What’s better in the morning than a fresh, hot and steamy good old cup of Joe? Well, for most Americans, it’s the first thing we do in the morning when we wake up. It wakes us up, it increases our metabolism and it gives us that little boost of energy we need to start the day off right. And at least for me, if I miss this part of my morning ritualistic, the rest of my day feels off. So, what is it about coffee that makes us love it so much? Do we love it enough to put it in front of our health?
The effects of coffee, in particularly its caffeine, on our overall health has always been a hot topic for researchers. First, we thought coffee was bad for your health, especially your heart health. Right? We were told to limit our caffeine consumption to only 1-2 cups per day because experts feared drinking too much caffeine would raise your risk of heart disease and stunt your growth. However, despite the warnings from doctors and researchers, coffee consumption remains high amongst the majority of Americans and around the world. According to the National Coffee Association, on average, Americans drink 3.1 cups of coffee a day and around 64% of Americans drink at least one cup a day.
But, recently, more and more studies have been coming out stating that coffee is actually good for you and may even help prevent against certain diseases like type II diabetes mellitus, Parkinson’s disease, and certain types of liver cancer. Most shockingly, some studies are showing that coffee consumption actually might improve your heart health. So, which one is it? Is coffee good or bad for you?
What is Coffee and how does it work?
The exact origins of coffee are not known, but we do know coffee has been around for awhile and there is evidence linking it all the way back to the 15th century. However, according to several myths and legends, coffee has been around for a lot longer. The most well known legend traces its heritage all the way back to the ancient coffee forests of the Ethiopian plateau. And it all begins with a goat. Yes, I said a goat.
The legend says that Kaldi, an Ethiopian goat herder, was the first to discover the altering effects of the coffee bean when he noticed his goats acting very frisky and jumpy after eating a certain type of shrub. They were more energetic than usual and to the point where they couldn’t sleep. Naturally, his curiosity led him to trying some of the shrub's berries for himself. Lucky for him, he was the first to experience the buzz. He told the abbot at his local monastery about his discovery of the energizing berries, and the buzz quickly spread east to the Arabian peninsula and coffee's future was secured as a global, staple of life.
Coffee contains many ingredients, and is well known for its caffeine, chlorogenic acid, and diterpenes. Caffeine is what gives coffee its kick. Its chemical name is trimethylxanthine (C8H10N4O2) and it can naturally be found in some plants, such as coffee beans and different types of teas. In its pure form, caffeine is a very bitter and white crystalline powder. It’s classified as an addictive stimulant drug that affects the brain by acting on the Central Nervous System, just like amphetamines, cocaine and heroin. However, caffeine is a much more milder stimulant compared to those drugs. Since it’s a stimulant, it can be considered medically useful in stimulating heart activity and acting as a mild diuretic by increasing urine production to help flush fluid and waste products out of your body.
Figure: Caffeine Chemical Structure
How does Caffeine Stimulate You and Wake You Up?
Caffeine acts on your brain chemistry. While you’re awake, the neurons in your brain are continuously firing away. Throughout the day your body needs a continuous supply of energy. In order to support this need, your body is always breaking down a high-energy molecule called ATP. While ATP is being broken down, it frees its chemical backbone, adenosine, as a byproduct,which is the key sleep-inducing molecule in your brain. The compound adenosine is being constantly monitored by your nervous system through binding to adenosine receptors in your brain. When adenosine comes in contact with these receptors, it activates a cascade of biochemical reactions causing adenosine levels to drop to a certain level, causing the neurons in your brain to fire more sluggishly. As a result, your body will signal to you to start relaxing and prepare you for sleep by slowing down your nerve cell activity and causing you to feel drowsy. It will also cause your blood vessels to dilate (blood vessels relax and open up, instead of constrict and stiffen up). This improves blood flow throughout your body, so you can better supply your organs with oxygen rich blood while you are sleeping.
