeine's tendency to increase blood pressure. These seems to be true for risk of heart attacks, and even the impaired fasting glucose study you cite is looking at hypertensive coffee consumers.

 

If this is the case, and you've got high blood pressure or a family history of high blood pressure, then sure, you may want to go easy on the caffeine since it might exacerbate your problem. 

 

But my point is that if your blood pressure is fine, as is the case with most CR practitioners, thankfully including you, it would seem the health benefits of caffeine (e.g. reduced dementia risk, reduced parkinson's risk, reduced heart disease risk, reduced all-cause mortality etc.) would be equivalently enjoyed whether you are a fast or slow metabolizer. In fact, an argument could be made that a non-hypertensive, slow-metabolizer of caffeine such as yourself could benefit more from the health promoting effects of caffeine, since the caffeine will be in your system longer and therefore have more time to 'do its magic'.

 

Do you know of studies that show caffeine (or caffeinated coffee) has deleterious effects among slow-metabolizers even after controlling for blood pressure?

 

If so, then my hypothesis that "caffeine in the absence of hypertension is perfectly fine" would clearly be invalidated.

 

But if not, than slow metabolizers who have normal blood pressure might not need or want to avoid caffeinated coffee, unless the subjective effects (e.g. jitters) are just too unpleasant to tolerate.

 

--Dean

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But my point is that if your blood pressure is fine, as is the case with most CR practitioners, thankfully including you, it would seem the health benefits of caffeine (e.g. reduced dementia risk, reduced parkinson's risk, reduced heart disease risk, reduced all-cause mortality etc.) would be equivalently enjoyed whether you are a fast or slow metabolizer. In fact, an argument could be made that a non-hypertensive, slow-metabolizer of caffeine such as yourself could benefit more from the health promoting effects of caffeine, since the caffeine will be in your system longer and therefore have more time to 'do its magic'.

 

I've thought about this, and I fully agree. My blood pressure at 105/65 is drinking mostly decaf coffee. If I drink full-caff I do notice some effect on my blood pressure, rising to maybe 115-120/70-80, so still "healthy". I mainly avoid full-caff most often because it disrupts my sleep (even after some habituation it's not as restful), sometimes gives me a mild anxiety, and mostly because it makes me scatter-brained and unfocused. This is with a cup or two. I actually tend to drink full-caff (when I do consume it at all) more often on weekends or when I have breaks from work since I'm more active and don't have to focus as much, and less stress means less potential for anxiety. I suspect the increased stress response and elevated blood pressure is due in part to the disrupted sleep.

 

Do you know of studies that show caffeine (or caffeinated coffee) has deleterious effects among slow-metabolizers even after controlling for blood pressure?

 

I honestly haven't looked, but I'm really curious. I'll look into this and see what I can find. I don't think it would help me with my sleep disruption, but it would be good to know for academic reasons.

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A Washington Post article posted online yesterday said mostly what we did above.

 

In research not cited by the advisory committee, scientists have identified at least one specific location in the genome - a single nucleotide out of roughly three billion - that determines whether a person processes caffeine quickly or slowly. And in those with the gene variant for handling caffeine slowly - roughly 50 percent of people - more coffee has been linked in separate studies to a higher risk of hypertension and heart attacks.

Even those scientists most involved in the genetics investigations were reluctant to say their case is proven - they all favor more research. Beyond saying that people with high blood pressure ought to limit themselves to no more than three cups per day, Palatini was loath to lay down any more general rules about coffee drinking.

 

The article doesn't address the potential for coffee to be fine in slow metabolizers with low blood pressure, for which I don't think there is available research to to know. I'd still guess that caffeine-disrupted sleep and potentially disrupted circadian rhythms in slow metabolizers, which are possible even with low blood pressure controlled by CR or lifestyle, could have enough of a negative influence that even moderate coffee consumption could prove detrimental over time.

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On the topic of caffeine, I feel I should relate the following experience which I found, and still do thirty years later, startling.

 

I have never found drinking coffee in the evening causes me to have trouble getting to sleep.  So I suppose I must be a fast metabolizer. 

