Caffeine Effects and Risks » The Unclouded Path

If you’re like most people, you probably start your day with a cup of coffee or tea to get some caffeine into your system. Just about everyone knows that one of the effects of caffeine is increasing your alertness. It also has a few surprising beneficial side effects as well. But use too much, and it can cause a whole host of unpleasant and even dangerous problems.

What Is Caffeine?

Caffeine is classified as a stimulant and a psychoactive drug. This means it increases the activity of the central nervous system (in this case, the brain), leading to changes in your perception, thinking ability, mood, and behavior. In fact, it’s the world’s most popular psychoactive drug.

It occurs naturally in the seeds, nuts, or leaves from a variety of plants native to Africa, East Asia, and South America. For example, the most widely known ones are the coffee plant (coffee “beans” are its seeds), the kola tree (kola nuts were originally used to give cola flavor and caffeine), and the tea plant. Small quantities of caffeine are also in the seeds of cacao plants (used to make chocolate).

Caffeine also stimulates parts of the autonomic nervous system, a part of the peripheral nervous system. The autonomic nervous system regulates breathing, heart rate, and digestion, among other things.

How Much Caffeine Can You Safely Consume?

For normal adults, the recommended maximum daily intake of caffeine is about 400 mg. For pregnant women, it’s about 200 mg. But for children, it’s a bit more complicated. Their daily maximum is about 2.5 mg per kilogram of body weight. In order to avoid problematic side effects, it’s also important that you don’t consume more than 200 mg in any one sitting.

Here’s a list of common sources of caffeine and the amount they contain:

Coffee (207 mL (7 oz) serving): 80-175 mg
Decaf Coffee (207 mL (7 oz) serving): 5-15 mg
Espresso (44-60 mL (1.5-2 oz) serving): 100 mg
Tea (177 mL (6 oz) serving): 22-74 mg
Soft Drinks (355 mL (12 oz) serving): 0-55 mg
Yerba Mate (240 mL (8 oz) serving): 50-130 mg
Energy Drinks (240 mL (8 oz) serving): 50-160 mg
Cocoa Drink (240 mL (8 oz) serving): 2-7 mg
Hershey’s Milk Chocolate (43 g (1.5 oz) bar): 10 mg
Hershey’s Dark Chocolate (43 g (1.5 oz) bar): 31 mg

Beneficial Caffeine Effects

Caffeine has a number of useful effects, which is probably why caffeinated beverages are so popular. Here’s a list of its benefits:

It makes you more awake. Caffeine interferes with adenosine receptors in the brain. Normally, adenosine builds up throughout the day because of cellular activity. This buildup makes you feel tired, and it’s one of the ways the body knows when it’s time for rest. But caffeine blocks adenosine receptors, so they don’t detect the buildup. By increasing wakefulness, caffeine also improves a lot of other cognitive functions like reaction time, motor coordination, concentration, and short-term memory.
Caffeine slightly increases your basal metabolic rate (metabolic rate at rest). But the effect is only about 11%, so it’s not a game-changer.
It improves physical performance. During exercise, it delays exhaustion and muscle fatigue. This improves performance in both aerobic and anaerobic sports. These effects are a result of caffeine’s ability to increase fat burning (leading to less reliance on sugar-based energy) and neural function. This increased metabolic performance also improves muscle power and reduces perceived exertion.
It may reduce the risk of Alzheimer’s disease. There is some evidence that caffeine interferes with the production and activities of harmful proteins that cause the disease (amyloid beta and disfigured tau proteins). But it’s still an area of ongoing research.
It may reduce the risk of Parkinson’s disease. There some evidence that the risk of Parkinson’s goes down with higher caffeine consumption. But it’s still an area of ongoing study, and it’s not clear why caffeine has this effect. One hypothesis is that it protects dopamine-sensitive neurons by interfering with adenosine receptors.

Risks of Caffeine Consumption

You might be tempted to consume even more caffeine because of its benefits, but don’t. Using too much or using it if you’re especially sensitive to its effects can cause a bunch of unpleasant, even life-threatening, side effects. This is a list of them:

increased blood pressure
increased stomach acid production (can lead to heartburn)
reduced calcium absorption (can lead to bone loss)
increased urine production (caffeine’s only mildly diuretic though, and tolerance to this effect builds up quickly)
digestive problems
anxiety
dizziness
irritability
insomnia
fidgeting and twitching
headaches
rapid or irregular heartbeat

Very serious overdoses can lead to mania, confusion, lack of judgment, delusions and hallucinations, and breakdown of skeletal muscle.

Caffeine is also mildly addictive and you can develop a sort of caffeine dependence with repeated use. This can lead to withdrawal symptoms like headaches, drowsiness, nausea, depressed mood, and increased irritability. But the symptoms go away in about few days of avoiding caffeine.

Consuming Caffeine Safely

Like all beneficial drugs, caffeine needs to be used carefully. Here are some safety tips to remember about consuming it:

Tolerance to caffeine builds up quickly. That means you’ll need more and more caffeine to get the same effects. But resist the urge to increase your consumption. If you feel that you’re not getting the same effects from caffeine as you used to, decrease your usage gradually (to avoid withdrawal symptoms) for a while and then gradually increase it to your previous levels. This will ensure that you don’t overdose on it.
Don’t binge on energy drinks (or any high-caffeine drink). You might want to keep drinking them to stay up all night to work on homework or to study for a test. But it’s an easy way to overdose on caffeine. It’s also counterproductive since you might not be able to think straight the next day.
For tea, the way you brew it changes the amount of caffeine it has. For example, brewing tea for a short amount of time or cold brewing it reduces the caffeine content.
Don’t mix caffeine and alcohol. Contrary to popular belief, caffeine won’t make you sober. It doesn’t reduce the effects of alcohol at all, but it may interfere with your perception of how drunk you actually are. This can lead to over-drinking.
Pregnant or breastfeeding women should limit their caffeine consumption because caffeine can be transferred to the baby through the placenta or milk respectively.
For children and adolescents, caffeine consumption should be reduced or avoided entirely. They can be especially sensitive to caffeine’s effects. The same also goes for anyone who has a problem with its effects.
Certain substances can affect the amount of time caffeine stays in your system. Smoking tobacco reduces it, while birth control pills extend it.
Caffeine can enhance or interfere with the effects of certain medications. For example, it strengthens the effects of some headache medicines. You should talk with your doctor about any possible interactions between caffeine and any medicines you’re taking.
Pay very close attention to how much caffeine you’re using. The median lethal dose (LD₅₀), the dose that will kill 50% of the tested population, for humans is 150-200 mg per kilogram of body weight. For people who have chronic liver disease or whose bodies can’t get rid of caffeine easily due to genetics, it’s even lower. Although it’s not practical to drink enough coffee or tea to reach this amount, for powdered caffeine supplements, this amount can be reached with less than a tablespoon.