Mini Mikkipedia - Coffee, tea and cardiovascular health

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Hey everyone, Mikki here, you're listening to Mini Mikkipedia on a Monday. And today I want to chat about cardiovascular disease health and coffee and tea consumption. And this is on the back of a review article I was looking at that investigated the topic of the potential benefit or negative impact that drinking either coffee or tea could have on cardiovascular disease health. And I've got to say up front that

If coffee and tea were detrimental in themselves, then we would be in a sorry state. But to be fair, we sort of are in terms of cardiovascular disease. It is the leading cause of death in the world, and it has steadily increased, and I believe from about 12.1 million deaths in 1990 to 18.9 million deaths in 2019 per year.

And of course cardiovascular disease prevalence has almost doubled from 271 million in 1990 to 523 million in 2019. So it's a significant burden not just at the level of the public health system but right down into society and obviously to the individual and their immediate family around them. And we drink a lot of tea and we drink a lot of coffee. So

Both of these contain caffeine and it's naturally present in both the tea leaves and the coffee beans. Of the type of tea that we drink to begin with, 78% is black tea and 20% of it is green tea and 2% is oolong tea. So both black tea and green tea are produced from the same plant.

occur through the different preparation processes. So they're made from the same plant, but the flavonoid content, so the catechins that are the polyphenol found in tea is greater in green tea compared to black tea just due to the different manufacturing processes. And of course, with coffee, there are like 85 different species of coffee, but three

are only commercially cultivated, the arabica, the canaphora, and the liberica. Caffeine is the most extensively researched phytochemical in coffee, and the metabolites of caffeine when it is metabolized in the liver have also been investigated in terms of their health impact, so the theobromine, the theophylline, and the paracenthine.

In both tea and coffee, polyphenols and caffeine are the most significant substances in terms of biology and medicine. So let's explore then what the potential impact of these are on cardiovascular disease health. So let's have a look at some of these mechanisms of action that have been studied. So coffee has been known to affect vascular endothelial cells by increasing the synthesis of nitric oxide, which is a vasodilator, and that's a good thing.

Caffeine also acts on vascular smooth cells directly and indirectly. So obviously as I said, it promotes a generation of endothelial nitric oxide, which diffuses into those vascular smooth muscle cells and indirectly causes vasodilation. But once nitric oxide reaches the vascular smooth muscle cells, it stimulates an enzyme that catalyzes the conversion of guanosine triphosphate, GTP.

to cyclic guanosine monophosphate, C-GMP. And this triggers another downstream process that results in vasodilation. So caffeine affects both the endothelial cells and the smooth muscle cells, allowing for free blood flow. Despite this vasodilation, there are some studies to show that there is a mechanism whereby caffeine can result in some vasoconstriction. However, this mechanism hasn't actually been found

studies looking at actual human arteries or animal models. So it might well be a mechanism of action that doesn't result in any sort of meaningful outcome. So it's likely, it's thought that this is just a transient vasoconstrictor effect and the main impact of vasodilation is the most important aspect here. Something to note though, is that for people with conditions such as liver cirrhosis or congestive heart failure, caffeine may best be avoided because

It is a strong blocker of something called adenosine, which is a substance in the body that typically causes the kidneys to constrict. And by blocking adenosine, caffeine can help increase the release of something called renin. This is an enzyme produced by the kidneys that play a crucial role in regulating blood pressure. In addition, caffeine can increase the levels of another substance that precedes renin in this biochemical pathway. And this further leads to blood vessel constriction in the peripheral

vessels around the kidney. As I said, this is an effect most noted in situations where renin levels are already high such as in-liver cirrhosis or congestive heart failure. So it is suggested that patients with these conditions might be better off consuming little or no tea and coffee. Outside of that though, for people who are perfectly healthy, there's no detrimental impact in this space. The last mechanism of action is of course caffeine's effect on the adenosine receptors.