 

Years ago, fairly frequently on weekends, I would need to drive for four hours in late evening after a couple of days of fairly ardous physical activity.  On the drive home I used coffee to make sure I stayed awake, and never had any disconcerting experiences.  But it occurred to me that perhaps I ought to take more precautions.  So I bought a bottle of Wake Up tablets, the active ingredient of which I understand to be just caffeine.  

 

I was about one-third of the way home and drinking coffee, and decided to take a Wake Up tablet to make sure I wouldn't fall asleep at the wheel.

 

Within 30 seconds of swallowing it I suddenly started to fall asleep.  It happened so quickly that it was as much as I could do to steer the vehicle off the road and apply the brake.

 

I woke up an hour later with the engine still running.

 

I have never had any experience like this before that event or since.  So it seems pretty clear that it was the caffeine that did it.

 

My point is, simply, to alert people to the seeming fact that not everyone responds to caffeine (or, at least, Wake Up pills) the same way.  I have never taken them since.  Although I suppose I could do a controlled experiment with them at a time when falling instantly to sleep would not represent any kind of risk.

 

Rodney.

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I've been drinking coldbrew coffee made with 30 g of finely ground light roast every day, all at once, in the morning. I read somewhere that caffeine extraction is a bit less efficient with coldbrew, so I've been assuming, for the purposes of various sleep experiments, that that equates to maybe 25 g of hot brew, but that's just a guess.

 

Another data point: For the first time in a while, I skipped my coldbrew coffee in the morning, and had regular coffee at a café instead. It was sumatra light roast, a somewhat large mugful (maybe 300 ml / 10 oz). I really felt buzzed (caffeine-buzzed). This makes me wonder whether my conversion factor from coldbrew to regular brew, at least for caffeine, is off. It could of course be that the coffee at the café was particularly strongly brewed, or that the buzz was from the excitement of seeing my cousin (my coffee-drinking mate that morning) for the first time in a while.

 

Has any coldbrew drinker out there had the same experience? Anyone willing to do an experiment to see if they have the same experience? I may try it again at home.

 

Zeta

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Zeta,

 

I see conflicting evidence online for cold-brew vs. hot-brew coffee caffeine content. I'd do the experiment you ask, but I don't seem to get a buzz from hot or cold coffee. I'm a fast caffeine metabolizer.

 

--Dean

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Has any coldbrew drinker out there had the same experience? Anyone willing to do an experiment to see if they have the same experience? I may try it again at home.

 

From my experience drinking Starbucks regular vs. cold brew I'd say I don't notice much difference, but I'm fairly sensitive to caffeine and my threshold for a relatively high buzz may be too low to make a good comparison. Caffeine Informer, using Starbucks website information, lists a 150 mg caffeine for 12 oz cold brew coffee and 180 mg caffeine for a 12 oz hot brewed coffee.

 

This is the best summary I could find, and falls in line with my understanding of the chemistry:

 

Does Cold Brew Coffee Have More Caffeine than Hot Coffee?

 
You know what's great about this time of year? It's cold brew coffee season. Easy to drink and addictively refreshing, it's no surprise that cold brew has become a summer drink of choice for many.
 
Cold brew is different from traditional iced coffee — which is just hot brewed coffee poured over ice — in that it's made by mixing coffee grounds and cold water and letting it sit for a much longer extraction time. But does cold brew coffee have more caffeine than hot coffee?
 
When it comes to caffeine, temperature plays a big role.
"Caffeine's solubility is primary driven by temperature, such that at higher temperatures, significantly more caffeine will dissolve in solution than at cooler temperatures," says Joseph Rivera of Coffee Chemistry. "If you are using the same brew-to-water ratios, the cold brew will definitely have less caffeine than hot."
 
In other words, you extract more caffeine when you brew coffee with hot water.
 
But it's not that simple.
Here is where things get a little bit complicated, and the answer to "Does cold brew coffee have more caffeine?" isn't exactly straightforward.
 
"One thing you need to consider is that cold brew coffee typically uses a much higher coffee-to-water ratio, anywhere between 2 to 2 1/2 times more," says Rivera.
 
"So, even though there is less caffeine extracted with the cold brew [method], the higher coffee-to-water ratio may compensate for this difference in solubility, and you may have a cold brew with equal, if not, more caffeine (although this is unlikely)."
 
