Coffee and Artery Function

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The Role of Caffeine in Artery Function

There are dietary guidelines for food, but what about for beverages? A Beverage Guidance Panel was “assembled to provide guidance on the relative health and nutritional benefits and risks of various beverage categories.” They ranked them from one to six, and water was ranked number one.

Soda ranked last at number six. Whole milk was grouped with beer, with a recommendation for zero ounces a day, in part out of concern for links between milk and prostate cancer, as well as aggressive ovarian cancer. Number two on the list, though, after water, was tea and coffee, preferably without creamer or sweetener.

Even without creamer, though, lots of unfiltered coffee can raise cholesterol, but the oily cholesterol-raising compounds are trapped by the paper filter in brewed coffee, so filtered coffee is probably better.

But about ten years ago, a study was published on the effects of coffee on endothelial function, the function of our arteries. I profile this study in my video Coffee and Artery Function, showing that within 30 minutes of drinking a cup of coffee there was a significant drop in the ability of our arteries to dilate, whereas decaf did not seem to have a significant effect. This was the first study to demonstrate an acute unfavorable effect on arterial function of caffeinated coffee, but one cup of decaf didn’t seem to affect performance. And two cups of decaf appeared to have a beneficial effect. So maybe it’s a “battle between caffeine and antioxidants.” Something in caffeinated coffee appears to be hurting arterial function, whereas something in decaf appears to be helping.

It’s similar to red wine. “De-alcoholized” (nonalcoholic) red wine significantly improves arterial function, as there are grape components trying to help, but the presence of alcohol counteracts and erases the benefit.

Drinking really high antioxidant coffee, for example by preparing it Greek style (where you actually drink the grounds), coffee drinkers may actually be at an advantage

It might not be the caffeine in caffeinated coffee that’s the harmful component, though. In a randomized, double-blind, placebo-controlled, cross-over study, researchers found that caffeine alone—about two and a half cups of coffee worth—significantly improved arterial function in both people with and without heart disease.

Coffee contains more than a thousand different compounds other than caffeine, many of which are also removed by the decaffeination process, so there must be something else in the coffee bean that’s causing the problem. In fact, caffeine may even enhance the repair of the fragile inner lining of our arteries by enhancing the migration of our endothelial progenitor cells, the stem cells that patch up potholes in our artery walls.

But how might we get the potential benefit of caffeine without the risky compounds in caffeinated coffee? Tea! Tea consumption enhances artery function, and there are substantial beneficial effects of both green tea and black tea. Instead of other components in tea leaves undermining caffeine’s potential benefits, they appear to boost the benefit in healthy individuals, as well as heart disease patients, reversing some of their arterial dysfunction, both immediately and long-term.

All the measurements in the studies I’ve talked about so far were done on the brachial artery, the main artery in the arm (just because it’s easier to get to). What we care about, though, is blood flow to the heart. And caffeine appears to impair blood flow to our heart muscle during exercise even in healthy folks, but especially in those with heart disease. Thankfully caffeine in tea form appears to have the opposite effect, significantly improving coronary blood flow, suggesting that tea consumption has a beneficial effect on coronary circulation, though the addition of milk may undermine the protective effects.

I’m fascinated by how complicated such a simple question can get! The take-home is that water is the healthiest beverage, followed by tea.

The effects of coffee on cancer risk are more salutary:

I also have videos on the effects on artery function of walnuts, dark chocolate, tea, eggs, salt, olive oil, vinegar, fatty meals, and plant-based diets in general.

Low Carb Diets and Coronary Blood Flow is one of the few other studies I’ve done that measured blood flow within the coronary arteries themselves. For more background on the brachial artery test, see my video The Power of NO.

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations—2013: Uprooting the Leading Causes of DeathMore Than an Apple a Day2014: From Table to Able: Combating Disabling Diseases with Food, 2015: Food as Medicine: Preventing and Treating the Most Dreaded Diseases with Diet, and my latest, 2016: How Not To Die: The Role of Diet in Preventing, Arresting, and Reversing Our Top 15 Killers.



Michael Greger M.D., FACLM

Michael Greger, M.D. FACLM, is a physician, New York Times bestselling author, and internationally recognized professional speaker on a number of important public health issues. Dr. Greger has lectured at the Conference on World Affairs, the National Institutes of Health, and the International Bird Flu Summit, testified before Congress, appeared on The Dr. Oz Show and The Colbert Report, and was invited as an expert witness in defense of Oprah Winfrey at the infamous "meat defamation" trial.

