Dietitian Explains the Benefits and Risks of Caffeine

Used as a naturally occurring stimulant for thousands of years, the world has recently begun taking a more critical look at caffeine.

Is caffeine bad for you, or is caffeine good for you?

Understanding what caffeine is, and its possible benefits and drawbacks, can be helpful information when people are deciding if caffeinated products are right for them.

What Is Caffeine?

Caffeine is the world’s most widely used drug, and 85% of people in the United States drink at least one caffeinated drink each day. (1)

It is a psychostimulant, which means that it can temporarily increase or enhance the activity of the central nervous system.

The first use of caffeine is thought to have been from tea in China as early as 1000 B.C. (2)

Caffeine from coffee was likely discovered later in Ethiopia around 850 A.D., where local lore tells an amusing story about a shepherd who noticed the hyper behavior of his goats after they ate berries or “beans” from the Coffea arabica plant.

The drug is a bitter-tasting small molecule known scientifically as 1, 3, 7-trimethylxanthine. It’s both water and fat-soluble and easily crosses the intestine and brain barriers.

Caffeine occurs naturally in at least 60 plants, including coffee, tea, kola nuts, and cacao. It is also produced in labs synthetically, generally what is used in energy drinks and medications. (3)

How Does Caffeine Work?

Once caffeine enters the digestive system, it absorbs easily through the intestine wall. (4)

It then makes its way into the liver, where it is broken down into three new molecules – theobromine, paraxanthine, and theophylline. Each of these metabolites performs their own unique stimulant activities throughout the body.

Most notably, the molecules make their way to the brain and work together to block adenosine receptors.

Adenosine is a chemical that usually attaches to the brain, signaling the body to get sleepy. The caffeine blockers do not allow this to happen, keeping the person awake.

While the molecules are attached to these receptors, they signal the brain to release neurotransmitters like dopamine, increasing brain activity, alertness, and ability to focus.

Adenosine receptors are found throughout the body, where the caffeine derivatives have similar stimulating activities.

This includes increasing the rate of the heart and digestive system, lung diaphragm capacity, and kidney function.

It takes about 30–45 minutes for caffeine to reach its highest concentration in the bloodstream once it’s swallowed. It then takes about 2.5–4.5 hours for the caffeine to reduce to half of that level. (5)

This timeline can vary greatly from person to person, depending on their caffeine sensitivity.

Potential Benefits of Caffeine

Because caffeine has been so popular for so long, it is the topic of countless studies. A lot of research has resulted in caffeine’s use as a medicine, often improving the quality of life for people when used correctly.

Keep in mind that caffeine is sometimes falsely credited with providing certain health benefits when instead, the advantages may be a result of the diverse components in coffee or tea.

Premature Infants with Apnea

Premature infants’ lives can benefit from caffeine as a medicine.

Sometimes preemies experience a condition called apnea, in which their breathing stops for 15–20 seconds, which leads to dangerous dips in oxygen and heart rate.

Prescribing small doses of caffeine has been proven to help these babies better control their breathing patterns. (6)

Headache and Pain Medication Enhancement

Headache and pain medications are often enhanced with the use of caffeine.

Studies show that combining caffeine with acetaminophen, aspirin, or ibuprofen is more effective than taking the medications by themselves. (7)

Some research shows that caffeine reduces the need for pain medication by 40%. (8)

Sports Performance and Fat Burning

Sports performance and fat burning can be enhanced with caffeine. (9)

A review of studies concluded that moderate caffeine intake can improve the use of fat as energy, depending on the fitness of the person exercising. (10)

Athletes are aware of the drug’s effects on performance. It’s estimated that three out of four athletes use caffeine before or during their sport, and use is highest for endurance athletes. (11)

Neurodegenerative Disorders

Neurodegenerative disorders such as Alzheimer’s and Parkinson’s diseases may be improved with the use of caffeine. (8)

In several studies, the motor skills in patients with Parkinson’s were improved with the stimulant.

In Alzheimer’s disease, caffeine seems to be protective against plaque buildup in the brain’s blood vessels and improves cognitive impairment.

One study showed that people who consumed 3–5 cups of coffee in midlife have a 65% less chance of getting forms of dementia later in life. (12)

Potential Risks of Caffeine

While caffeine has its perks, it’s not necessarily good for everyone. Sensitivity to caffeine ranges from person to person and can change during different life stages.

Just like any chemical, too much caffeine can be dangerous.

Caffeine Supplements

Caffeine supplements are available in wide ranges of potency on the market, and at least two deaths have been associated with pure caffeine powder. (13)

Just one tiny teaspoon of the powder has the equivalent of about 28 cups of coffee, which is considered a toxic dose.