And of course, temperature (and amount of coffee) aren't the only things that will affect your coffee's caffeine levels. "There are a number of variables, including time, temperature, grind size, flow rate (how fast water flows through grounds), contact time, and coffee type (arabica vs. robusta)."
 
Which means that if you are trying to consider how much your coffee brewing is affecting your caffeine levels, you have a lot to think about.
 
But let's be honest — if you were that concerned about your caffeine intake, you wouldn't be drinking coffee in the first place, now would you?

 

 

Effect of Time and Water Temperature on Caffeine Extraction from Coffee (PDF)

 

The coffee powder of 5 g was mixed with 30 mL of water at 60, 70, 80, 90 and 100°C and maintained at respective temperatures for 15 min.

 

...

The most effective temperature for caffeine extraction by water solvent was in the range from 90-100°C [194-212°F]. However, by soaking at 60°C [140°F] for 15 min, approximately 90% caffeine has been freed from coffee powder when contrasting to that of 90°C. Therefore, hot water (not boiling water) was effective enough for extracting caffeine from coffee powder.

 

...

 

It has also been observed that caffeine is easily liberated from coffee powder by boiling water even at the short time duration of 5 min, mounting to at least 93% in comparison the caffeine level at 30 min of extraction.

 

Check out "Table 2: Effect of time on caffeine extraction at 100°C" and "Table 3: Effect of water temperature on caffeine extraction at fixed time of 15 min."

 

Higher temperatures and longer brew times each increase the extraction of caffeine. This paper only compared 60-100°C, and cold brew is usually brewed using room temperature water (24°C, 70°F). It also only looked at 15 min brew time while cold brew usually takes between 18-24 hours (Starbucks says they brew for 20 hours). 

 

Caffeine is highly soluble in water, 2g/100ml at room temperature and 66g/100ml at boiling. Since there's no applicable upper limit to caffeine extraction from the amount of coffee/tea used, the question is how long it would take cold-brew to result in as much or more caffeine extraction as hot-brewed. This next tries to address this.

 

 

Effects of Temperature and Water Steeping Duration on Antioxidant Activity and Caffeine Content of Tea

 

Green tea (Pi Lo Chun), partially fermented tea (Oolong tea) and black tea (Red Jade black tea) ... was extracted by hot water and cold water treatments. One-gram tea and 50 mL hot water (90°C) were put into a glass beaker for 6 min, while in the other treatment tea was extracted by ultra-pure water in a 4°C refrigerator for 24 hrs.

...

 

As shown in Figure 5, the contents of caffeine of tea prepared with cold water steeping is lower than those with hot water steeping treatment.

 

This looks to be the most relevant comparison of hot and quick brew vs. cold and long brew. There is no data table, only the figures, which is strange. I'm unsure of the quality of this publication and the data, but it's all I could find.

 

Figure 5--"The caffeine contents of hot or cold water steeping of tea with different fermentation" shows a moderate caffeine difference between hot and cold brew for green tea (~400 vs 360 mg/L), a large difference for oolong (~380 vs. 240 mg/L), and a very large difference for black tea (~560 vs 200 mg/L).

 

 

Of course trying to find a straight answer is complicated by a lot of real-world variables...

 

Factors affecting the caffeine and polyphenol contents of black and green tea infusions. (PDF here)

 

Abstract

The effects of product and preparation variables on the in-cup chemical composition of tea extracts is of interest because the appearance and taste characteristics and the possible health effects of a tea liquor arise from the chemical components extracted from the leaf during tea preparation. A comprehensive study was therefore undertaken to determine the contributions of product and preparation variables on the total soluble solids, caffeine, and polyphenol contents of tea extracts. The results of this study show that the variety, growing environment, manufacturing conditions, and grade (particle size) of the tea leaves each influence the tea leaf and final infusion compositions. In addition, the composition of the tea infusion was shown to be influenced by whether the tea was contained in a teabag and, if so, the size and material of construction of the bag. Finally, the preparation method, including the amounts of tea and water used, infusion time, and amount of agitation, was shown to be a major determinant of the component concentrations of tea beverages as consumed. An illustration of the variation introduced by these product and preparation factors is provided by comparing solids, caffeine, and polyphenol contents of green and black tea infusions when commercial products are prepared according to the instructions given on their packaging.