79 responses to “The Role of Caffeine in Artery Function

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  1. Excellent summary of a very complex subject. Thank you Dr G for all your clear and concise explanations. Coffee with it’s 1,000 different compounds must be a “Reductionist’s” dream playground :-)

    I’m a little puzzled by a couple of seemingly contradictory statements in the above article:

    1) “Even without creamer, though, lots of unfiltered coffee can raise
    cholesterol, but the oily cholesterol-raising compounds are trapped by
    the paper filter in brewed coffee, so filtered coffee is probably

    2) “Drinking really high antioxidant coffee, for example by preparing it Greek style (where you actually drink the grounds), coffee drinkers may actually be at an advantage.”

    I’m sure there’s a logical explanation and they’re really not contradictory, but I’m just not seeing it.

    I still drink filtered decaf coffee in the morning simply because I like the taste, but I switch to green tea in the afternoon/evening.

      1. i read an article a quite a few yrs ago, that came to 2 conclusions…oddly…..
        #1-…taken internally into the mouth…you can get up to 42 negatives
        #2-….taken internally…anally….up to 42 positives.
        i haven’t had coffee, itself, since 1985-ish
        [bottoms up]

    1. Coffee does not contain cholesterol but contains an oil called cafestol which may affect how the body produces cholesterol, and this depends on how you brew the coffee. If you let the water go through the coffee ground over and over several times like a French press then there is more oil but if you let the water go through once then you have less oil. I use an Aeropress and so the water only goes through the ground once but at high pressure so I don’t know how much oil goes into my coffee.. Funny, the coffee making technique is to get more oil into the coffee to increase its flavor, therefore increasing cholesterol. Nature never makes anything that tastes good and is at the same time healthy :)

        1. I would not worry too much about cholesterol in coffee because the amount is tiny. It’s good to know that it exists, but the coffee oil is what makes coffee tastes good. Plus the benefits from drinking coffee (up to 6 cups per day) outweigh the risks.

        2. K Cups are the bane of healthy eco-system and are major contributors to landfills. I have quit using them and plastic water bottles.

    2. From what I read, decaf and non decaf coffee have the same amount of antioxidant. So perhaps decaf is better because it has less oil. (but it does not taste as good :))

      1. Decaf has less, and lacks caffeine; tea has higher antioxidant levels than coffee.
        So that bottom line seems to remain– first water, then white tea with lemon or green tea.

    3. I have a BPH problem like most my age 82 and have been on meds to help. But still have night time urination waking me too many time. When it comes to diuretics, are those decafe coffee less than caffenated coffee? And same for tea?

        1. Thanks Jimmy, I have started drinking decafe coffee and Iced tea that sometimes has some caffeine. Don’t always know with all tea when you go to restaurants. Wish there was something to eat or drink to reduce urination.

    1. One trick I use with tea is to use Dr. Greger’s idea of hibiscus tea mixed with green or black tea. It really cuts the bitterness, and then I like it and I don’t have to add sugar.

    1. Final line in the link:
      “The Panel recommends that the consumption of beverages with no or few calories should take precedence over the consumption of beverages with more calories.”
      It must be the similarity of calorie count.

        1. …or maybe, since fruit juices have most of the calories of fruit (usually white grapes or apples) they were made from, but many fewer nutrients [tied up with the icky fiber], they’re not stupid at all.

          1. Well thats exactly my point. Just because something has the same caloric content and the same micronutrients quantities doesnt mean they will impact the body the same way. I remember a vídeo from Dr G showing people drinking lots of grape (if I remember right) juice without gainning weight. I have my doubts the same would happen drinking lots and lots of whole fat milk. And im just talking about the weight gainning.. i bet the inflammatory response would be much much different too for example.

            1. I don’t think weight gain was the panel’s chief concern, but ranking drink categories by contribution to overall health. Water is first (see Dr Greger’s daily dozen), then a calorie-free class of mostly healthy drinks, then relatively empty-calorie drinks, juices or milk.

