Is Caffeine Bad for You? An RD Explains

Though caffeine is a natural plant-based compound that has been used since ancient times, it seems more present than ever in our food and beverages. It’s readily available in natural sources like coffee, teas, and chocolate, but you can now find caffeine in places you might not expect or notice. 

A quick trip through a grocery store can lead you to caffeine in items such as chewing gum, chocolates fortified with extra caffeine, sparkling waters, energy gels and shots, and dietary supplements. And did you see that line of charged lemonades at Panera? They’re caffeinated and sweetened.

Moderate doses of caffeine are generally safe to consume and even have some modest benefits. But, caffeine sometimes has negative effects on health by increasing anxiety, causing jitteriness, or disrupting sleep — and some people are more sensitive to its effects than others. 

If you’d like to reduce your caffeine intake to stay within safe parameters or improve your overall health, we offer tips and strategies to try. 

What Is Caffeine?

Caffeine is a natural substance found in plants. It’s a dietary component that acts as a stimulant to the nervous system. The most well-known feature of caffeine: it typically makes people feel more alert and more awake, as any sleep-deprived new parent or night shift worker can tell you. 

While caffeine is naturally found in many plants, it was first extracted from cocoa beans and ground into a powder form in the 1820s by a German scientist. The earliest evidence of coffee drinking is from the 15th century in Yemen, but tea was used in the Tang Dynasty of China in 618–907 AD because it was thought to prolong life.

Sources of Caffeine

Caffeine is naturally found in plant sources such as cocoa beans, coffee beans, and guarana seeds. According to the Dietary Guidelines for Americans, most caffeine intake in the United States today comes from beverages such as coffee, tea, and soda. 

The top food and beverage sources of caffeine, according to Food Insight, are:

In addition, dietary supplements, such as pre-workout or weight loss formulas, often contain added caffeine. Use caution when using these supplements and make sure to read the ingredients labels carefully, as caffeine may be present in more than one of the ingredients.

How Caffeine Is Digested and Metabolized  

After you eat or drink caffeine-containing foods, beverages, or supplements, it takes about 45 minutes for most of the caffeine to absorb. Caffeine is usually absorbed in the GI tract, and peak amounts are found in the blood within 15–20 minutes of consuming it. Most of the caffeine is eventually broken down by the liver.

On average, caffeine has a half life of about 4–5 hours for most people, which means that half of the caffeine in your body is reduced within that time. The half-life time varies based on age, pregnancy, liver function, and medications such as oral birth control. The rate of absorption can also vary depending on what foods you had at the same time, such as if you drank black coffee on an empty stomach or had a Coke Zero with a full meal.

Safe Intake Levels of Caffeine

According to a 2014 study, the average caffeine intake in the United States is about 165 milligrams (mg) per day across all age groups. A review article published in 2018 found that these caffeine guidelines are likely safe and not associated with adverse effects:

• 400 mg per day for healthy adults

• 300 mg per day for pregnant women

Note that caffeine passes from mother to baby in small amounts in breast milk. The Dietary Guidelines for Americans for 2020–2025 suggest that breastfeeding mothers consuming up to 300 mg per day does not adversely affect breastfed infants. 

Children under 12 are not supposed to consume any caffeine.

Four-hundred milligrams per day of caffeine is the equivalent of about four 8-ounce cups of regular coffee. Even though intake of ~400 mg per day of caffeine is likely safe for most healthy adults, some people are more sensitive to caffeine. More sensitive people may experience some unpleasant side effects such as headaches or increased anxiety at lower daily doses. As always, it’s best to follow your body’s signals to determine if any amount of caffeine works for your mental health and body.

Benefits of Caffeine

Caffeine intake has likely stayed relevant for centuries due to its ability to boost energy and help people stay awake when tired.

Other benefits of caffeine: 

• Increases mental alertness
  

• Decreases fatigue and tiredness 

• Decreases reaction times

• Improves exercise performance 
  

• Contains antioxidant and anti-inflammatory properties, and may help prevent certain diseases when consumed from coffee and tea 

• Treats pauses in breathing in premature infants
  

• May reduce pain
  

Is Caffeine Bad For You? Downsides to Caffeine

According to the FDA, the following symptoms can result from taking in too much caffeine:

• Shakiness or jitters

• Anxiousness

• Disrupted sleep patterns

• Increased heart rate

• Nausea or GI distress

• Headaches

• Feeling unhappy

While the above symptoms are unpleasant, they’re usually temporary. In large doses, caffeine can also have toxic, potentially life altering effects such as seizures, abnormal heart rhythms, losing consciousness, and even death.