The Food and Drug Administration (FDA) is trying to regulate pure caffeine powders strictly. The FDA has issued warnings to the public and guidance for supplement companies. (13, 14)

Increased Blood Pressure

Caffeine may increase blood pressure in sensitive people.

Scientists think this may be caused by a combination of caffeine’s ability to constrict blood vessels.

It may also be because caffeine causes the body to release adrenaline, which raises blood pressure.

People who are diagnosed with hypertension should discuss caffeine intake with their doctor.

Heart Palpitations

Heart palpitations may occur after getting too much caffeine, especially in people who are sensitive to the drug. (15)

This can be an uncomfortable and even frightening feeling, like the heart is fluttering, missing beats, or beating too hard and fast.

People who have these symptoms are generally advised to cut back on caffeinated beverages.

However, a recent very large study has found that people who drink moderate amounts of caffeine from coffee daily may decrease the risk of dangerous heart arrhythmia. (16)

Pregnancy

Mothers may be advised to avoid or cut back on caffeine during pregnancy. The size and structure of the caffeine molecule allow it to pass through the placenta to the baby.

One study showed that pregnant moms who consumed more than 200 mg of caffeine daily had a higher risk of miscarriage. (17)

Pregnancy can also change the rate of a mother’s caffeine metabolism, especially during the last trimester of pregnancy. (18)

While caffeine normally stays in the adult system for 3–6 hours, it tends to remain in the body for up to 15 hours in pregnant moms, possibly resulting in sleep disruptions.

Breastfeeding

Breastfeeding moms may find that their newborn infants are sensitive to caffeine, disrupting sleep for both baby and parents. (19)

Caffeine passes easily into the breastmilk. Although the drug generally reaches the baby in small quantities, it may be 120 hours before half of the caffeine the baby ingests is out of a newborn’s system.

In general, most infants can metabolize caffeine as quickly as an adult by the time they are 3–5 months old. However, the impact of caffeine on children’s health isn’t well understood. (20)

If mom keeps caffeine intake to under 300 mg, or less than about 3 cups of coffee, the caffeine content in their breastmilk should be within safe doses for infants. (21)

Caffeine Sources

Caffeine is found naturally in over 60 plants and can be made synthetically in laboratories for use in medications, supplements, and beverages.

Here are some examples of caffeine sources commonly consumed in the United States, along with their caffeine content. Keep in mind that caffeine content from natural sources can vary. (22)

Safety, Side Effects, and Dosage

Caffeine from natural sources like coffee and tea is generally regarded as safe (GRAS) by the FDA. (24)

However, some supplement products, including some supplement drinks, may contain more caffeine than the product reports on the label.

The safe levels of caffeine can vary greatly depending on a person’s size, ability to metabolize caffeine, and individual sensitivity to caffeine.

With this in mind, up to 400 mg of caffeine daily is considered safe for most people. (25)

Moderate caffeine intake of less than 200 mg per day seems to be safe for pregnant moms and their babies, but it’s best to discuss the latest research with your doctor. Sensitivity to the drug may increase during the third trimester. (17)

Toxic levels of caffeine have been estimated at around 1,200 mg. This is the amount in one small teaspoon of pure caffeine powder. (18)

Toxicity symptoms include rapid heart rate, heart rhythm abnormalities, confusion or altered mental status, and seizure.

Ingesting 10,000 mg or more is considered life-threatening.

The consumption of caffeine, especially from energy drinks, is a concern in adolescents. According to the CDC, 1,499 kids between the ages of 12–17 went to the emergency room related to energy drink consumption in 2011. (26)

It’s unclear if there is a safe amount of caffeine for children.

Common side effects of caffeine and signs that you may have had too much include:

• Restlessness or inability to sleep
• Jittery or shaky feeling
• Anxiety
• Rapid heart rate
• Stomach upset or nausea
• Headache

People with conditions such as heart disease, high blood pressure, and anxiety should avoid caffeine.

Frequently Asked Questions

The Bottom Line

Caffeine is a psychostimulant drug that has been consumed by humans from plant foods for thousands of years.

As one of the most frequently studies drugs, scientists have found medical uses for caffeine that improve the quality of life for many people, from infants to athletes.

Like any drug, caffeine use comes with risks. The more recent marketing of caffeine supplements in pure form and in beverages has increased the incidents of toxicity and even death.

Some people are more sensitive to caffeine than others, and the use of caffeine is not recommended for everyone, including pregnant women and children.

When it comes to health, if it’s consumed in moderate amounts as nature intended, caffeine is generally safe and may even improve the quality of life.