              1. Exactly so I get back to my original thought. To classify this drinks only considering calories count you do it alone at home in 5 mins

                1. And then you miss the special benefits of water, the antioxidant benefits of plain tea and coffee (virtually noncaloric), and the greatly reduced value, apart from calories, of either fruit juices or milk.
                  No, they weren’t stupid.

                  1. I regret using the word stupid above. However I cant see how fruit juice can be at the same class as Whole milk if you consider other aspects than caloric content. But its just my perspective and our conversation is becoming circular..

  2. Is it really the caffeine in black tea that improves coronary blood flow or something else? Couldn’t see from the free abstract that this was tested.

      1. Thanks. I find the statements:

        “And caffeine appears to impair blood flow to our heart muscle during exercise even in healthy folks, but especially in those with heart disease. Thankfully caffeine in tea form appears to have the opposite effect, significantly improving coronary blood flow, …”

        hard to reconcile. The question I had was what specifically explains the differential effect? it would seem to have to be other components in tea, not caffeine in tea per se, which has the positive effect. In other words, I was wondering whether drinking decafe tea would have the same effect on blood flow.

        1. I cannot find any info on the Internet showing that caffeine in tea is better than caffeine in coffee. But tea contains only 1/3 the amount of caffeine in coffee. Decaf coffee still has some caffeine but much less than regular coffee.

          If you have a heart problem then you need to cut down on both coffee (regular or decaf) or tea. But if you are healthy then you should drink up to 6 cups of coffee per day because coffee is loaded with antioxidant.

          1. There is “info on the internet” linked in this very article. The caffeine is not “better”, it’s just that tea is a better vehicle for it since it doesnt have the negative effects that coffee does. Your second statement is in direct contradiction to this article. You should at least address this if you’re going to comment on it.

  3. Just learned that our common weed purslane is one of the most nutritious foods of the world, and includes much more omega 3s than flax. So I have been adding sprigs of purslane to salads and sandwiches and find it very tasty and crunchy, Why pay a lot for flax when omega 3s are right outside our doors? Is this a good idea? No pesticides in my yard.

    1. Marjorie: When I look up purslane, it looks to me like purslane has almost no fat: Where did you learn that purslane has more omega 3s than flax? Do you think I’m missing something?
      I’ll also note that Dr. Greger recommends flaxseeds for lots of reasons, but not necessarily because of their omega 3 content. So, for example, to replace flaxseed with purslane, you might ask yourself how much lignans the purslane has.
      To expand the point: I think the data is unclear on whether the typical body of a typical whole plant food eater can convert enough of the ALA in plant foods like flaxseed into the DHA/EPA that our brains need. To be safe/on the cautious side, Dr. Greger recommends that we at least consider taking algae-based omega 3s, which have the pre-formed DHA and EPA already in it.
      And yet, Dr. Greger still highly recommends that we consume about 1 tablespoon of ground flaxseed a day. But Dr. Greger is recommending the flaxseeds for other reasons than the omega 3s. For example, the high content of lignans in flaxseed are thought to have some great cancer fighting properties. There are other potential health benefits of eating flaxseeds. Here is the summary page for flaxseed on NutritionFacts:
      The point is: if purslane really has omega 3s, I’m guessing it would contain the ALA like flaxseed. In that case, it is unclear whether the omega 3s in purslane would be as much help as would be ideal. And so, if you wanted to replace flaxseed with purslane and still get the same benefits, purslane would need to have the other properties that make flaxseed so beneficial.
      That doesn’t meant that purslane can’t be a part of a very healthy diet. I don’t know either way. I’m just trying to give you a framework for answering your question. What do you think?

        1. WFPBRunner: I guess so! That site I linked to in my post above gets it’s data from the USDA database, which is usually pretty good. Here was my mistake: I saw a tilda/~ for the fats and thought that meant purslane didn’t have any or had only trivial amounts. I just reviewed the fine print on that page and found out that a tilde means that the data is missing or unknown, obviously not the same thing as zero.
          So, you found it. Thanks for those links! But now I have a question. The second link you provided was behind a paywall I think. The first link, I could only see the abstract. The abstract says that purslane is “rich in omega 3”. But going back to the original question, I’m wondering how that compares to flaxseed. According to the NutritionData.Self site, a tablespoon of flaxseed has 1597 mg omega 3s. The NutritionData.Self site says at the top of the purslane page that purslane has 5% fat, which isn’t much. Do you know how much omega 3 a tablespoon of purslane would have so we can compare it to flaxseed?
          Either way, purslane sounds pretty darn healthful. I’m interesting in trying it! I found one page on NutritionFacts on the topic: Very interesting.