 

The full-text provides a ton of good info on this, as do references 12-15. Though the references get into some serious math. For example, free full-text of:

 

Kinetics and equilibria of tea infusion: Part 9. The rates and temperature coefficients of caffeine extraction from green Chun Mee and black Assam Bukial teas.

 

The kinetics of extraction of individual flavanols and caffeine from a Japanese green tea (Sen Cha Uji Tsuyu) as a function of temperature.

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Wow - thanks James for your hard work investigating brewing methods and caffeine!

 

Although it just focused on hot brewing tea, I found study [1] you point to near the end of your post to be of particular interest. This was a useful table from the full text:

 

rcntC09.png

 

It shows the higher the "Leaf to Water Ratio" (i.e. the more tea you put in a given amount of water) the higher the concentration of soluble components of the tea (like polyphenols & caffeine) per liter of water. But the relationship is pretty linear, so you don't get more of the good stuff extracted just because you're using more water. Put another way, brewing in less water simple extracts the same amount (more or less) of the 'good stuff' in tea (and presumably coffee as well) - it is just more concentrated. I've always suspected that, but its good to see confirmed.

 

It also shows that the longer you steep the tea in hot water, the more of the soluble components get extracted. Again, not surprising. Here are two more helpful figures from [1]:

 

5Rjb6dw.png

 

As you can see from the top graph, extraction of 'good stuff' (soluble solids) continues to increase out to a 3min steep time, but it is asymptoting out, suggesting hot brewing longer than 3min isn't of much benefit. Strangely, I couldn't find the temperature at which this brewing test was done. The bottom table shows that at least for hot brewing, the caffeine comes out of the tea faster than the polyphenols, so a longer brew time (say 5min vs. 2min) appears to significantly increase the amount of polyphenols, without bumping up the caffeine too much.

 

I wish there was more info on cold brewing, since I like the taste and convenience better for my tea, coffee and cacao preparation (which I combine). I too have noticed digging around on the web what one of the websites you point to mentions, namely that cold-brewed coffee typically has a higher ground coffee to water ratio. I've taken that to heart, along with a longer cold brew time (~20h vs. 12h) and doing it on the counter, rather than in the fridge, in hopes of maximizing the potency of the brew.

 

But now, thinking back on all this data, and on your last reference [2], which suggests that the amount of the various catechins in green tea that are extracted at various temperatures depends on their molecular weight, makes me think there could be some minimum temperature required to effectively dislodge some of them from the leaf matrix. It is just a hunch, but it seems consistent with my (admittedly limited) understanding of [2]. At the very least the factors affecting the extraction of solids during hot brewing is extremely complicated.

 

So...

 

Since the effectiveness of extraction of polyphenols and caffeine from cold brewing tea / coffee is not well studied or understood (much less cacao...), I'm probably going to start doing a brief hot brew of a portion of my tea/coffee/cacao concoction at the end of the cold brewing process, just to make sure I'm getting the maximum extraction, and not missing out on polyphenols that are known to be well extracted via hot brewing. Call me obsessive...

 

Thanks again James!

 

--Dean

 

----

[1] J Agric Food Chem. 2001 Nov;49(11):5340-7.

Factors affecting the caffeine and polyphenol contents of black and green tea
infusions.

Astill C(1), Birch MR, Dacombe C, Humphrey PG, Martin PT.

Author information:
(1)Unilever Research Colworth, Colworth House, Sharnbrook, Bedford MK44 1LQ,
United Kingdom. conrad.astill@unilever.com

The effects of product and preparation variables on the in-cup chemical
composition of tea extracts is of interest because the appearance and taste
characteristics and the possible health effects of a tea liquor arise from the
chemical components extracted from the leaf during tea preparation. A

comprehensive study was therefore undertaken to determine the contributions of
product and preparation variables on the total soluble solids, caffeine, and
polyphenol contents of tea extracts. The results of this study show that the
variety, growing environment, manufacturing conditions, and grade (particle size)
of the tea leaves each influence the tea leaf and final infusion compositions. In
addition, the composition of the tea infusion was shown to be influenced by
whether the tea was contained in a teabag and, if so, the size and material of
construction of the bag. Finally, the preparation method, including the amounts
of tea and water used, infusion time, and amount of agitation, was shown to be a
major determinant of the component concentrations of tea beverages as consumed.
An illustration of the variation introduced by these product and preparation
factors is provided by comparing solids, caffeine, and polyphenol contents of
green and black tea infusions when commercial products are prepared according to
the instructions given on their packaging.

