Hearsay and rumor dominate the conversation about coffee and health. There’s a lot of mumbo-jumbo out there (like "weight loss coffee"), which makes it difficult to separate fact from fiction and discover what’s really going on in our bodies when we drink our liquid gold.

It’s also a problem that there’s no central source of information that coffee lovers can go to to learn about this stuff with actual hard data—but we’re going to change that.

This ultimate guide to coffee and health will cover a variety of topics related to health and lifestyle, using peer-reviewed research, to give you all the information you need to know to live an aware and healthy coffee-fueled life.

And, since new research is coming out all the time, we’ll update this article annually to keep it up to date.

We’ll cover things like…

• How caffeine damages your sleep quality (even if you don’t think it does)
• Why coffee shouldn’t be required to have a cancer warning
• How much is too much when you’re pregnant
• Whether Bulletproof Coffee beans are healthier than other beans

This guide is being written with research as the backbone, but please do not consider this the definitive source of health information. We are not doctors. If you have a serious concern or question about how coffee may impact your health, please consult your regular doctor.

Read: Starbucks VS Specialty Coffee: What's The Difference?

Get ready. We’re about to bust some bubbles and put down some rumors.

Start Here: A Summary Of Coffee’s Health Benefits

We’re about to dive deep into how coffee impacts your health, but let’s start off by summarizing the positive effects. Here’s what you have to look forward to throughout the rest of this guide.

Coffee’s not a miracle drink, nor is it all sunshine and rainbows, but the evidence is clear: coffee is overwhelmingly good for you. These health benefits are well-documented, generally undisputed, and are available to most people.

But don’t take our word for it. Let’s get into the actual research.

What Does The US Government Say About Coffee?

Every five years the federal government publishes a new version of the Dietary Guidelines for Americans. The 2015 release was the first ever to include guidelines for coffee—and it’s good news for coffee lovers.

“Strong and consistent evidence shows that consumption of coffee within the moderate range (3 to 5 cups/d or up to 400 mg/d caffeine) is not associated with increased risk of major chronic diseases, such as cardiovascular disease (CVD) and cancer and premature death in healthy adults.”

The report goes onto say that this level of moderate coffee consumption can be incorporated into a healthy diet. Consuming three to five cups of coffee per day (8-ounce cups) has been deemed non-threatening to your health by the United States government.

That’s the green light! But let’s go deeper and get more nuanced, starting with one of the big draws of coffee: caffeine.

How Does Caffeine Affect My Sleep?

The world loves caffeine, and 80% of America’s caffeine intake actually comes from coffee. But, like with anything, there is a point where you’ve had too much caffeine. Let’s look at how caffeine impacts you so that you can make informed, healthy decisions when it comes to how much coffee you drink.

How Your Body Absorbs And Processes Caffeine

For most people, it takes 45 minutes for your body to fully absorb the caffeine you put into it. From here, caffeine has a half-life of 4-6 hours, depending on your age, health, and genetics. This essentially means that, after 4-6 hours, your body as worked through ½ of the caffeine you gave it.

At this point, caffeine is impacting a variety of bodily systems, including making your dopamine (feel good) system more efficient. Let’s focus on one that’s related to sleep.

Adenosine is the compound that your body produces according to your circadian rhythm (your internal clock). When these compounds bond to receptors in your brain, your body knows to start winding down. Caffeine molecules, however, can also bond to the same receptors, which disables adenosine from being able to make you sleepy. You still need sleep, you just aren’t able to feel as tired.

The Best Times To Drink Caffeine

According to neuroscientist Steven L. Miller, there are only a couple hours of the day where caffeine is actually used at max-efficiency by your body. For most of the day, your body is naturally producing cortisol, a hormone that helps regulate your circadian rhythm and keeps your awake and alert.

When your cortisol levels are high, caffeine doesn’t really give you much of a boost (if you feel a boost, it’s just your body’s natural production of cortisol). However, you still build up a tolerance, even if you aren’t getting the full benefit.

The best time to drink caffeine for max energy efficiency is when you’re coming down from a cortisol high.

• 9:00 to 11:30 AM
• 1:00 to 5:00 PM

At these times, the caffeine gives your body a boost and doesn’t allow you to hit the natural low you would otherwise experience, especially right after lunch.