            1. WFPBRunner: So, if I understand the study correctly, purslane has 26.6 mg omega 3 for 100 grams of purslane. According to NutrtionData.Self, flaxseed has over 22,000 mg omega 3 for 100 grams of flaxseed. So, it’s not really comparable. I would say that the omega 3 I purslane is “good” relatively. Purslane may be a good source of omega 3 compared to say other greens. But not in comparison to a powerhouse like flaxseed. Am I missing something or is that a correct analysis do you think?
              Note: I’m not trying to put purslane down. That green sounds awesome in general. I’m just trying to see if we can get an answer to the original question. How do you see it?

              1. I see from USDA data that 100 grams of flax have 534 Calories and the same for purslane, 20 Calories. Purslane has .36g total fat; if all was a-linolenic acid, a flax-calorie equivalent would have only 9.6 grams to flax 22.8; but among green plants, it’s excellent…in moderation.
                The oxalate is like spinach, and very little purslane satisfies you vitamin K need (not in USDA data)

        1. Vege-tater: Thanks for the article! I like the story at the beginning. I think the author has the amount of omega 3 wrong (see conversation with WFPBRunner). But the rest of the article seems really helpful. The discussion after the article is also good.
          Maybe I need to start growing another weed to annoy my neighbors. ;-)

    2. Marjorie I am pretty sure you are right. And I thought I got the information from here but of course I can’t find it. I add it to my smoothies when it is in season. You have me scouring the WWW. I’ll get a link for you.

    3. Love it too! We didn’t have any growing around here but found some growing in, of all places a crack in the pavement of a parking lot, and brought it home to reseed and spread! It’s a challenge to learn the different options here in FL after living in CT all my life, but so happy to have purslane again! Foraging is great fun, gets you out in nature, and best of all free food that’s more nutritious than anything on the store shelves!

  4. The following studies suggest the addition of milk to tea does not affect the subsequent bio-availability of flavanoids.

    The following suggests the bond between milk proteins and green tea is
    covalent (transitory). It may be the initial bond between tea flavanoids and milk proteins may be subsequently
    dismantled in the human digestive system?

    I am particularly interested in the chemistry of cocoa/milk (hot chocolate), if anyone can assist.

    1. Thanks for the references. They are interesting but I would not put too much weight on those studies.

      The first reference only looked at two fllavonols. The second reference discusses a scientist from Glasgow and saying “his hunch is that the milk does not stop the bioactive compounds (catechins) from being absorbed.” The third looked at green tea and milk. As far as I know, nobody drinks green tea with milk although drinking black tea with milk is very common. In any case, my limited understanding of that abstract suggests that it showed an adverse effect from milk?

      These all seem a fairly weak basis for assuming that it’s OK to drink tea with cow’s milk. Especially given that other studies suggest cow’s milk does degrade certain beneficial effects of tea eg

      1. Thanks Tom,
        There is no question tea flavonoids bind to milk proteins (not milk fats as
        proposed in the last reference you provided).

        I was attempting to convey that this binding may well break down in the
        human gut. If true, the initial binding is of no consequence in terms of
        flavanoid bioavailability.

        Neither of your references contradicts this possibility. One murine study
        suggests this binding actually enhances bioavailability:

        ‘The important new CSIRO study examined the effect of providing tea with
        10% milk, (compared to just 10% milk or just water) as the sole drinking fluid
        on UVA+B induced skin cancer in mice. The key finding was a significant
        reduction in the development of skin cancers in mice drinking tea with milk.

        “These findings are significant because initially it was thought milk may
        bind to the flavonoids, and impact on the antioxidant properties and potential
        health benefits of tea. The most recent findings would suggest that the
        protective role of the flavonoids is enhanced in the presence of milk,” said Dr
        Ian Record of CSIRO Division of Human Nutrition.

        In part, this effect coincides with the other references already provided.
        There may need to be more studies on this before we can have any certainty – one
        way or another.