When you ingest caffeine, it’s basically mimicking the effects of adenosine in your body. It’s able to do this because caffeine has a similar chemical molecular structure to that of adenosine , which is close enough to let caffeine wedge into the adenosine receptors, but NOT close enough to activate them. This tricks your body into thinking that it’s not yet time for sleep by blocking your body’s adenosine receptors and preventing adenosine from binding to its receptors. Your body’s cells can no longer properly identify adenosine because caffeine is taking up all the receptors that adenosine would normally bind to. That’s why caffeine can also be referred to as an adenosine receptor antagonist. It’s essentially hindering the process that is incharge of slowing down your neurons by blocking your adenosine receptors and causing your neurons to speed up, instead of slow down. Your pituitary gland senses this activity and automatically assumes you are in some type of emergency or stressful situation. In response, your body releases hormones that signal your adrenal gland to make epinephrine (better known as adrenaline), which is the "fight or flight" hormone and has several effects on your body:
- It increases your heart rate.
- It increases your blood pressure.
- It expands and opens up your airway passages (this is why individuals who suffer from severe asthma attacks are sometimes injected with epinephrine).
- It dilates your pupils.
- It causes the blood vessels in your brain to constrict by blocking adenosine receptors (this is why some medications that treat headaches, such as Anacin, contain caffeine because this constriction of blood vessels in the brain helps stop or at least improve vascular headaches).
- It redistributes blood flow to your muscles so they are ready for to take action by constricting the blood vessels near the surface of your skin as well as the vital organs of your digestive system, including your stomach.
- It increases your metabolism, so you can better maximize blood glucose levels to be used as energy, primarily by the brain.
- It causes your liver to release stored sugar into the bloodstream to be used for extra energy.
That’s why after drinking enough coffee, your hands start to feel cold, your muscles become tense, your heart begins to beat faster and you start to feel more excited. Caffeine also affects the neurotransmitter dopamine in your body, which activates certain pleasure centers in parts of your brain. Addictive drugs like cocaine, methamphetamine and heroin manipulate dopamine levels in your body by slowing the rate of dopamine reabsorption. Caffeine also increases dopamine using the same mechanism, but the effects are a lot weaker. And this is what makes caffeine so addicting.
In summary, adenosine is responsible for suppressing (inhibiting) your neurons, while caffeine prevents this inhibition of neuron firing by blocking adenosine receptors, allowing you to feel awake and alert. In the short term, caffeine is beneficial when you are running low on sleep and still need to remain focused and active. It gives you an extra boost when you need one by injecting adrenaline into your body’s system and it makes you feel good by manipulating levels of dopamine. But, what about in the long term?
So, Is Coffee Good or Bad for You?
According to the American Heart Association, and I’m sure most habitual coffee drinkers will happily agree, coffee consumption actually does offer some health benefits:
- It wakes you up and helps you get your day started off right.
- It gives you some extra energy and can even improve your mood.
- It sharpens your mental focus and helps your brain work better.
- It may help you lose weight by boosting your metabolic rate and suppressing your appetite.
- It improves your performance during exercise.
- Its antioxidant properties help protect your cells from oxidative damage that can cause cancer. This might explain why some studies have found coffee drinkers to have a lower risk of liver disease and liver cancer (Saab et al., 2014).
Coffee’s powerful metabolism boosting and antioxidant properties can help lower your overall risk of some diseases. Research shows that individuals who engage in regular coffee consumption have a lower risk for developing type 2 diabetes, Parkinson’s disease, and Alzheimer’s disease. In one study, higher consumption of coffee – caffeinated and/or decaffeinated– was associated with an overall lower risk of total mortality (death), including deaths attributed to heart disease, nervous system diseases (ex. Parkinson’s disease and Alzheimer’s disease) and even suicide (cite). More specifically, habitual coffee drinking is linked to a lower risk of coronary heart disease in women.
Research links excessive coffee consumption, specifically if you drink 5 or more cups a day, with a substantially lower risk of developing type 2 diabetes. Although the consumption of caffeine alone (i.e. energy drinks and caffeine pills) is associated with an increase in blood glucose levels and a decrease in insulin sensitivity, which both are associated with increased risk of type 2 diabetes. This might sound counterintuitive, but the important thing to take away is that there is something in coffee that protects against type 2 diabetes and that it’s not just caffeine alone that’s responsible for coffee's benefits (Van Dam, Pasman and Verhoef (2004).
