Transcript: Coffee & Artery Function
There are dietary guidelines for food; 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 1 to 6, and water ranked #1.
Soda ranked last at #6. 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 thanks to IGF-1. #2 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 levels, but the cholesterol-raising compounds are trapped by the paper filter in brewed coffee, so filtered coffee is probably better.
But about 10 years ago a study was published on the effects of coffee on endothelial function, and the function of our arteries. 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 for 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—maybe the antioxidants.
It’s like the story with red wine. De-alcoholized red wine significantly improves arterial function, so there are grape components trying to help, but the presence of alcohol counteracts and erases the benefit.
Drinking really high antioxidant coffee, by preparing it Greek style, for example, where you actually drink some of the grounds, may actually offer an advantage
That something in caffeinated coffee that appears to hurt, though, may not be the caffeine. In a randomized, double-blind, placebo-controlled, crossover study, researchers found that caffeine alone—about 2 1/2 cups of coffee worth—significantly improved arterial function in both people with and without heart disease.
See, 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 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? From tea. Tea consumption enhances artery function. Substantial beneficial effects for 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 in the long-term.
Now all the measurements in this and the other studies 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 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, although the addition of milk may undermine the protective effects.
To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by Katie Schloer.
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