Read: The Best Time Of The Day To Consume Caffeine

The Worst Times To Drink Caffeine

Consuming caffeine at peak cortisol production won’t hurt you, but your body does still develop a tolerance to it, even though it’s not really boosting you. For this reason, Miller suggests avoiding coffee at these times:

• 8:00 to 9:00 AM
• 12:00 to 1:00 PM
• 5:30 to 6:30 PM

But that’s not all—late-night drinking of coffee can have some significant negative impacts. According to one study, drinking coffee a whole six hours before sleep can eliminate a full one hour of quality rest.

Think coffee doesn’t keep you up at night? You’re probably wrong.

In that same study, the researchers discovered that very few subjects self-reported a loss of sleep quality, yet every single subject could be documented losing quality sleep when overnight tests were run. As it turns out, we’re really bad at telling how well we’ve slept.

Common Complains About Caffeine

Though caffeine is largely associated with positive effects (as we’ll continue to explore further down), there are a few drawbacks. Most of them are avoidable with some proactivity, and we’ll show you how you can keep these negative side effects away.

Why Does Coffee Upset My Stomach?

For some, the joys of a delicious mug of coffee are followed by stomach discomfort. Most people automatically assume that this discomfort is caused by too much acid in the stomach from the coffee—which is actually only half right.

As has been known for a while, coffee does increase the acid in your stomach. However, it’s actually not the coffee’s acids that are responsible for the increase, but the caffeine. That’s right—caffeine causes your stomach to produce additional acids.

Chances are, you’re not actually extra-sensitive to acid (this is pretty rare). It’s also uncommon to have an extra sensitivity to caffeine (but it still happens).

Read: 3 Reasons Coffee Upsets Your Stomach (And What To Do About It)

However, it’s very common for an upset stomach to be caused by an empty stomach, which means the extra acids aren’t given a job to do. For most people, making sure you’re not drinking coffee on an empty or near-empty stomach will solve any upset stomach pains.

Can Coffee Give Me Acid Reflux Or Indigestion?

Many people (and doctors) assume that this increased rate of acid production is responsible for acid reflux, indigestion, stomach ulcers, and a variety of other gastrointestinal conditions. Sometimes the research suggests this, but other times the research cannot show any connection.

We’re not saying that coffee doesn’t affect these things, but the correlation between coffee consumption and some of these minor gastrointestinal issues is not clear or proven.

Can Caffeine Give Me Anxiety?

Unfortunately, for all the positive mental effects of caffeine, there is a negative—and it’s not insignificant: increased anxiety.

Any of these sound familiar to you?

• Nervousness
• Irritability
• Muscle Twitching
• Insomnia
• Palpitations

Most coffee lovers find that they become less irritable after a mug of coffee, but that’s not true for everyone. For some, high consumption of coffee can produce short-term symptoms similar to anxiety neurosis.

Full-time baristas, among many other professionals, commonly experience this. They drink coffee as part of quality control on the job, don’t sleep very well that night, wake up early the next morning to work at the cafe, and then drink lots more coffee to make up for the loss of sleep.

If you find yourself in this pattern, you may be experiencing anxiety without realizing it. Try changing things up and pushing through with less coffee and see how things go.

Read: Why Gratitude Makes You Happy

Is Decaf Coffee Dangerous?

In the 1970’s, one of the chemicals used in the decaffeination process, trichloroethylene, was declared a “cancer alert” by the National Cancer Institute. Yikes! This gave decaf coffee a bad name that’s continued on to this day. However, modern decaffeination methods aren’t nearly so alarming.

The FDA regulates Ethyl Acetate, one of the modern chemicals used to decaffeinate coffee. In high concentrations it can be dangerous for humans, so the regulation is that…

“(c) In coffee as a residue from its use as a solvent in the extraction of caffeine from green coffee beans, at a level not to exceed 10 parts per million (0.001 percent) in decaffeinated roasted coffee and in decaffeinated soluble coffee extract (instant coffee).”

In 1998, the FDA concluded that the trace chemicals found in decaf coffee are so rare that they do not pose a threat to your health.