which I was just talking about there. So the primary mechanism of action of caffeine is non-selective inhibition of the adenosine receptor. So it blocks all four adenosine receptor subtypes in the body. And because caffeine is both fat and water soluble, it penetrates all the systems in the human body. In the central nervous system, caffeine inhibits the depressant effect of adenosine, thereby altering our sleep arousal cycle.

cognition, memory and learning. And we are all likely familiar with the alertness effect that you can get from caffeine. Caffeine does induce a reflex activation of the sympathetic system by inhibiting the adenosine receptors in circulation. And this can result actually in tachycardia and increased peripheral vascular resistance. Not everyone has this impact. And in fact, there is a heap of evidence to support the claim that non-habitual coffee consumers are more likely

experience this increase in peripheral vascular resistance compared to people who usually drink it. And in fact, if you are a habitual drinker, you're much more likely to be tolerant of the effects mediated by adenosine. When I'm talking about tachycardia, I'm really just talking about an increase in heart rate and the resistance in the periphery blood vessels is in fact, increasing blood pressure. But as I said, this is for people who don't habitually consume

caffeine so if you're like me quite tolerant you're not going to get this potential impact. So caffeine both through coffee and tea does stimulate the central nervous system and causes those sympathetic nerve terminals to produce more noradrenaline. It improves alertness and wakefulness, promotes attention and can boost productivity as you know. Because of its action in the sympathetic nervous system, caffeine is thought to have significant effects on blood pressure but

As I just mentioned earlier, there is a lot of conflicting information. So that acute effect of coffee really is only likely to occur in non-hibitual drinkers. And this is what researchers have found when they've studied this question. Caffeine consumption also has a positive influence on the incidence of Alzheimer's and cardiovascular health as a result of its impact on blood sugar and vasodilation. We've just talked about the mechanism. So what does the studies actually reveal about?

caffeine and its impact on health. So firstly of course is its sympathetic nervous system effects. It improves alertness and wakefulness. It promotes attention and boosts productivity. And it does have those peripheral effects that could impact on cardiovascular health. It is thought to have significant impacts on blood pressure. But as I just described, it is more likely to affect non-habitual drinkers than it is people who are habitual drinkers of caffeine.

And interestingly, coffee has also shown quite favourable changes in patients with insulin resistance. Consumption of more than five cups of coffee has been shown to increase adiponectin levels and decrease insulin resistance, which decreases the possibility of patients developing type 2 diabetes. So for those of you unfamiliar, adiponectin is a protein hormone that plays an essential role in regulating glucose levels and fatty acid breakdown in the body.

primarily produced by fat cells in the adipose tissue and has a number of functions related to metabolism and inflammation. Therefore, drinking coffee that increases adiponectin levels is of course very helpful. Caffeine consumption also has a positive influence on the incidence of Alzheimer's disease and cardiovascular health as a result of the effect on adiponectin. Coffee contains cholesterol increasing lipids known as di-terpenes and these include

and kaiwal, and the extraction in the coffee depends on the method by which it is brewed. Filter coffee has lower concentrations of the di-terpenes as the coffee is in contact with the hot, wet water for a short period of time, whereas boiled coffee is said to have a larger concentration of them because it has prolonged contact with hot water. A randomized trial conducted in young adults in 1989 revealed no significant change in

in LDL and total cholesterol values in subjects who consume filter coffee, but there was a significant increase in serum cholesterol levels in subjects who consumed the boiled coffee, so with more di-terpenes. A meta-analysis of randomized controlled trials in 2012 showed that people who drink more coffee have higher triglycerides, total cholesterol, and LDL cholesterol.

caffeine promotes LDL receptor expression and LDL cholesterol clearance. So the study of the impact of coffee and tea on lipid levels is pretty inconsistent. And for what it's worth I will also say that the study on cholesterol levels and cardiovascular disease also appear to be quite inconsistent. Anyway, we know the impact that obesity and excess body fat has on cardiovascular disease.

