Evidence Review: Health Benefits of Coffee

10 min read

Do you drink coffee? Think you’re addicted to it and are afraid of the possible consequences? Let’s take a look what the latest scientific findings have to say about the effects of coffee on our health.

Article guide:

The main points are summarized at the end, as always.

Introduction

We all are familiar with coffee, most of us love it because it makes us more productive, it enables us to think more clearly, has a nice taste, we can work longer… the reasons are many. However, a lot of people dislike coffee because of old superstitions of possible negative effects which coffee supposedly has. This article will check the available evidence and list the positive and negative aspects of coffee consumption. As always, I will mostly focus on evidence from clinical trials, but I will also give the findings from observational studies as coffee has been studied quite extensively.

First, let’s take a look at the caffeine contents.

caffeinecontent

This gives you a good approximation of the amount of caffeine you consume with each beverage, it also gives you a good ballpark estimate on how much coffee should you drink to experience certain effects I will be stating. I’ve included some of the more popular soda drinks as well. Surprisingly, Mountain dew has more caffeine than Coca cola, which has been consistently mentioned for its caffeine contents.

Five important things to know

1. As you might know, the main psychoactive ingredient in coffee is caffeine. However, it has a number of minerals (manganese, magnesium, potassium, and niacin are the most notable) and vitamins (most notably vitamin b5 and b2).

2. Coffee is considered to be a psychoactive drug. By definition, a psychoactive drug crosses your blood-brain barrier and consequentially affects your central nervous system. Therefore, it can affect your brain function which includes changes in memory performance, alertness, and cognition in general. Ths information will become important in the latter part of this article, stay tuned.

Blood-brain barrier is a highly selective barrier which separates your circulating blood from the extracellular fluid in your central nervous system.

3. I would strongly like to emphasize that the mentioned effects are true for the general population without specific disorders. The mentioned effects will not be true for every single person on this planet, saying so is irresponsible. If you’re in the middle 95%, then it’s highly likely the information I’m about to present holds true for you. That’s just how statistics and nutritional science work. 

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4. With that said, a healthy liver will break down the caffeine contents of coffee by its enzymatic system. However, this isn’t necessarily true if you suffer from any liver dysfunctionality. [1]

5. Coffee tolerance is an extremely important thing to mention as well. Becoming tolerant to the effects of coffee can change the results of shorter randomized clinical trials. And studies have observed that we become tolerant to the effects of caffeine when it comes to blood pressure and our heart rate after only  4 days of drinking [2]. Moreover, the current evidence suggests that our reaction to drinking coffee is strongly affected by our genes. In some people, these effects and changes become much more pronounced than in others due to a certain genetic background [3]. This, together with the above curve, are both things that need to be addressed. Very few people seem to be addressing them and I find that sad.

With all that said, let’s start.

 

Effects of coffee on your cardiovascular system

Drinking coffee increases:

  • Flow-mediated dilation. [4, 5]

Flow-mediated dilation is a process, dependent from your inner blood vessel lining, which helps an artery to expand under increased workload.

This happens only when drinking regular coffee, decaf espresso doesn’t have this effect. The difference in flow-mediated dilation between the two is only around 2-3%, so the practical relevance for the general population is questionable [5, 6]. Moreover, in one of the studies, the decrease was very short-term and didn’t last longer than an hour.

One possible reason for these results lies in two particular substances. One is chlorogenic acid, and the other is a funky substance named hydroxyhydroquinone, which gets created during coffee bean roasting. It probably interferes with the protective effects of the before mentioned acid and cancels them out. [7]

  • Stiffness of your arteries. [8, 9]

However, there is an ongoing debate how long does this effect last.

  • Your blood pressure. [10]

However, this increase is very small and short-lasting. After you develop tolerance to coffee, or rather caffeine and the other compounds found in coffee, there seems to be no blood pressure increase for various people [11] nor people who already have high blood pressure. [10]

These results suggest that possible negative health effects of coffee on our health are very short-term and don’t seem to be visible in longer studies.

 

Effects of coffee on your lipids

Lipids are molecules that include fats, sterols (cholesterol), fat-soluble vitamins, triglycerides, and others.

There are two compounds, kahweol and cafestol, which are the main reason studies show increases in cholesterol levels. Namely, both of these substances have cholesterol-raising effects on our bodies, and both of them are found in unfiltered types of coffee such as Turkish coffee.

  • Unfiltered coffee intake does increase total cholesterol, LDL cholesterol, and triglycerides [13].

However, the increase in total cholesterol is a protective one – the balance between LDL cholesterol and HDL cholesterol improves, which is a good thing. Moreover, this review doesn’t mention the nature of the LDL cholesterol changes. This is very important because the number of your LDL particles is a better indicator of heart disease than LDL cholesterol levels themselves. [14]

The consensus about the health effects of coffee on lipids is not set in stone as of yet. On the one hand, there is a more favorable balance between LDL and HDL cholesterol, and a protective role of antioxidants found in coffee on LDL particles. On the other hand, there are the mentioned increases in cholesterol and triglycerides.

But if you’re worried about your cholesterol levels, when you stop drinking coffee they return to normal levels. [14]

Does coffee make me immortal?

I’d like to STRONGLY emphasize that the following evidence will be observational only. This means that people who are coffee drinkers are more likely to have this or that outcome. It DOESN’T mean that drinking coffee will instantly cause any of the mentioned effects. With that said, let’s see what does the evidence say about immortality and coffee.