Decaf coffee processed using the CO2 and Swiss Water Methods don’t even use chemical solvents, so they’re no threat either. These two methods (especially Swiss Water) are preferred by the specialty coffee community for their ability to preserve the coffee’s natural flavors.

However, you must remember that decaf coffee isn’t 100% caffeine-free.  The FDA allows up to 3% of the caffeine to remain in the coffee to be called “decaf”, which usually means there’s 3-20mg of caffeine in each cup of decaf.

Read: Skip The Coffee Aisle, Here's How To Find The World's Best Coffee

Does Coffee Dehydrate You?

For a very long time, coffee has been thought to dehydrate you. This idea can be traced back to a 1920’s book describing how coffee intake increases urination frequency.

Of course, now we know that coffee simply stimulates the digestive system and causes you to need to use the restroom more often. And naturally, if you drink more water, you urinate more.

New research is clear: coffee does not dehydrate you.

And, really, it’s not all surprising. Coffee is 98% water, after all.

Coffee And Cancer: What’s Going On?

Wow. This is where a lot of things go wrong and bad science is introduced. This realm of research is very complex, but we do know a few things for certain: coffee can be associated with reduced risk of some cancers.

However, that hasn’t stopped a California judge on March 29, 2018, from ruling that coffee sold in the state must come with a cancer warning.

Clearly, there’s a lot of debate and competing research in this area. Let’s dive in.

Should Coffee Come With A Cancer Warning?

On March 29th of this year, a California judge ruled that coffee sold in the state must come with a cancer warning label. This court case has been in debate since 2010, but it seems the warning will become standard.

Here’s why: acrylamide, a compound that may encourage cancer development, is produced during coffee roasting. But before you quit coffee cold turkey, let’s review this in context.

The coffee industry is astounded at this ruling and many companies will be filing appeals in the following weeks. Maybe the ruling won’t be put into law. Maybe it will be.

You can read more about Prop. 65 on the Specialty Coffee Association and National Coffee Association websites.

Read: How To Read Coffee Packaging Like A Pro

Does Coffee Really Reduce The Risk Of Cancer?

Let’s move onto a happier topic. As it turns out, coffee is actually associated with reduced risk of several cancer types. The World Health Organization, in a 2016 report, found that coffee is not a carcinogenic risk and not a cancer-causing beverage.

Let’s take a look at some of the cancer types that coffee can reduce the risk of.

Unfortunately, coffee has shown to possibly increase the risk of some cancers, namely ovarian and lower urinary tract. However these studies typically include disclaimers that more data needs to be collected in order to be confident in the results.

Overall, the relationship between coffee and cancer looks very good.

Coffee And Diabetes

According to a collection of over nine studies, moderate coffee consumption (more than two cups) is strongly associated with a decreased risk of type 2 diabetes. This is true for both regular and decaffeinated coffee. The reason? Well, we’re not really sure yet.

According to the Institute for Scientific Information On Coffee (ISIC)…

“Epidemiological studies suggest that drinking 3-4 cups of coffee per day is associated with an approximate 25% lower risk of developing type 2 diabetes, compared to consuming none or less than 2 cups per day. Research also suggests a dose response relationship.”

Though we don’t know why, it’s great news.

Read: How Manual Coffee Brewing Can Change Your Life

Coffee And Heart Health

Cardiovascular disease (CVD) covers an array of health issues that relate to your heart and circulation. Among these issues are heart attacks, strokes, hypertension, and coronary heart disease.

The American Heart Association, after consulting 36 studies, concluded that drinking 3-5 cups of coffee per day was strongly associated with a reduced risk of cardiovascular disease.

In a similar research roundup, the ISIC compiles data from dozens of studies and claims the following:

• 2 cups of coffee per day is associated with a 17% reduction in stroke risk
• Habitual coffee consumption is not associated with a higher risk for hypertension
• Filtered coffee does not increase serum cholesterol levels
• Non-filtered coffee can slightly increase LDL cholesterol and triglyceride concentrations
• 3+ cups per day is strongly associated with a 21% reduced risk of CVD mortality

The data is overwhelmingly positive, but with one drawback: if you have high cholesterol already, you’ll want to abstain from coffee brewers that don’t use paper filters, like french presses.

Can I Boost Workout Performance With Coffee?