        1. Thanks. You may be correct but I remain sceptical. However, I fully agree that more studies would be helpful.

          The different effects of tea and tea with milk on endothelial function seem to indicate that something is going on and, on balance, it is probably not beneficial ……
          “The most striking finding of our study is that addition of milk to black tea completely prevents the biological activity of tea in terms of improvement of endothelial function. Our results thus provide a possible explanation for the lack of beneficial effects of tea on the risk of heart disease in the UK, where milk is usually added to tea.18”

          I would also suggest that you look at any reports by CSIRO with a cautious eye. The primary purpose of CSIRO is “Assisting Australian industry”

          The cattle and dairy industries are hugely important in Australia abioth economically and especially politically. I am Australian and offhand I can’t recall the CSIRO ever publishing nay research which would in any way suggest that meat and dairy consumption might have downsides. Besides, that media story contains very little information and what there is, is confusing eg
          “The important new CSIRO study examined the effect of providing tea with 10% milk, (compared to just 10% milk or just water) as the sole drinking fluid on UVA+B induced skin cancer in mice. The key finding was a significant reduction in the development of skin cancers in mice drinking tea with milk.”

          I just think that all of this is very slender thread indeed to hang a claim on that drinking tea with milk is as healthy as, or more healthy than, drinking tea plain. The bulk of the evidence suggests otherwise.

        2. Oh, re your remarks about milk fat and flavonols……

          “The results from antioxidant activity assays (FRAP and ORAC),which were used to calculate the recovery of catechins, also suggest that absorbance to the MFGM reduced the antioxidant activity of catechins. This is consistent with the findings of Langley-Evans (2000a) and Ye et al. (2013) who reported a decrease in the antioxidant activity of tea catechins in the presence of full fat milk, whereas this decrease was less when catechin was added to skimmed milk. DerMarderosian and Beutler (2010) also speculated that the antioxidant capacity of tea catechins may be affected by the fat content of milk although there might not be a significant effect on catechin bioavailability. This statement supports the conclusions of Serafini et al. (2009) who reported that the total antioxidant activity of blueberry antioxidants was significantly decreased by the addition of milk, and the greatest degree of activity loss was seen when full-fat milk was added. These authors also reported some precipitation of blueberry antioxidants caused by milk components. In the present study, the MFGMs were washed,and association with caseins and whey proteins was minimised.”

          Catechins are flavonols (and flavonols are flavonoids) so I do not understand why you do not accept that milk fat does not bind flavonoids. Do you have any evidence to support this position?

          1. Thanks (fellow Australian) Tom for your most informative response.

            No evidence for or against the proposition, although most of the studies I have read refer to milk proteins.
            this recently discovered website – the best I have found in a decade of somewhat
            intermittent browsing. In particular, its attempt to deconstruct the often
            contradictory and perplexing big-picture.

            Tom, I take your point on the CSIRO.
            Nonetheless, they are not universally admired for skewing their research in
            favour of traditional agriculture:

            “It seems tofu-munching climate change extremists and animal libbers
            have taken over the CSIRO, wasting taxpayer funds to publish books designed to
            wipe out our agriculture industries with the ultimate goal of forcing farmers
            off the land,” Mr Vogels said.


            In regards the effect of milk-proteins on cocoa-polyphenols, I may have
            partially answered my own query:

            From a nutritional point of view, these data indicate that the β-Lg
            covalent modification by polyphenol alone do not support the hypothesis
            of a decrease in the bioavailability of polyphenols themselves (Scalbert &
            Williamson, 2000). This might also explain the maintenance of the
            antioxidant properties of cocoa polyphenols in cocoa-based beverages.

            This suggested that milk proteins sequester cocoa polyphenols limiting
            their adsorption in the gastrointestinal tract (Serafini et al., 2003). However,
            data in

            the literature are still conflicting, as later studies have found no
            reduction in the bioavailability of epicatechin when cocoa was consumed with
            milk (Schroeter, Holt, Orozco, Schmitz, & Keen,2003).


            Further, if milk proteins do not decrease the bioavailability of
            cocoa-polyphenols, the same could well apply to tea-polyphenols.

            As an aside. Notwithstanding the added sugar (which is an obvious problem)
            those wishing to place chocolate flavoured milk in the same category as cola for
            the purpose of additional taxation or regulation are (imho) doing us a great
            disservice. Especially children. This assumes the prepared drink is made
            principally from genuine cocoa, especially non-alkalised cocoa – as distinct
            from cocoa flavour.