and tea and coffee have been demonstrated to have an anti-obesity impact due to their numerous influences on lipid metabolism and appetite suppression. Of course, this doesn't hold true if you're having your coffee with sugar, caramel and whipped cream, because obviously that is going to impact on the health benefits of drinking coffee. However, drinking one or more cups of black coffee daily has been linked to a decrease in the risk of heart failure.

hasn't extended to decaf coffee actually. There are definitely some questions around caffeine impact on causing arrhythmias because there is earlier studies performed on animals showing that there were increased arrhythmias due to the caffeine in coffee yet subsequent studies have failed to prove that this is a causative association and in fact coffee could even have an inverse relation to arrhythmias. So it's quite...

Clear that the research is mixed in this regard. Regular consumption of moderate amounts of coffee, 1-3 cups a day, is associated with a protective effect of ischemic stroke risk. In habitual consumption of large amounts, more than 6 cups of coffee has not been observed to exert a significant effect on stroke risk. Which is very good because I think sometimes I might drink 6 cups of coffee a day. This may well be due to the anti-inflammatory and insulin sensitizing effects.

of coffee. So people are traditionally recommended to limit their coffee, tea and caffeine use since it may increase various parameters that could be detrimental to physical health, such as, as I've mentioned in this little mini episode, blood pressure, total cholesterol and triglycerides. But large scale research has not found this to be the case and in fact there's a relationship between the practice of drinking coffee and decreased risk of cardiovascular

heart attacks and diabetes due to their anti-inflammatory, antioxidant and potential fat burning properties. Recent studies illustrate a non-dose response relationship between caffeine intake and cardiovascular disease risk. Caffeine in the form of coffee and tea, if consumed in moderation, appears to be harmless for young adults and has the potential to modify cardiovascular risk factors in the future in a favourable way. In conclusion then,

antioxidant properties and anti-inflammatory effects. And it directly activates the physiological systems in the body, which increase the production of nitric oxide through the nitric oxide synthase. It also acts as a vasodilator through other mechanisms that are involved in the actin-myosin cycle. Caffeine has a mild transitory vasoconstrictive effect as it increases intracellular calcium

So patients with congestive heart failure and non-habitual drinkers are more prone to experience an increased sort of blood pressure from this, but people who habitually drink it do not need to be worried about it. Moderate amounts of tea and coffee seem to be protective against heart failure. Arrhythmias like atrial fibrillation help prevent restenitis after coronary stent placement and also help prevent Alzheimer's disease.

Of course these effects are going to vary on an individual basis depending upon genetic polymorphisms which I did not go into, but also of course coexisting risk factors and co-morbidities. Whilst earlier studies showed that we had increases in triglycerides, total cholesterol and LDLC, newer research shows that these beverages can in fact be anti-obesity, have an appetite suppressing effect.

and may well increase fat burning, which doesn't necessarily result in fat loss, but it does make you a more metabolically healthy human. So overall then, coffee and tea does appear to have a cardio protective effect on certain populations, particularly healthy people, through their anti-obesity, appetite suppressant and fat burning effects. So if you are a habitual drinker and you don't get an increased anxiety from it, it doesn't

should continue to drink these as you wish, ensuring of course that you also hydrate through other mechanisms, i.e. such as water. There you go. These mini-micropedia for you on a Monday, all about coffee and tea. I don't know about you, but Monday seems to be a very good day for me to drink coffee. And also, interesting on the fat burning front, if I just tangent a little bit to my Anatomy of Fat Loss mini-course series that is being run.

Sunday 5th of May through to Wednesday 8th of May, for anyone who is looking for the most up-to-date evidence base on how to sustainably lose fat and keep it off. I'm gonna do a deep dive into all the mechanisms that you need to know about to help you with your fat loss goals. You can sign up either on my website,, head to my Instagram, there'll be information there, @mikkiwilliden.

You'll also find me on Twitter @mikkiwilliden, or head to my Facebook page, MikkiWillidenNutrition, and you'll find information there. All right, team, you have the best week. See you later.