People who are not used to drinking coffee seem to have an increased risk of stroke for a short duration after they drink it, very probably because they do not have a developed coffee tolerance, as this increased risk doesn’t seem to show itself if you’re drinking coffee regularly. [17]

Heart disease

  • Coffee doesn’t increase your risk for heart disease for healthy people [15] or people who had a heart attack in the past. [16]
  • Coffee doesn’t increase your risk for any type of heart disease. [10]
  • Women who drink moderate amounts of coffee even have a 18% lower relative risk of dying due to heart disease. [15]

But that’s not all of it. “What else is there?” Might you ask?

It seems you will have a 10-20% lower risk of stroke if you’re drinking coffee. [18, 19]

You will probably not get arrhythmia because of coffee. [20]

There is some available evidence where very high doses of caffeine were used to cause arrhythmia, however, these doses were very high and aren’t really achievable in a normal day of coffee consumption.

And there’s more.

  • It seems that a moderate amount of drinking coffee, around 3-4 cups, prevents heart failure. This effect gets diminished when you’re drinking more than that. [21]
  • Drinking coffee seems to be associated with a reduced risk for cirrhosis and liver cancer. [22]

This reduction in risk for cirrhosis and liver cancer is interesting. One would suspect that coffee would amplify inflammation because it binds to a particular set of receptors where other molecules would usually bind. But that’s obviously not the case. The observed reduced risk gives further weight to the notion that more compounds found in coffee, not just caffeine, have a very important effect on our body. The mechanism for these is not fully understood as of yet though.

Immortality?

Your chances of dying at any given time due to heart disease, stroke, injuries and accidents, diabetes, and infections are 10 to 16% lower if you drink coffee. These numbers slightly vary depending on the sex and amount of coffee you drink, however, they aren’t drastic [26]. This doesn’t mean you’ll become Dracula, it means that coffee drinkers are less likely to die because of the mentioned outcomes at any given time compared to people who don’t drink coffee.

Cancer

Drinking coffee seems to be associated with a lower risk for liver cancer, oral cavity-pharynx cancer, and endometrial cancer [27, 28, 29, 30], and an increased risk for lung and prostate cancer [31, 32]. For other types of cancer, the evidence so far is either mixed or neutral – suggesting coffee drinking doesn’t provide you with any benefit.

 

Coffee reduces your risk for diabetes

Drinking coffee seems to cut your chances of getting diabetes, with some staggering numbers. Different studies report different decreases [23, 24, 25]:

  • 25% (4 cups per day)
  • 33% (12 cups per day)
  • 35% (6 or 7 cups per day)

Drinking coffee also lowers the risk of dying for people with type two diabetes. [27]

I would really like to emphasize again that these are only connections. People who drank X amount of coffee had a Y% decrease in risk of getting diabetes. It could have been a number of other things that influenced the lifestyle of people who drink a lot of coffee.

 

Coffee and mental health

Parkinson’s disease

Drinking coffee seems to have a strong protective effect against Parkinson’s. People who drink coffee are between 33% to 40% less likely to have Parkinson’s at a later stage in life. [28, 29, 30]

Alzheimer’s disease

When it comes to Alzheimer’s, the preventive effects are somewhat disputed. Certain observational evidence says we’re less likely to have Alzheimer’s disease and suffer from cognitive decline in general if we drink coffee. Moreover, those who are mildly cognitively impaired seem to have a lower risk of becoming demented if they drink coffee. [31, 32]

Coffee and depression

Very recent observational evidence has found a link between drinking coffee and a decreased risk for depression and suicide. However, please understand that this is only a connection and not a proven “coffee will make you less depressed” sentence. [33, 34]

Coffee and anxiety

There is also some evidence that if you have a pre-existing anxiety disorder, or are just prone to anxiety because of stress, you might experience anxiety when drinking coffee in high doses. [36, 37]

 

Does coffee affect our metabolism?

You may or may not be already familiar with the majority of so-called fat burners that are being sold in the fitness industry include caffeine. And the reason for this is because caffeine supposedly boosts your metabolic rate through a process called thermogenesis. The amount by which it increases the metabolic rate seems to differ depending on our weight. In one study, obese women experienced a 5% boost in metabolic rate, while lean women experienced a 7,6% increase in their metabolic rate. [38]

What about coffee and osteoporosis?

Drinking high amounts of coffee is connected to bone loss, loss of bone density, and/or increased bone fractures in people who are more at risk for osteoporosis. However, there seems to be no sign there is the same connection in healthy people as far as newer evidence goes. [35, 36, 37]

 

Summary

  • Drinking coffee increases blood pressure until you develop coffee tolerance, it stiffens your arteries for a short amount of time and decreases your flow-mediated dilation for a short amount of time as well. These effects diminish if you become a regular coffee drinker.
  • Drinking coffee increases your HDL and LDL cholesterol, and triglycerides.
  • Drinking coffee has been connected to a lower risk of dying because of heart disease, stroke, diabetes, infection and accidents, and others.
  • Drinking coffee has been connected to a smaller risk of developing type two diabetes.
  • Drinking coffee does not cause arrhythmia.
  • There is less Alzheimer’s, Parkinson’s, depression, and dementia among people who drink coffee.
  • Coffee increases your body’s metabolism because of thermogenesis.
  • It’s possible that drinking coffee can cause bone loss, fractures, or bone density loss if you’re already at risk for osteoporosis.
  • Drinking coffee is connected to a lower risk for liver, endometrial, and oral cavity-pharynx cancer, and an increased risk for lung and prostate cancer.
  • Drinking coffee can cause anxiety if you have a pre-existing condition or are prone to anxiety.

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