PMID: 11714326 

-------------

[2] Food Chemistry Volume 50, Issue 1, 1994, Pages 19-23 doi:10.1016/0308-8146(94)90086-8

 
The kinetics of extraction of individual flavanols and caffeine from a Japanese green tea (Sen Cha Uji Tsuyu) as a function of temperature
Author links open the overlay panel. Numbers correspond to the affiliation list which can be exposed by using the show more link.
 
William E. Price, John C. Spitzer
 
Abstract
 
Rates of infusion for the four major tea flavanols from a Japanese green tea have been measured for the first time. The results indicate that the ungallated epicatechin and epigallocatechin infuse faster than the gallated flavanols epicatechin gallate and epigallocatechin gallate. The infusion rate is shown to be related to the inverse of the square root of the mass of the molecule. This gives support to the idea that the rate-determining step of the infusion process is a diffusive one. The temperature-dependence of the infusion of the four flavanols yields activation energies of 30 and 50 kJ/mol. In addition, rates of infusion of caffeine from the green tea and its temperature-dependence were investigated. These results indicate that the caffeine infusion rate and the activation energy are significantly larger than for the four flavanols and also larger than for caffeine infusion from black teas. This latter aspect is discussed in terms of differences in manufacturing techniques between black and green tea.

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It also shows that the longer you steep the tea in hot water, the more of the soluble components get extracted. Again, not surprising. Here are two more helpful figures from [1]:

 

 

 

5Rjb6dw.png

As you can see from the top graph, extraction of 'good stuff' (soluble solids) continues to increase out to a 3min steep time, but it is asymptoting out, suggesting hot brewing longer than 3min isn't of much benefit. Strangely, I couldn't find the temperature at which this brewing test was done. The bottom table shows that at least for hot brewing, the caffeine comes out of the tea faster than the polyphenols, so a longer brew time (say 5min vs. 2min) appears to significantly increase the amount of polyphenols, without bumping up the caffeine too much.

These figures and data are really interesting. I would be interested in reading the full article. ( note added: I just find the reference of james to the full article) I am wondering what will be the percentage of caffeine and catechins in the case of a second or third brew. I practise Taijiquan and my Chinese teacher said once that in China traditionally they believe that the second brew is the best and third brew is like the first. I often do a second brew of my tea (in the first brew about 5 min as brew time). If I interpret correctly the table 7 after 300 s remains only 18.4% of catechins ?! Is this a case of "The unverified conventional wisdom is almost invariably mistaken" ? :) Edited by Cloud

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OK - so 3-5 'cups' of coffee per day is the 'optimal' dose for health and longevity according to several epidemiological studies. But what the heck is a 'cup' of coffee, anyway?

 

Bizarrely, a standardized 'cup' of coffee is considered to be 6oz (=177g) rather than the standard measuring cup (8oz).

Dean,

 

Thanks for pointing that out. I had assumed a cup was a cup was a cup ...

 

Dean wrote:

So how much ground coffee is typically used to brew a standard cup?

According to The Coffee FAQ, the standard is about 10g of ground coffee / 6oz cup, which equates to about 2 tablespoons.

 

Thanks for that info.

 

So, if we're shooting for ~4 standardized (6oz) cups of coffee per day, that equates to about 40g, or conveniently, about 1/2 cup (that is - 1/2 a standard measuring cup's worth), of ground coffee per day, independent (more or less) of the amount of water used to brew it.

 

I've always wanted to know that. Now I do, and you do too!

 

Also good to know. This short post was well worth reading.

 

The amount of health-promoting polyphenols in that liquid coffee will vary depending on how it's brewed ...

 

This might not be the right place to parade my ignorance around, but Google searches didn't enlighten me, so here goes.

 

Catechins are antioxidants (a good thing), but they are also phenols.

 

Phenols don't sound that good for health.

 

So how do we laymen reconcile these?

 

Some background to my question:

 

Wiktionary: phenol:

  • 1. A caustic, poisonous, white crystalline compound, C6H5OH, derived

    from benzene and used in resins, plastics, and pharmaceuticals and in

    dilute form as a disinfectant and antiseptic; once called carbolic

    acid.

