5 Effects of Caffeine on Your Body (Explained!)

Caffeine, the active ingredient in tea and coffee, is one of the world's most popular psychoactive substances. Humans have been brewing energy drinks like coffee, tea, and other beverages containing the substance for millennia. Many people rely on caffeine in their energy drinks to help them stay alert and focused.

As you can imagine, caffeine intake profoundly impacts most healthy adults. When taken in moderation, the effect of caffeine on your body is beneficial, with the drug acting like a mild stimulant of the central nervous system.

Caffeine has a range of effects on your body, from affecting your blood pressure to stimulate the central nervous system. It can also elevate your heart rate and increase mental alertness and energy. The effects of caffeine can last for a few hours, depending on how your body metabolizes the drug.

In this article, we will learn in detail about this very popular psychoactive substance and understand the effects of caffeine consumption on your body. We will also shed light on how you can maximize the beneficial effects of caffeine while keeping the side effects at bay.

How Much Caffeine Is Safe to Take in a Day by Healthy Adults?

Chemically, caffeine belongs to a group of phytochemicals called methylxanthines. In its natural form, caffeine tastes bitter and occurs in varying concentrations in several plant species.
All methylxanthines, including caffeine, are considered central nervous system stimulants. Remember, the central nervous system consists of the brain and spinal cord, and caffeine consumption stimulates both components.

As with any stimulant, there is a safe limit associated with energy drinks containing caffeine as well. Several studies show that indulging in a cup of coffee here and there can be good for your brain. There is also ample evidence that caffeine consumption can improve memory, reasoning, attention, and mood when taken in moderation. No wonder a cup of caffeinated drink like coffee or tea can put you in a good mood!

According to multiple studies, the dose range can vary between 30 to 400 milligrams a day to achieve the best results from caffeine. The vast range in dosage is because some people can metabolize caffeine faster than others. Also, you can build up caffeine tolerance over time. When you develop tolerance to caffeine, you need more caffeine to elicit the same level of response.

For instance, if someone only takes a morning cup of coffee the whole day, they might see the effects of caffeine at lower doses. On the other hand, if you drink a lot of coffee, you might not know the impact of caffeine until you reach a higher amount.

How Do Caffeine Energy Drinks Work at a Cellular Level?

At the molecular level, caffeine is an adenosine receptor antagonist. In other words, caffeine blocks the effects of adenosine (a chemical present in your cells) on neurons. Adenosine is a naturally occurring substance in your body with receptors on various body organs, including nerve cells or neurons.

When adenosine binds to its receptors on your neurons, it suppresses their firing. The suppression of the neuron will make you feel more tired, less alert, and fatigued. When you consume too much caffeine, it competes with adenosine molecules for a place on the receptors.

Caffeine Prevents Adenosine From Acting

As caffeine acts to prevent the adenosine from binding to the receptors, the effects of adenosine are nullified, and you feel less tired and more energized.

Adenosine is generated in your body as your body utilizes adenosine triphosphate (ATP) to create energy. So, as you keep burning ATP molecules, your cells start accumulating adenosine, and you start feeling tired and low on energy.

As caffeine acts to prevent the interaction of adenosine with its receptors on the neurons, you don’t see the tiring effects of adenosine and get a surge of energy. So, the next time you feel refreshed and reenergized after consuming energy drinks, you have the caffeine to thank.

What Are Some of the Effects of Caffeine on Your Body?

Caffeine affects multiple organs and organ systems of your body to create quite a complex effect on your body. Some of the effects of caffeine on various organs of your body include the following.

1. Stimulates the Central Nervous System

Caffeine acts as a central nervous system stimulant. It has stimulatory effects on both your brain and spinal cord. The caffeine molecule exerts its stimulatory effect by blocking a specific receptor called the adenosine receptor on your neurons.

The adenosine receptors are proteins that relay the information carried by adenosine to the brain's neurons. Adenosine is an inhibitory molecule that decreases the activity of the neurons, making them sluggish. When it is in your nervous system, your neurons are less active, and you feel tired.

When adenosine binds to its receptors, the neuronal firing rate decreases, leading to a depression of your central nervous system or CNS.