Evidence from multiple studies have shown that coffee consumption may be associated with reduced risk of gallstone disease that’s strongly linked with an increased risk of gallbladder cancer. Experts believe the reduced risk is due to caffeine's ability to decrease gallstone formation. Its antioxidant effects helps protect the body’s cells against from oxidative damage, as well as reduce levels of inflammation (Larsson, Giovannucci and ??, 2017).
Is Caffeine Safe for Patients with AFib and other Arrhythmias?
For some people when they drink too much coffee that may start to feel heart palpitations. The Aleksandr Voskoboinik et al. study assessed the association between caffeine intake and its effects on atrial and ventricular arrhythmias, which revealed a consistent decrease in incidents of atrial fibrillation (AFib) for the individuals who increased caffeine consumption. And that caffeine, even at doses up to 500 mg daily (6 cups of coffee), does not seem to increase an individual’s likelihood of ventricular arrhythmia. Researches are concluding that naturally caffeinated beverages (sorry guys this doesn't hold truth for energy drinks) may have long term, protective antiarrhythmic properties. Thanks to caffeine's strong antioxidant properties and its antagonism effect on adenosine that I explained earlier. Many other population-based studies also show that individuals who regularly consume coffee and tea at moderate levels have an overall lower risk of developing heart rhythm problems (Voskoboinik, Kalman and Kistler, 2018).
Is Coffee Bad for You?
Well for all the health-conscious coffee lovers out there, the most important question to ask really isn’t, “Is it good for you?”. Instead, the more important question is, “How do you take it?”. Just one cup of black coffee packs quite the punch. It makes you feel awake and alert, comes with numerous health benefits and is only a few calories. So what’s the problem? Well, first off, did you notice how I said a cup of BLACK coffee in the previous sentence and didn’t mention those fancy lattes and frappuccinos we like to indulge in and post on our instagrams. The federal dietary guidelines says that 3-5 cups of coffee per day can be part of a healthy diet, but that’s only referring to plain black coffee. That’s because adding endless amounts of sugar and creamer to your coffee everyday, ends up negating some of the health benefits that coffee provides. Just one frappuccino can have up to 800 calories or more. These extra calories quickly add up, causing weight gain and as a result, it will adversely affect your cardiac health. Even if your dressed up cup of coffee doesn’t cause you to exceed your daily caloric needs (ex. you replace your breakfast with a latte so you are not consuming more calories than you need and don’t gain weight), you’re still negating some of the benefits simply because the negative health effects that come with consuming sugar, especially if you are drinking more than 1 cup of dressed up coffee everyday.
The federal dietary guidelines above suggest drinking up to a MAXIMUM of 5 cups of black coffee per day. That’s because when caffeine is consumed in excess it can be dangerous and have negative health consequences. I’m sure most of you have experienced drinking one cup too many and as a result, you started to feel jittery and maybe even feel your heart fluttering. When coffee starts to make you feel this way, you are most likely drinking too much caffeine and it should be a warning sign to start limiting your consumption. It’s important to note that some people can tolerate more caffeine than others depending on the amount of coffee they consume and their metabolism. This is because some people have a genetic predisposition that makes them slow metabolizers of caffeine, making them more sensitive to the effects of caffeine when broken down in the body and will experience more jitters, heart palpitations and/or insomnia. This genetic mutation is actually fairly common. Individuals with this genetic mutation should be more conscious about limiting their total caffeine consumption because some studies suggest that when they consume 2 or more cups of coffee a day, they are more at risk of developing heart disease.
The time of day you drink your coffee is also important to think about. You don’t want to consume caffeine too late or it will disrupt your sleep. And not getting enough sleep has its own negative effects on health, including one’s cardiac health and risk of heart disease. That’s why I do not condemn college kids drinking coffee all night to stay up and study. Research shows that students who lose hours of sleep and pull all nighters to study, actually perform worse compared to the students who studied less and got more sleep.