Whether you’re a trained athlete or more of a normal person, good news, coffee can give you short-term performance boosts during physical activity.

The European Food Safety Authority concludes that…

“There is an association between caffeine consumption and an increase in endurance performance, endurance capacity and a reduction in the rated perceived effort or exertion during exercise.”

For many years, it was thought that you had to abstain from coffee for days or weeks before the ‘big event’ to get this performance boost, but this idea has been thoroughly disproven. The short-term performance boost is available even if you’re a regular coffee drinker.

Read: How Much Should You Pay For Coffee Beans?

Does Coffee Encourage Weight Loss?

Yes, actually, moderate coffee consumption can be associated with weight loss, but it’s more complicated than many people first assume.

Tests show that people who drink moderate or high levels of coffee tend to lose weight faster than people who drink none or little coffee—when a weight management system is in place. This means you can’t just drink more coffee and lose more weight. Your coffee consumption must act alongside other weight management strategies.

Here are the basics of how it works: the caffeine in coffee stimulates the nervous system and also causes your body to produce a small amount of adrenaline. These two factors both send signals to your body to break down stored fats and insert them into the blood. Coffee also increases your metabolism by 3-11%, depending on consumption level, which enables your body to process the fat in your blood as energy.

Read: This New Weight Loss Coffee Is A Hit On Social Media — And It’s A Big Scam

However, the positive weight loss effects are diminished in people who are obese and as age rises. If you already struggle with weight management, drinking coffee will not help much. But, once you have successfully lost some weight, its positive effects will kick in.

How Bad Are Cream And Sugar?

We won’t spend long here, because the science is so common and proven.

Black coffee has less than 5 calories per cup. For every teaspoon of sugar (4 grams) you dump in, you add 16 calories (and a whole slew of other health challenges). For every ounce of half-and-half, you get an additional 37 calories. Commercial creamers you’ll find at supermarkets often have 10+ grams of sugar per serving.

Here’s the thing: go easy on the cream and sugar. And if you really want to avoid the health challenges from tons of sugar, just drink black coffee.

Read: 5 Ways To Make Your Coffee More Eco-Friendly

Bulletproof Coffee: Sound Science Or Fading Fad?

If you’ve kept up much with popular health diets and claims of the last few years, you’ve certainly heard about Bulletproof Coffee. The man behind the company and movement, Dave Asprey, has been praised for his revolutionary approach to health and has also faced much criticism for it.

Is Bulletproof worth all the hype? Let’s find out.

How Bulletproof Coffee Is Claimed To Work

Making Bulletproof involves blending together a few ingredients that you probably wouldn’t have initially imaged as tasty. The result, though different, can actually be quite delicious. It’s almost like drinking a foamy latte.

• Black coffee
• Brain Octane oil
• Grass-fed, unsalted butter

This coffee, oil, and butter mixture is said to accomplish several things:

According to Asprey, not any coffee can help you achieve this though. The beans you use must be from high-elevation coffee farms that have extremely strict standards for mycotoxins and mold grown on the beans.

Let’s focus in on this coffee beans claim: Asprey concludes that most coffee is grown with high enough mycotoxin levels to cause health issues and keep your brain from performing as well as it should. What do researchers say?

Read: 3 Reasons Buying Cheap Coffee Is Bad For The World

Mycotoxins: Is My Coffee Killing Me?

Mycotoxins are present in many foods, especially non-processed foods. They’re a byproduct of fungi growth and are generally considered harmful to humans at high concentrations.

Asprey conducted an independent study that had half of his subjects drink Bulletproof’s own mycotoxin-free coffee and half drink regular coffee from a local coffee shop for six weeks. He concluded that the people who drank the mycotoxin-free coffee performed better in many aspects of life. Sadly, the study was never peer-reviewed or published in a journal, so it “statistical validity”—as academics would say—cannot be confirmed.

However, there have been plenty of other studies on mycotoxins—one’s that have been peer-reviewed and published.

Here’s the thing: mycotoxins are everywhere. They’re in peanuts, chocolate, grains, vegetables, tea, coffee, maybe in your building, and most likely in the air you breathe. Singling out coffee as a dangerous source of these toxins is unfair and, in the eyes of most coffee professionals, more of a marketing strategy than anything.