  • 2. Any of a class of aromatic organic compounds having at least one

    hydroxyl group attached directly to the benzene ring.

  • Synonyms:

    (caustic compound derived from benzene): carbolic acid

Wikipedia: Catechin:

Catechin is a flavan-3-ol, a type of natural phenol and

antioxidant. It is a plant secondary metabolite. It belongs to the

group of flavan-3-ols (or simply flavanols), part of the chemical

family of flavonoids.

 

Interesting trivia:

... catechin chemical family derives from catechu, which is the tannic juice or boiled extract of Mimosa catechu (Acacia catechu L.f)

 

catechu:

Probably a corruption of the Malay kachu. A gummy extract of any of several species of Acacieae, produced by boiling the wood of the tree in water and evaporating the resulting liquid.

Edited by Greg Scott

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Cloud wrote:

 

I often do a second brew of my tea (in the first brew about 5 min as brew time). If I interpret correctly the table 7 after 300 s remains only 18.4% of catechins ?!

 

Yes - you are interpreting correctly. After 5 minutes, there isn't much of the healthy catechins left to extract from those tea leaves.

 

Greg wrote:

 

I'm wondering if the noxiousness of phenols [in tea, coffee, and many other healthy foods, like fruits and vegetables] is helpful according to the idea of hormesis... 

 

Yes, it is called xenohormesis and it is one of the leading theories as to why the mildly toxic compounds in plant foods appear to be healthy for us. See this post on the topic Xenohormesis: Whatever doesn't kill plants makes us stronger.

 

It is certainly nice to know mechanisms, but nutrition and metabolism are damn complicated. Sometimes the best we can do is look at the controlled trials to see whether the net effects of a food is positive or negative for health/longevity, or at least for markers/correlates of those outcomes.

 

Speaking of which, here is yet another new coffee study [1] suggesting benefits - this time by reducing DNA breakages. They had subjects in a lab drink a cup of coffee every two hours, and took blood samples which they analyzed for DNA breakages. They found that coffee rapidly reduced the number of broken DNA strands, and the effect increased through the 4th cup (the end of their trial). Since pretty clearly broken strands of DNA are bad news, this seems to be further evidence for the health benefits of coffee, this time immediate benefits from its consumption.

 

Of course one might question how the various benefits of coffee compare relative to the benefits of other healthy plant-based foods. Perhaps coffee appears so healthy in study after study because it is by far the biggest source of antioxidants in the standard American diet, as this graph sadly attests:

 

606.03BZ+-+Coffe+America+Number+One+Sour

 

But since unadulterated coffee (and tea) are zero calorie foods, we're in a position for once of not having to make a tradeoff between foods.

 

--Dean

 

-----------

[1] Mol Nutr Food Res. 2015 Dec 3. doi: 10.1002/mnfr.201500668. [Epub ahead of print]

Coffee consumption rapidly reduces background DNA strand breaks in healthy
humans: Results of a short term repeated uptake intervention study.

Bakuradze T(1), Lang R(2), Hofmann T(2), Schipp D(3), Galan J(4), Eisenbrand
G(1), Richling E(1).

Author information:
(1)Department of Chemistry, Division of Food Chemistry and Toxicology, Molecular
Nutrition, University of Kaiserslautern, Kaiserslautern, Germany. (2)Chair of
Food Chemistry and Molecular Sensory Science, Technische Universität München,
Freising, Germany. (3)Rosenthal-Bielatal, Germany. (4)Gruenstadt, Germany.

SCOPE: Intervention studies provide evidence that long-term coffee consumption
correlates with reduced DNA background damage in healthy volunteers. We here
report on short-term kinetics of this effect, showing a rapid onset after normal
coffee intake.
METHODS AND RESULTS: In a short-term human intervention study, we determined the
effects of coffee intake on DNA integrity during 8 hours. Healthy male subjects
ingested coffee in 200 ml aliquots every second hour up to a total volume of 800
ml. Blood samples were taken at baseline, immediately before the first coffee
intake and subsequently every two hours, prior to the respective coffee intake.
DNA integrity was assayed by the comet assay. The results show a significant
(p<0.05) reduction of background DNA strand breaks already 2 h after the first
coffee intake. Continued coffee intake was associated with further decrements in
background DNA damage within the 8h intervention (p<0.01 and p<0.001,
respectively). Mean tail intensities (TI%) decreased from 0.33 TI% (baseline, 0
h) to 0.22 TI% (within 8 h coffee consumption).
CONCLUSION: Repeated coffee consumption was associated with reduced background
DNA strand breakage, clearly measurable as early as two hours after first intake
resulting in a cumulative overall reduction by about one third of the baseline
value. This article is protected by copyright. All rights reserved.