I think it’s also important to point out that the average 6-ounce cup of drip-brewed coffee (unfiltered) contains around 100 mg of caffeine, whereas an 8.4 oz energy drink such as Red Bull has 80 mg of caffeine and an 12-ounce cola soft drink only contains about 50 mg of caffeine. I often hear coffee consumers brag about how they choose the healthy caffeine option compared to people who get their caffeine from other sources like energy drinks and sodas. But, most of them probably aren’t aware that an energy drink has less caffeine than the average cup of Joe. Energy drinkers may argue that there is a double standard when it comes to caffeine options other than coffee or tea. However, energy drinks are usually much higher in sugar content compared to both unsweetened and sweetened coffee. Just one Monster Energy Drink contains 54 grams of sugar. To put that into perspective, researchers found that the regular coffee consumer on average adds 3 teaspoons of sugar a day to their coffee (3 teaspoons of sugar is equal to 14.3 grams and 41.3 Calories). Interestingly, tea drinkers on average only add 2 teaspoons of sugar (36.7 Calories) a day to their tea (Yates, 2017). Energy drinks are also an unnatural source of caffeine and made with many artificial preservatives, flavors, and dyes, whereas coffee is considered a natural because it’s found in nature.
Caffeine, like any other substance, can be addictive. If your adenosine receptors are always loaded with caffeine due to over consumption, your body will naturally respond by manufacturing more receptors. Now, even when caffeine is present, there are too many open adenosine receptors for caffeine to block all of them and adenosine is able to bind to some of the open receptors and still send signals to your brain to power down. That’s why regular coffee drinkers will eventually need to consume more and more caffeine to feel the same amount of alertness because the number of adenosine receptors that caffeine needs to block has increased. This is also why quitting coffee cold turkey can cause unpleasant withdrawal symptoms, including terrible migraines and depressed moods. If you want to start limiting your caffeine intake and avoid withdrawal, then it’s important to slowly cut back and taper off. After a few days without caffeine, the extra adenosine receptors that were produced in response to your overconsumption of caffeine will start to disappear. Your body will eventually adapt and re-adjust to feeling the same amount of alertness that you would have felt after your morning coffee routine without needing to consume excess amounts of caffeine.
Coffee and Cholesterol Levels
Recently there have been many mixed claims about coffee and cholesterol levels. After extensively reviewing all of the research, it’s clear that engaging in regular coffee consumption can increase your cholesterol levels, but it depends on how you brew it, how you take it and how much you drink it. Let’s examine this further.
Thus far, research hasn’t exactly linked coffee consumption alone with a direct association of increased rates of cardiovascular and heart disease. However, some studies have made the connection that some types of coffee can adversely affect your cholesterol and lipid levels. Coffee acting as a stimulant in the body is not the main reason for coffee's effect on cholesterol levels, rather it can be attributed to the special chemicals called diterpenes (also known as coffee oils), such as cafestol and kahweol. When consumed they tend to decrease important bile acids and neutral sterols in your body, which negatively affects your ability to properly metabolize and regulate cholesterol. In turn, this can lead to increased cholesterol levels. In particularly, the coffee oil, cafestol, is considered the most potent cholesterol-elevating type of compound in the human diet.
These coffee oils are naturally found in both caffeinated and decaffeinated coffee. In 2001, Klag and his colleagues linked drinking unfiltered coffee with an increase in LDL (“bad”) cholesterol levels, total cholesterol and triglycerides, whereas drinking filtered coffee didn’t lead to the same increase in cholesterol levels. This is because unfiltered coffee is brewed by continuously passing hot water through the coffee grounds for a prolonged period. Examples of common unfiltered brewing methods include using a French press (aka a cafetière or plunger pot), Turkish coffee, Greek coffee, espresso (and cappuccino since it’s made using espresso) and Scandinavian boil. Whereas filtered coffee is brewed using an American-style coffee pot with a filter and hot water is only passed through the coffee grounds once. During this brewing process, the majority of the coffee oils are left behind in the filter, no matter what type of roast is being used (i.e. caffeinated vs. decaffeinated, medium roast vs. dark roast). As a result, filtered coffee has substantially lower levels of cafestol and doesn’t have the same affect on your body’s ability to metabolize and regulate cholesterol. That’s why drinking filtered coffee isn’t directly linked to raising cholesterol levels. An important study revealed that drinking 5 cups of French pressed coffee a day on average is associated with a 6-8% increase in blood cholesterol levels, and drinking 10 cups of unfiltered coffee a day is associated with an average of a 20% increase in total cholesterol levels. A different study determined that out of all the different ways to enjoy coffee, Turkish-style simmered coffee and Scandinavian-style boiled coffee have the highest levels of diterpenes, instant coffee and drip-brewed coffee have “negligible” amounts, and espresso has intermediate amounts. It’s important to note that in these studies, levels of HDL (the “good” type of cholesterol) do not appear to be affected by drinking coffee, filtered or unfiltered.
