Since caffeine provides an enormous number of black coffee’s benefits, let’s start there.

The Benefits of Caffeine

Wakefulness, Alertness and Happiness

The most common belief about coffee: its caffeine wakes you up and keeps you awake.

There’s no surprise there. Most of us understood the primary benefit of coffee even before we started drinking it – because we saw our parents rushing to the coffee maker every morning, as soon as they got up.

Once we started drinking it ourselves, there was no mistaking the effects of a cup of joe. Whether we were gulping it down first thing in the morning, or drinking it for a pick-me-up later in the day, we began to count on coffee for its ability to get us going and to deliver an energy boost.

Caffeine’s ability to keep us alert and energized shouldn’t be a surprise. After all, caffeine is a stimulant that excites the nerves in the brain. In turn, that stimulates the release of adrenaline, the fight-or-flight hormone – and the adrenaline rush increases heart rate, blood flow and energy production. It’s no wonder we’re more alert and energetic after drinking coffee.

But that’s far from the only reason that coffee wakes us up.

Caffeine has a very unique molecular property. It is able to mimic the form of an important biochemical messenger, adenosine. When it does so, it pushes adenosine aside – preventing receptors in the brain from receiving the messages adenosine has carried through the nervous system.

What types of messages does caffeine block?

First of all, adenosine carries messages telling the body that it’s getting tired. The body’s production of adenosine increases during the day, so the longer we stay awake, adenosine receptors normally receive more and more of those “get tired” messages. Eventually, the body responds to the messages, and we get sleepy.

However, those messages can’t get through to the adenosine receptors if caffeine is blocking the way. The “tired” messages aren’t delivered until the effects of caffeine begin to wear off.

In other words, caffeine doesn’t really wake us up. It simply prevents our body from being tired.

Here’s the second reason that adenosine matters in this equation. It also delivers messages to control the flow of hormones and other neurotransmitters. So in most cases, adenosine receptors make sure that the brain isn’t overwhelmed by serotonin and dopamine (the “feel-good” hormones), dopamine – and adrenaline.

When caffeine is blocking the receptors, though, there’s no way for the brain to regulate coffee’s adrenaline rush or the other “happy” feelings it produces. So, in a strange way, caffeine’s behavior ensures that its stimulant effect is experienced to maximum effect.

If you’ve often thought that drinking coffee puts you in a better mood, that’s not just an illusion. It really does have that effect.

Brain Function

Black coffee’s ability to keep us awake and energized is partially responsible for its ability to clear the annoying “brain fog” we experience when we’re tired.

But there’s much more to the story.

Coffee has been shown to have a positive effect on cognitive function, memory performance, attention span and motor function. Studies with younger coffee drinkers found that their performance was more likely to improve when they might have otherwise been distracted. By contrast, caffeine helped older participants focus on complex tasks that required long periods of attention. In both cases, caffeine helps the brain function better.

Related studies have shown that caffeine is able to improve reaction time, by increasing the speed at which the brain processes information.

Some of that effect is credited to caffeine. But other ingredients in coffee seem to play a role as well; research has shown that drinking decaffeinated coffee also leads to improved memory span, alertness and attention, although not at the same levels that caffeinated coffee produces. Chlorogenic acids, one of the major classes of polyphenols in coffee, are believed to be responsible for some of that improved cognitive performance. 

Neurodegenerative Diseases

Here are two other health benefits of black coffee related to cognitive function.

The caffeine in black coffee has been shown to significantly reduce coffee drinkers’ risk of developing Alzheimer’s disease, the world’s most common neurodegenerative disease and the #1 cause of dementia. Research shows that drinking 3-5 cups of coffee per day in middle age corresponds with as much as a 65% lower risk of Alzheimer’s later in life.

Coffee drinking also appears to correspond with a greatly reduced risk of Parkinson’s disease, the second most-common neurodegenerative condition. Various studies have shown the lower risk ranges from 32-60%.

Heart Health

It’s been established that drinking coffee does not carry any cardiovascular risk, at least when total daily caffeine consumption is below 600mg – which is more than six cups of coffee every day.

However, there are indications that drinking black coffee can actually boost heart health. Caffeine generally acts as a vasodilator, meaning it widens blood vessels. That creates improved circulation and blood flow, important to good cardiovascular health.

Another factor in heart health is blood pressure. It’s normal for coffee drinkers to experience a brief increase in their blood pressure, as caffeine induces the release of feel-good and fight-or-flight hormones. But there’s some evidence that long-term, heavy caffeine consumption may lead to lower blood pressure in coffee drinkers.

It’s also been demonstrated that regular coffee drinking lowers the risk of heart failure. Apparently, that risk drops by as much as 12% per cup of coffee consumed per day. Other studies indicate that drinking coffee may lower stroke risk as well.

Even though it’s known that coffee doesn’t cause heart disease, the American Heart Association says it’s not yet ready to recommend that people drink more coffee in order to improve their heart health. The evidence, though, certainly leans in that direction.

Weight Loss

Black coffee is obviously a better choice than soda when you’re on a diet.

But there’s research showing that coffee is actually helpful for weight loss and fat burning.

Studies have found that caffeine can boost fat burning by nearly 30% in those with a healthy weight, and by 10% in those who are obese. The stimulant also helps people burn more calories because it speeds up the metabolism, and causes increased heat production in the body.