This article is protected by copyright. All rights reserved.

PMID: 26632023

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Of course one might question how the various benefits of coffee compare relative to the benefits of other healthy plant-based foods. Perhaps coffee appears so healthy in study after study because it is by far the biggest source of antioxidants in the standard American diet, as this graph sadly attests:

 

606.03BZ+-+Coffe+America+Number+One+Sour

 

But since unadulterated coffee (and tea) are zero calorie foods, we're in a position for once of not having to make a tradeoff between foods.

 

--Dean

 

This chart is only showing the average American's dietary sources of antioxidants. Americans drink a lot more coffee than they consume tea and other wholesome foods, so of course it's going to be higher. A better comparison would be to assess antioxidant content standardized to a given amount of food, like 100g, which is exactly what these authors tried to do. It's also worth noting that comparing antioxidant capacities is very difficult as it's the methods of comparison ex vivo have major limitations.

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James wrote:

 

 

 

This chart is only showing the average American's dietary sources of antioxidants. Americans drink a lot more coffee than they consume tea and other wholesome foods, so of course it's going to be higher. A better comparison would be to assess antioxidant content standardized to a given amount of food, like 100g, 

 

Certainly if you want to know what people should eat/drink to maximize dietary antioxidant intake it would be better to compare foods by a standardized amount. 

 

What you are saying supports exactly the point I was trying to make by posting the graph. My point was that coffee may get all the headlines as being a uniquely healthly food because people eat so little of all the other (potentially as healthy or healthier) plant foods that are available relative to the amount of coffee they consume.

 

And I certainly agree with you that a crude measure like total antioxidant capacity is a poor measure of the potential health benefits of a food.

 

--Dean

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Has any coldbrew drinker out there had the same experience? Anyone willing to do an experiment to see if they have the same experience? I may try it again at home.

 

From my experience drinking Starbucks regular vs. cold brew I'd say I don't notice much difference, but I'm fairly sensitive to caffeine and my threshold for a relatively high buzz may be too low to make a good comparison. Caffeine Informer, using Starbucks website information, lists a 150 mg caffeine for 12 oz cold brew coffee and 180 mg caffeine for a 12 oz hot brewed coffee.

 

This is the best summary I could find, and falls in line with my understanding of the chemistry:

 

[....]

 

James, a very belated thanks for the extremely well put together research and analysis. I've been on the road and otherwise swamped for the last few weeks, and am finally catching up on my CR Society reading. I'm reminded again how much we need a wiki, to place analyses like yours (and many of Dean's and Michael's and others') up as part of a knowledge base.

 

I've continued with my 12-14 or so hour cold brew method -- 30 g light roast, 330 or so ml water (closer to 12 hours in the summer, closer to 14 in the winter in a badly heated space) -- I'm still digesting your post but it seems like the amount of caffeine I'm consuming from that is very unlikely to be enough to disturb my sleep (I'm a fast metabolizer), so I think I'll stick with it for now. Still trying to puzzle out the factors in coffee that may or may not have an influence on dementia risk. I may at some point start drinking more coffee, but partly as decaf.

 

Zeta

Edited by Zeta

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Al Pater posted another study [1] which (once again) has shown coffee to be beneficial, with the sweet spot in the range of 4-5 cups (6oz each) per day, which resulted in quite a sizeable 20% reduction in all-cause mortality among 90K US adults followed for about 10 years. One thing I find most interesting about studies (like this one)  that find coffee has health promoting effects, is that, unlike other associations between particular foods/beverages and improved health, coffee drinking is not generally associated with other healthy diet and lifestyle practices, which might confound the results. For example, people who eat a lot of blueberries are likely to be health-conscious and of higher socioeconomic status (since blueberries are relatively expensive). So studies that show blueberries are health promoting and help to preserve cognitive abilities may be questioned because of the other lifestyle factors blueberry-eaters engage in, and which may be difficult to control for in the statistical analysis.