            My gut feeling (not always a good guide) is that milk does not substantially affect the
            bioavailability of tea or cocoa polyphenols, despite their prior binding with
            milk proteins.

            Incidentally, Dr Gregor’s comments on milk/protein consumption in the
            elderly are fascinating. The theory appears to be that it counterproductively
            stimulates growth hormones There is also an apparent increased
            risk of Parkinsons and prostate cancer. In the absence of further research,
            I dont question the theory at all. However, it is worth noting the ‘longevity’
            industry is very busy pumping HGH into the middle aged and elderly. I just
            wonder if they are effectively decreasing longevity, rather than extending it.

            1. Thanks Pete. Yes, I had forgotten that particular furore. But I suspect that that particular report had been authorised and perhaps commissioned by the then Minister who would have been a member of the Rudd government (which wasn’t that concerned about rock solid Liberal/National constituencies). Under the Act, CSIRO also has to undertake work directed by the Minister. Ticking off some backwoods Liberal MP was probably just a bonus.

              My beliefs on this issue were initiated by that German study I quoted previously which showed impaired endothelial function from drinking tea with milk. I’d also been previously aware that while European tea drinkers showed cardiovascular benefits from their habit, British tea drinkers didn’t. That was the smoking gun for me. Whether or not flavonoids are bound for a short or long period seems to pale into significance compared to the observed effect on the cardiovascular system of drinking tea with milk.

              Since both my parents died relatively young from cardiovascular disease, that was a wake-up call for me and tea drinking (and I drink a lot). Concentrating on a particular process such as polyphenol binding but ignoring clinical effects and endpoints can be misleading (many thousands of processes are involved the body’s absorption of foods some of which may counterbalance, suppress or magnify other processes). There was a study which showed increased risk for cardiovascular disease in the UK with tea consumption and increased stroke risk in Australia. Elsewhere, in countries where tea is not usually drunk with milk eg Europe, tea consumption appears protective.

              I assume that the same risk applies to cocoa (and there is some evidence that it does) so I just drink the cocoa bean powder – no milk, no sugar. However, you might find this article helpful

              I don’t know about the chocolate flavoured milk but I assume all brands are loaded with sugar They would also be very high in (saturated) fat. Further, I doubt whether they use expensive quality ingredients in these products.
              As for the cocoa content, it is minuscule. Consequently, I do not think it would on balance benefit people’s health and I am relaxed about proposals to tax junk foods of any kind. Look at the ingredients/nutritional information for Moove and consider whether this would benefit anybody’s diet.

              1. “‘… I’d also been previously aware that while European tea drinkers showed
                cardiovascular benefits from their habit, British tea drinkers didn’t.
                That was the smoking gun for me.”

                That’s it for me, too, though I wish it were otherwise.
                I’m drinking a cup of Ceylon with soy milk right now. The caffeine is still available and maybe the cardamom I added in it still has some active constituents.

                I find this discussion very interesting; thanks to you both.

            2. I don’t think they tout HGH for longevity, but for anti-aging – feeling and looking younger. It can help with recovery from injury. Some people are willing to trade life span for perceived quality; so long as people are informed I think they should be able to make that decision for themselves.

      2. Green Tea with milk is popular in my area – Southern California – in the iced form of Green tea Latte, Green tea Boba, and Green Tea Ice Cream.

  5. I would be interested in a test for coffee and tea that included some added dairy to see how much an ounce or so outweighed the benefits of both cafe and decaf coffee and tea. My only animal based food is about a cup of 1/2 &1/2 a week in my tea and decaf filtered coffee. My cholesterol is under 150, and my blood pressure is OK-ish, and its just too hard to give it up.

    1. If you gradually reduce the amt of dairy in your drink, eventually your drink will not taste good with the added half & half…. Just a thought if you care. This happened to me with salt.

      1. Black coffee… I remember those days. I used to like it. Now it seems to be too acidic for me. I know dairy is acidic too, but does have an initial effect of being easier on my stomach. BTW I drink very strong dark roast. It behaves differently than SAD coffee. Really I was just curious from an academic interest, not so much for my own health. I only drink about 3 or 4 cups a week, and am more of a tea drinker when it comes to volume. I use almond milk in my tea and like that very much.

  6. “Black tea increases coronary flow velocity reserve in healthy male subjects.
    Hirata K1, Shimada K, Watanabe H, Otsuka R, Tokai K, Yoshiyama M, Homma S, Yoshikawa J.”