For your safety, avoid taking in large doses of caffeine rapidly and stick to the ~400 mg/day maximum guideline. The FDA estimates that toxic effects are more likely if ~1200 mg of pure caffeine is consumed in a short period of time. This is more likely with dietary supplements or pure caffeine powders or liquids. For comparison, 1000 mg of caffeine is equivalent to about 100 cups of coffee. 

Often, sources of caffeine also contain added sugar or fat and may not align with some of your other health goals. For example, a grande pumpkin spice latte from Starbucks contains 390 calories, 50 grams of sugar, and 14 grams of fat. An indulgent latte is a very satisfying treat and perfectly OK to drink on occasion, but it would be difficult to fit into a healthy diet on a daily basis.

How to Reduce Caffeine Intake

Caffeine intake below 400 mg per day is safe for most adults but quitting or reducing your regular caffeine intake might make you feel better if you start experiencing any negative side effects after consuming it. Eliminating caffeine could reduce anxiety, improve your overall mood, or help you sleep more soundly.

Whether you’re a regular coffee drinker or consume regular amounts of caffeine from another source, it’s best to reduce your intake gradually. Though it may be tempting to quit caffeine cold turkey, withdrawal symptoms are possible if you’re used to consuming large amounts of caffeine per day. These symptoms can include headaches, irritability, altered sleep, and increased anxiety.

Try these tips to reduce your caffeine intake over time:

1. Get clear about how much caffeine you currently take in. Track your coffee and caffeinated beverage intake for a few days to understand how much you’re drinking. It’s easy to mindlessly overlook the extent of your intake if you're sitting next to a filled coffee pot all day or a refrigerator full of energy drinks. Check any dietary supplements you might take, especially workout-focused supplements, to see if they contain caffeine, too.

2. Optimize your sleep routine. If you become more disciplined about going to bed in time to sleep for 7–9 hours, you may not need to rely on caffeine as much to stay awake the next day.

3. Set a time limit. Since the half life of caffeine is about 4–5 hours, caffeine’s effects last far beyond when you consume it. Stop drinking caffeine each day at least six to seven hours before your bedtime. Try a firm time limit each day, such as not drinking caffeine after noon or 1 pm.

4. Switch to half caff. Ask a barista to make your daily latte with half the amount of espresso it would normally contain. At home, try mixing decaf and regular coffee 1:1 for your morning brew. Some brands even sell coffee beans with half the amount of caffeine as normal.

5. Use water to quench your thirst instead of caffeinated drinks. Sip a glass of water in the morning before having coffee, and aim to drink one caffeine-free beverage before each caffeinated beverage you would typically drink. This should make you more mindful before you drink another glass of coffee or tea, and has the added benefit of increasing your hydration levels, too.

6. Substitute other hot drinks. Instead of a hot cup of coffee, try a hot cup of herbal tea or a lower-caffeine green tea instead. Some people enjoy sipping hot lemon water as well.

7. Try sparkling water. If you think you’ll miss the carbonation from soda or energy drinks, sparkling flavored waters might satisfy the same craving. Many brands and flavors of sparkling waters exist so you should be able to find one you enjoy.

8. Take an exercise break. If you hit a midafternoon slump during your workday, stand up from your desk and go for a quick walk or do some light stretches. If possible, step outside for a few minutes so the fresh air can revive you.

9. Consider if you might need a snack instead of a caffeinated beverage. A balanced snack such as an orange or banana paired with a protein (cheese stick, an ounce of almonds or other nuts, a serving of turkey jerky) will provide sustained energy instead of the quick boost that you normally get from your afternoon latte or energy drink. 

The Bottom Line 

For most healthy people, it’s safe to drink 400 mg of caffeine each day. But, you might feel better in the long run if you reduce or quit caffeine since it can increase anxiety and irritability, cause jitteriness, and impact your sleep. If you typically drink sugary soft drinks and teas or indulgent coffee drinks, you’ll improve the quality of your diet by switching to water.