 

In contrast, coffee drinkers aren't more likely to engage in other health-promoting practices, or be of higher socioeconomic status than non-coffee-drinkers. In fact, the opposite may be the case - those who are most health conscious may (mistakenly, IMO) think coffee is unhealthy, for whatever outdated reason - e.g. many whole plant food vegans (particularly raw foodists) believe coffee to be bad for you. This "no or even inverse association" between coffee consumption and other healthy diet/lifestyle practices is born out by the demographic data in this study, captured in this table from the full text (courtesy of sci-hub.io):

 

uPGst0e.png

 

As you can see, heavy coffee drinkers (in the columns towards the right), are more likely to:

  • Be men
  • Not have graduated from college
  • Smoke
  • Drink lots of alcohol
  • Report eating more calories
  • Report eating fewer vegetables and especially less fruit
  • Report eating more red meat and more saturated fat.

So rather than following a healthy lifestyle, the big coffee drinkers abuse their bodies more on average compared with non-drinkers.

 

But nonetheless, once these confounders were statistically accounted for (as best they could), the researchers found coffee (caffeinated and decaf alike) to be quite protective and health promoting, with:

 

Inverse associations were observed for deaths from heart disease, chronic respiratory diseases, diabetes, pneumonia and influenza, and intentional self-harm, but not cancer.
 
So drink up! (coffee that is).
 
--Dean
 

--------

[1] Association of Coffee Consumption With Overall and Cause-Specific Mortality in a Large US Prospective Cohort Study.

Loftfield E, Freedman ND, Graubard BI, Guertin KA, Black A, Huang WY, Shebl FM, Mayne ST, Sinha R.
Am J Epidemiol. 2015 Dec 15;182(12):1010-22. doi: 10.1093/aje/kwv146. Epub 2015 Nov 27.
PMID: 26614599
http://aje.oxfordjournals.org.sci-hub.io/content/182/12/1010.short

Abstract

Concerns about high caffeine intake and coffee as a vehicle for added fat and sugar have raised questions about the net impact of coffee on health. Although inverse associations have been observed for overall mortality, data for cause-specific mortality are sparse. Additionally, few studies have considered exclusively decaffeinated coffee intake or use of coffee additives.

Coffee intake was assessed at baseline by self-report in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. Hazard ratios were estimated using Cox proportional hazards models.

Among 90,317 US adults without cancer at study baseline (1998-2001) or history of cardiovascular disease at study enrollment (1993-2001), 8,718 deaths occurred during 805,644 person-years of follow-up from 1998 through 2009. Following adjustment for smoking and other potential confounders, coffee drinkers, as compared with nondrinkers, had lower hazard ratios for overall mortality (<1 cup/day: hazard ratio (HR) = 0.99 (95% confidence interval (CI): 0.92, 1.07); 1 cup/day: HR = 0.94 (95% CI: 0.87, 1.02); 2-3 cups/day: HR = 0.82 (95% CI: 0.77, 0.88); 4-5 cups/day: HR = 0.79 (95% CI: 0.72, 0.86); =/>6 cups/day: HR = 0.84 (95% CI: 0.75, 0.95)). Similar findings were observed for decaffeinated coffee and coffee additives. Inverse associations were observed for deaths from heart disease, chronic respiratory diseases, diabetes, pneumonia and influenza, and intentional self-harm, but not cancer.

Coffee may reduce mortality risk by favorably affecting inflammation, lung function, insulin sensitivity, and depression.

KEYWORDS:

additives; caffeine; cause-specific mortality; coffee; mortality

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Dean, thanks for the summary and analysis.

 

I think the key question for many of us would be: is coffee beneficial for someone on CR? We'd have to figure out more about the mechanisms whereby coffee exerts its beneficial effects, to see whether they're already occurring in someone on CR.

 

Of course, I'm not really on CR right now, so I'm going to up my coffee intake -- but I'm going to do so by adding decaf, to avoid sleep problems (knowing full well that some of the benefits of coffee appear to come from the caffeine).

 

Zeta

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