Simply drinking a cup of black coffee isn’t going to solve a dieter’s problem with obesity. However, a large meta-analysis of the data shows that caffeine appears to help coffee drinkers achieve reductions in weight, body fat and BMI (body mass index).

Endurance

When you think about workouts and beverages, you usually think about water or Gatorade. Perhaps you should add black coffee to the list.

Research has found that consuming caffeine right before exercising appears to significantly boost energy levels and improve endurance during a workout. The data isn’t quite as clear on how caffeine affects athletic performance, but one study reported that it seemed to be one of the reasons for improved athletic performance by participants.

Of course, if you think about the extra adrenaline release caused by caffeine ingestion, a boost of energy and better performance shouldn’t be surprising at all.

Headaches

If you’ve ever looked at a bottle of over-the-counter migraine pills, you probably saw that caffeine was one of the ingredients. There’s a good reason why; caffeine can help ease the pain of headaches and migraines.

You might remember that caffeine is a vasodilator in most parts of the body. In the brain, it has the opposite effect; it works as a vasoconstrictor, causing blood vessels to contract. Here’s why that’s important: there are sensitive nerves very close to the brain’s blood vessels, and headache pain is often caused when the two come in contact. When caffeine narrows the vessels they’re no longer pressing against those nerves, and headache pain may be eased considerably.

When considering coffee’s health benefits, it’s not always possible to separate the effects of caffeine and those of the other substances in coffee. That’s why some of the following benefits are primarily related to caffeine, some are primarily related to the “other substances,” and some can be credited to both. And the reasons for a few of the benefits aren’t well-understood at all.

We’ll start with the disease that’s most concerning to a high percentage of Americans.

Lower Risk of Cancer

Many news stories have focused on coffee’s protective effects against several types of cancer. Coffee drinking appears to reduce the risk of developing liver cancer by 40%. Data indicates there may be a significantly lower risk of prostate cancer in those who drink at least 2-3 cups of coffee each day. And those who drink at least 4-5 cups of coffee daily apparently have a lower risk of colorectal cancer.

What hasn’t received as much attention is a meta-analysis of the correlation between coffee consumption and other types of cancer. It found that coffee drinkers also had lower risks of oral, pharynx and colon cancer, endometrial cancer, and melanoma. Coffee intake was only associated with increases in one type of cancer, lung cancer, and some believe that may be related to higher rates of smoking among coffee drinkers.

Type 2 Diabetes

Coffee drinkers have been shown to have a lower risk of type 2 diabetes. The reason isn’t completely known, but it appears that every cup of black coffee reduces the risk by about 7%. The mechanism seems to involve the development of higher insulin sensitivity, meaning that coffee drinkers are better able to process glucose.

There have been many studies on the extent to which coffee helps lower diabetes risk, but the conclusions vary widely (between 25-50%) depending on the level of coffee consumption. It’s not clear whether caffeine content is directly related to protection against type 2 diabetes, but it has been found that decaf coffee does provide at least some protection.

However, coffee isn’t necessarily good for those who already have diabetes, because caffeine can have unpredictable effects on blood sugar levels. For that reason, diabetics are often advised to stick to 1-2 cups per day, or switch to decaf.

Liver Protection

The liver performs an enormous number of life-sustaining functions, from turning fat cells into energy, to cleaning toxins from the blood. Liver diseases like hepatitis and fatty liver disease are serious, and they often turn into cirrhosis (scarring of the liver) which can be life-threatening. Research shows, however, that coffee lowers the amount of dangerous liver enzymes in the blood; drinking at least four cups of coffee per day may reduce the risk of developing cirrhosis by as much as 80%.

Antioxidant Protection

Nutritionists recommend that we consume foods high in antioxidants like green vegetables, berries and beans. Those compounds help prevent the oxidative stress that can damage the body and cause a number of illnesses and diseases, including cancer. 

Coffee beans are very high in antioxidants like polyphenols and quinines, and most are retained in brewed coffee. In fact, coffee is the number one source of antioxidants for most people who eat a traditional diet.

Nutrition

The leafy green vegetables we just mentioned are certainly a better source of nutrients than coffee – but a cup of coffee does have nutritional value. It contains decent amounts of vitamin B2, vitamin B3 and vitamin B5, as well as minerals like magnesium, manganese, calcium and potassium.

One other note: coffee, particularly black coffee, is a diuretic. That means it causes you to urinate frequently – flushing bacteria and toxins from the system. Coffee with additives like milk and sugar, though, slows down that process.

Longer Life

All of black coffee’s health benefits, to state the obvious, can help you live longer. But research has quantified this most important of benefits. Female coffee drinkers have a 26% lower risk of death than those who don’t drink coffee; male coffee drinkers have a 20% lower risk.

Not really. At least, there are no serious side effects for people who don’t overdo the caffeine.

You’re probably familiar with the jitters and lack of sleep that are caused by drinking too much coffee. A few people who go over the line can also suffer panic attacks or heart palpitations. But the Mayo Clinic says 400 milligrams per day, or about 4-5 cups, is safe for just about everyone. (Pregnant or breast-feeding women should cut that amount in half.)

There are only two other concerns. High amounts of caffeine can be a problem for those on some anticoagulants, asthma medications, stimulants and anti-depressants; speak with your doctor if this is an issue for you. And unfiltered black coffee may occasionally cause increased cholesterol levels. If your cholesterol is already high, you might want to avoid boiling your coffee cowboy-style.