Coffee and caffeine — How much do you have to drink?

Coffee contains hundreds of compounds that are bioactive.

It actually serves as a single largest source of antioxidants for many people all over the world. Studies also show that coffee drinkers have a lower risk of conditions such as type 2 diabetes, neurological disorders, and liver diseases.

however, you may wonder, how much coffee is safe to drink and whether there are any risks to excess intake. This article explains the amount of coffee you can drink safely.

How much caffeine does a cup of coffee contain?

The most commonly consumed psychoactive substance in the world is caffeine, an active ingredient in coffee.

The content of caffeine in coffee varies greatly from 50 to over 400 mg per cup.

A small home-brewed a cup of coffee could supply 50 mg, while a large Starbucks 16-ounce (475-ml) packs more than 300 mg.

As a general rule, you can assume that around 100 mg of caffeine is available in an average 8-ounce (240-ml) cup of coffee.

Several sources suggest that for most healthy adults, 400 mg of caffeine per day—the equivalent of 4 cups (945 ml) of coffee—is safe (3Trusted Source, 5Trusted Source).

Many people, however, drink much more without any problems. Keep in mind that there are many other sources of caffeine, including tea, soft drinks, chocolate, energy drinks, and certain medicines (6, 7 Trusted Source).

SUMMARY Your morning joe's caffeine content can range from 50 to more than 400 mg. Many sources recommend 400 mg of caffeine a day for healthy adults as the safe upper limit.

Short-term excess intake symptoms

If you drink too much coffee over a short period of time, you may experience mental and physical symptoms, including:

1. Restlessness

2. Anxiety

3. Dizziness

4. Stomach irritability

5. Insomnia

6. Quick heartbeat tremors

If you experience such symptoms after drinking coffee, you may be sensitive to caffeine and should consider cutting your intake or avoiding caffeine altogether.

While it is possible to die from an overdose of caffeine, from coffee alone this is nearly impossible. In a single day, you'd have to drink over 100 cups (23.7 liters).

However, after taking caffeine supplements, there are a few rare cases of people dying.

SUMMARY Too much caffeine may cause different symptoms, mostly associated with your brain and digestive system.

People tolerate varying amounts of caffeine in different ways affecting people. Many genes that affect the sensitivity of people to this stimulant have been discovered.

These genes affect the enzymes that break down the caffeine in your liver as well as caffeine-affected receptors in your brain.

Genetically determined are also the effects of caffeine on sleep.

Some people can drink coffee immediately and go to sleep, while others are kept awake all night long.

You can tolerate a lot of caffeine, or very little, depending on your genetic makeup. Most of the people are in the middle somewhere.

Also very important is your acquired tolerance. Those who daily drink coffee can tolerate far more than those who rarely drink it.

Realizing that medical conditions can affect caffeine sensitivity is also important.

You may tolerate less caffeine if you have anxiety, panic, heart arrhythmia, high blood pressure, diabetes, or other medical conditions.

Talk to your health care provider if you want to know more about your tolerance.

SUMMARY Caffeine sensitivity is highly variable and depends on your brain's caffeine genes and receptors.

Coffee and longevity While high intakes of caffeine cause adverse side effects, there are many health benefits associated with coffee. It was even associated with increased longevity.

In one study in 402,260 people aged 50–71, those drinking 4–5 cups of coffee per day had the lowest risk of death over the study period of 12–13 years. Two other reviews supported similar results. Research is mixed, though.

A recent study found that drinking 4 or more cups per day was associated with an increased — not decreased — the risk of death among people under 55 years of age (14 Trusted Source). Note that these and most other studies do not specify whether "cup" is a standard 8-ounce (240-ml) cup or just a generic vessel that can be used by people to drink coffee, regardless of volume.

However, there are generally not very large variations in volume between coffee cups of different sizes.

SUMMARY Although the evidence is not settled, several studies suggest that coffee drinkers live longer — with the optimum amount of coffee about 4–5 cups a day.

Coffee and disease risk Coffee was also associated with a reduced risk of different diseases, including type 2 diabetes. The more people who drink coffee, the lower the risk of type 2 diabetes. For each daily cup, one study found a 7% decrease (15Trusted Source). Cirrhosis of the liver. Drinking 4 or more cups of coffee daily results in the greatest reduction — up to 84% — in liver cirrhosis, a serious consequence of certain liver diseases (16Trusted Source, 17Trusted Source). Cancer of the liver.

For every 2 cups a day, your risk of liver cancer is reduced by 44% (18). The disease of Alzheimer. In one study, 3–5 cups per day were associated with an Alzheimer's disease risk (19Trusted Source) decreased by 65%. The disease of Parkinson. Coffee is associated with Parkinson's reduced risk, with the greatest reduction seen at 5 or more cups per day (20). Depression. Studies have shown that 4 or more cups of coffee per day are associated with a 20% lower risk of depression and a 53% lower suicide risk (21Trusted Source, 22Trusted Source).

So it seems optimal to aim for 4–5 cups of coffee per day. Since all of these studies have been observational in nature, they cannot prove that coffee has caused disease reduction—only that coffee drinkers are less likely to get these diseases.

These results, however, are worthy of consideration. In most cases, the same beneficial effects should have on decaf coffee. Parkinson's disease, which seems to be affected primarily by caffeine, is an exception.

SUMMARY Coffee consumption was associated with a reduced risk of many diseases, with the biggest effects being around 4–5 cups a day.

During pregnancy, caffeine can cross the placenta and reach the fetus in pregnant women. The fetus has problems with metabolizing caffeine, however. Some studies associate high intakes of caffeine during pregnancy with increased risk of miscarriage, death, premature delivery and lower birth weight (23Trusted Source, 24Trusted Source, 25Trusted Source, 26Trusted Source).

It is generally recommended that pregnant women limit their intake by about 1–2 cups (240—475 ml) of coffee to 100–200 mg of caffeine per day.

However, during pregnancy, many experts recommend avoiding coffee altogether. This is a clever choice if you want to be absolutely safe.

SUMMARY Concerns have been raised about the effect of caffeine on the developing fetus, so avoiding or minimizing coffee intake when you are pregnant is generally recommended.

Recommended intake Evidence suggests that the optimal amount maybe 4–5 cups of coffee per day. This amount is associated with the lowest risk of premature death and a lower risk of many common diseases, some of which affect hundreds of millions of people.

That doesn't mean you have to drink coffee, of course. It should definitely be avoided by people who are sensitive to caffeine, have certain medical conditions, or simply do not like this beverage.

What's more, you may want to reduce or eliminate your intake if you like coffee but find it tends to give you anxiety or sleep problems. In addition, by adding sugar or other unhealthy, high-calorie ingredients, you can easily negate the benefits of coffee. Still, to get the maximum benefits, it is possible to optimize your java.

SUMMARY Evidence suggests that the greatest health benefits are associated with 4–5 cups of coffee per day.

If you are sensitive to caffeine, however, you should aim for lower amounts or completely avoid coffee.

The Bottom line

There is very little evidence of harm for people who enjoy coffee — and plenty of evidence of benefits.

While it can be optimal for 4–5 cups per day, Many people can tolerate more without problems. If you like to drink a lot of coffee and have no side effects, there is no reason to stop drinking it.