Sure, the natural coffee processing method does often result in more mold growth than coffee processed via the washed method. However, this creates awful flavors in the coffee—so awful that specialty coffee companies would not buy those beans. So, if you’re buying specialty-grade beans in the first place, you don’t need to avoid natural processed coffees.

Bottom Line: No, you don’t need to worry about mycotoxins in your coffee, especially if you’re buying specialty-grade beans.

What About The Other Health Claims?

Bulletproof does have some merit, but it seems many health professionals think that the majority of Asprey’s claims are unfounded and based on poor science. In fact, the two main studies that Asprey uses to make his claim about Bulletproof reducing inflammation and encouraging weight loss are based on rats and mice, but not humans.

One of the studies, "Switching from refined grains to whole grains causes zinc deficiency", is a report of a 1976 research project featuring a study group of just two people. A third study, "Diets high in grain fibre deplete vitamin D stores", is a 30 year-old study of only 13 people.

Among the claims that do make sense are that people should consume fewer carbs and sugars and also that a slight increase in fat consumption for most people could have positive gains. If you’re after a low-carb, high-fat diet, bulletproof could be a great move.

Since we’re primarily concerned about the claims made toward coffee and not necessarily the other elements, we’ll leave the conversation here. Though, we suggest doing more research yourself on these other health-related claims if you’re curious.

Is Organic Coffee Healthier Than Non-Organic?

For a farm to grow certified organic coffee, they must meet some pretty rigid standards:

• Coffee must not be grown using banned materials and methods, such as sewage sludge, ionizing radiation, and genetic engineering

• Production must be overseen by a USDA National Organic Program-authorized certifying agent

Read: Searching For Certified Organic Coffee - Is It Worth It?

That being said, some pesticides and fertilizers are still allowed. Most on the list are naturally occurring, but a handful are still made in a lab. So, in reality, sometimes organic coffee is grown with the help of chemicals—they’re just proven safe chemicals.

So is organic coffee more healthy than non-organic coffee?

Julia Craves is an ecologist at the University of Michigan Dearborn. In a column for the Specialty Coffee Association, she writes…

“Pesticide residue on foods is a major concern to consumers, but some recent work has determined that organic foods may not be any safer than conventional foods. This is true for coffee, where little or no chemical residue is likely to remain once the beans are removed from the fruit (the part exposed to pesticides), dried and hulled, roasted at very high temperatures, ground, then brewed in water.”

She does make the point, however, that organic farming can have significant benefits at the farm-level, especially for the environment and people who live downstream from coffee farms, where chemical runoff could be more severe.

So, while buying organic coffee can contribute to more sustainable and safe farming, it doesn’t really have an impact on your own personal health.

Coffee And Pregnancy: How Much Is Safe?

There are many competing ideas about pregnancy and caffeine intake, and there’s still a lot to be discovered. Pregnancy is, after all, one of the most complex processes the human body can go through, so it’s no surprise that the jury’s still out on this one overall. However, we are pretty certain about a few things.

Here’s the bottom line: 1-2 cups of coffee per day while pregnant appears to be perfectly safe. However, keep in mind that, even light caffeine consumption, newborns can experience withdraw-like symptoms during their first week outside the womb, so abstaining altogether is still something to consider.

Read: Why You Need To Be Drinking Coffee Black (And How To Start)

4 Additional Minor Health Benefits

Let’s spend a few moments talking about some benefits from coffee that are worth mentioning, but maybe don’t yet warrant a larger section.

Coffee can be connected to a variety of other health benefits or concerns, but we’ve touched on the most commonly discussed ones here. We’d be happy to hear your questions, concerns, or objections to the information discussed in this ultimate guide. If you want to make a comment, feel free to shoot us an email.

Coffee is fascinating, complex, and overwhelmingly healthy to drink. We’re thrilled to be providers of this amazing beverage to coffee lovers all over the country.

If you’d like to experience the lifestyle riches and health benefits of rich, freshly roasted specialty coffee yourself, including…

• Improved mood and alertness
• Reduced risk of many cancer types
• Reduced risk of type 2 diabetes
• Reduced risk of heart disease
• And more productive workouts