    What about all the high aluminum content I read about in Black Tea…?

    1. The bioavailability of aluminium in tea is low and would not normally cause concern unless you have kidney problems. Dr G did a video on this a few years ago I think.

  7. 1 The evolution of caffeine from coffee is different than from tea or cacao

    “They found that what we love about coffee — the caffeine — is a genetic quirk, not related to the caffeine in chocolate or tea.

    Albert says researchers discovered that caffeine developed separately in
    the coffee, tea and chocolate because it is in different genes in
    different areas of plants’ genomes.”

    2 Your genes determine the effect of caffeine, which could override the studies cited

    “The researchers, part of the Coffee and Caffeine Genetics Consortium,
    conducted a genome-wide meta-analysis of more than 120,000 regular
    coffee drinkers of European and African American ancestry. They
    identified two variants that mapped to genes involved in caffeine
    metabolism, POR and ABCG2 (two others, AHR and CYP1A2 had been
    identified previously). Two variants were identified near genes BDNF and
    SLC6A4 that potentially influence the rewarding effects of caffeine.
    Two others — near GCKR and MLXIPL, genes involved in glucose and lipid
    metabolism — had not previously been linked to the metabolism or
    neurological effects of coffee.

    The findings suggest that people naturally modulate their coffee intake
    to experience the optimal effects exerted by caffeine and that the
    strongest genetic factors linked to increased coffee intake likely work
    by directly increasing caffeine metabolism.”

  8. Wish I could enjoy the benefits of caffeine.
    Unfortunately It seems I’m allergic and it causes tachycardia and slight arrhythmias when I consume it. Even in small doses. And this has been an issue since my mid teens ( I’m now 35). I do however consume decaf tea and coffee ! Love it ! Thanks for the info and arming me with some ammo to combat all my co-workers in the morning when they give me weird looks and disparaging comments for imbibing on the unleaded stuff. I always tell them they will have give me a little extra time to wake up in the morning given I’m not high on stimulants like they are! I’ll only share the decaf beverage info with them. Lol.
    Keep the information coming ! And thank you for all the time and effort given to inform. You rock doc.

  9. I loved the questions this article stirs up in my mind. I was particularly in agreement with the statement “I’m fascinated by how complicated such a simple question can get!”. Truer words were never spoken, the interaction of compounds in food is frankly a little mind-boggling and truly separating out one compound which will always cause the same reaction no matter what context it is in is a bit of a fool’s game it seems to me.

    One can certainly double blind test a compound under a given set of circumstances – however to understand its effect in all possible combinations of contributing factors becomes daunting if not impossible.

    With that said, I am in general agreement with the concept of water as the number one healthy beverage followed by tea, and then followed by coffee. Coffee may be one of those balancing acts where the benefits and risks need to be accounted for and compensated – in other words we may be able to drink it and still reap its benefits while combining it with other actions or practices which ameliorate the risk. Based on this article, one is well counseled to understand and manage those risks.

    Very stimulating article, thank you.

  10. I am a Seventh Day Adventist with a Holy Spirit orientation to diet. The blue zone studies that reveal longevity to ones life and living a happier, healthier and longer life is backed also in complete abstinence from all stimulants, including coffee and tea (not herbal non caffeine type but excludes also green tea)
    An Adventist community in California outlive the average American by a decade. read the quote and study direct
    God bless to all for the search for the abundant life In Christ

  11. As a retired physician who is passionate about preventive medicine I am also concerned about the adverse effects.of coffee and caffeine. Many folks are unaware of the adverse effects of caffeine. they do not know that the caffeine industry has taken a lesson from the tobacco industry that was found to have produced more than 40 million documents trying to nullify the adverse effects of tobacco. See Am J Public Health 2001 Sept. vol 91 p.1419 Lead author Muggli, ME. I have proof that the caffeine industry has done the same although probably not to the same degree. I have recommended your book to a number of folks but am concerned about the places in which there are favorable mention of coffee-cafffeine. I often write articles on preventive medicine topics for my local newspaper. Donald E.Casebolt,, MD

    1. You seem to be making a point to tie coffee and caffeeine together as if to passive-aggressively refute the points made in this article, that they are in fact not to be tied together. Yet you didn’t give any counter-arguments.

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