The mechanism by which these coffee oils raise cholesterol levels is not yet completely understood. Experts believe that when these oils are digested, they are able to activate a protein called farnesoid X receptor (FXR) that is located in your intestine, which in turn activates a gene called fibroblast growth factor 15 (FGF15). Once this gene is activated, it can now negatively alter the effects of 3 different genes located in your liver, which are all involved in regulating cholesterol levels. Drinking unfiltered coffee with high amounts of cafestol and kahweol are more than likely to activate these genes and cause an increase in your cholesterol levels.
To make things even more confusing, I want to play the devil's advocate by pointing out that these same coffee oils that cause an increase in cholesterol levels also have important antioxidant properties and health benefits, such as preventing cancer and improving overall liver health, which are lost when they're filtered out. As you can see there are several pieces to the coffee story that’s trying to determine whether or not coffee’s positive health effects outweigh its negative effects. It’s more than just a battle of filtered vs unfiltered coffee. It’s also about how much coffee you drink, filtered or unfiltered. As well as, what else are you doing besides drinking coffee. You can’t be too quick to make coffee the main culprit of your increased cholesterol levels and overall risk of heart disease. Are you a smoker? Do you consume a diet high in cholesterol? Does your family have a history of high cholesterol? And so on.
Besides the effects on cholesterol levels, drinking coffee is also linked to increased levels of homocysteine (a naturally occurring substance that forms when the body breaks down protein). A higher concentration of plasma homocysteine is associated with an increased risk of CVD. Both unfiltered and filtered coffee raises homocysteine levels. But, drinking filtered coffee is associated with a greater increase in homocysteine. And compared to decaffeinated coffee, drinking caffeinated coffee is linked to a bigger increase in homocysteine. Researchers suggest that the caffeine in coffee has some responsible for this effect, but the chlorogenic acid that’s in coffee (which can get filtered out depending on the brewing method) also plays a role in increasing homocysteine levels (Verhoef, Petra et al., 2002). The good news is that the raise in homocysteine levels aren't permanent. By eliminating or at least limiting the amount of unfiltered coffee you consume will help homocysteine levels return back to normal. And increasing intake of or taking B vitamins, especially B-6 and folic acid, will help reduce and control homocysteine levels. Vitamin supplements, green leafy vegetables and citrus fruits are good sources of folate.
More research is needed in order to determine the exact effects of regular coffee consumption on cholesterol and lipid levels, as well as on long-term health and its role in preventing or causing diseases. So, if a patient asks me if they should or should not stop drinking coffee, I explain that it’s not just a simple yes or no answer. Instead, I work with the patient to "filter through" their medical and family history, current state of health and disease risk, everyday lifestyle behaviors and genetic makeup to make an individualized assessment of how much and what type of coffee the patient can drink without increasing their cholesterol levels and raising their risk of heart attack.
In the meantime, if you are trying to watch your cholesterol, you may want to try lowering your consumption of unfiltered coffee if you currently drink large amounts of it on a regular basis. It’s also a good idea to try and limit the amount of additives you add to your coffee, such as heavy cream, sugar and carmel. And since caffeine increases your body’s production of adrenaline, it’s best for the individuals who already have high blood pressure and/or heart disease to be more cautious about their coffee consumption and always consult their coffee habits with their doctor.