Caffeine prevents this action of adenosine by binding to the same receptors and preventing adenosine from interacting with them. The adenosine molecule can't convey the depressing signals, and your neurons remain active. You feel more alert and fresh, even when much adenosine is in your central nervous system.

It is this effect of caffeine that makes it feel like a stimulant and the reason it is a primary ingredient in several energy drinks.

That said, the effects of caffeine are not always beneficial. If you consume too much caffeine, you can experience overstimulation, jitteriness, and anxiety. Too much caffeine consumption can also lead to sleep deprivation and interfere with REM deep sleep and high blood pressure.

In some individuals, caffeine is also known to precipitate panic attacks. Sleep disturbances can lead to daytime drowsiness and fatigue.

If you have chronic sleep deprivation due to too much caffeine, it might lead to cognitive impairment, high blood pressure, and may even lead neurodegenerative effects.

2. Affects the Cardiovascular System

Caffeine also influences the cardiovascular system. At moderate to low doses, caffeine intake can improve blood flow and blood pressure and even reduce the risk of cardiovascular disease. However, too much caffeine intake can negatively affect the cardiovascular system, including increased blood pressure and heart disease risk.

Caffeine exerts its cardiovascular effects by acting like a vasoconstrictor resulting in high blood pressure. In other words, it constricts the blood vessels, reducing their lumen and increasing blood pressure.

On the other hand, caffeine energy drinks can also relax the smooth muscles of the walls of the blood vessels. Relaxing the smooth muscles can improve blood pressure and blood flow to various organs like the heart and brain.

The muscle-relaxing effect of caffeine is beneficial in treating various health conditions, including migraine headaches. However, too much caffeine can cause hypertension and jitters, especially during caffeine withdrawal.

Studies have also shown that regular caffeine intake in moderation can reduce the risk of cardiovascular disease. Caffeine is thought to improve the endothelial function of the blood vessels and thereby act to prevent cardiovascular diseases.

Caffeine intake prevents blood vessel rigidity, so it can improve their ability to contract and relax when required.

3. Improves the Function of the Digestive System

Caffeine has an effect on the gastrointestinal system as well. When consumed in moderate amounts, caffeine can stimulate the oxyntic cells of your stomach to release hydrochloric acid.

The production of acid stimulates the smooth muscles of the gastrointestinal system to contract, improving gastric motility.

Caffeine intake can, thus, increase the motility of your gastrointestinal tract, helping you to void your bowels. If you are experiencing mild constipation, a cup of coffee can help.

However, too much caffeine is not good for your gastrointestinal health. If you consume too much caffeine, the overproduction of gastric acid may cause acid reflux and hyperacidity.

Consuming moderate amounts of caffeine energy drinks is important to benefit the digestive system. Consuming too much caffeine can also result in diarrhea in some people. Stopping caffeine abruptly can cause caffeine withdrawal, which might lead to constipation.

4. Increases Blood Pressure

High blood pressure is one of caffeine's most important effects on your body. As caffeine acts as a potent vasoconstrictor, it can reduce the lumen of your capillaries, resulting in high blood pressure.

Studies have shown that most healthy adults consuming a cup of caffeinated beverages containing about 200 mg of caffeine intake can increase their blood pressure by as much as 10 points.

Genetics also plays a crucial role in determining the effect of caffeine intake on your blood pressure. If you are prone to hypertension or have been diagnosed with hypertension, too much caffeine can produce a sharper rise in your blood pressure.

5. Impacts on Renal Function

Kidneys are vital organs for maintaining your body's fluid and electrolyte balance. Consuming caffeinated beverages can impact the kidneys in two following ways:

Increased blood flow

Caffeine can increase the blood flow to most healthy adults' kidneys, helping them filter more blood than usual. As more blood is pumped through the kidneys, you tend to produce more urine when on caffeine. High blood pressure due to caffeine intake also plays a role in increasing urine output.

Inhibition of water uptake

Another way in which caffeine intake can affect renal function is by reducing the capacity of your kidneys to reabsorb water. Water reabsorption is controlled by a small molecule in the kidney called cyclic AMP (cAMP).

When cAMP is present in larger amounts, kidneys don’t reabsorb water, and you tend to produce more urine output. Caffeine helps increase the kidneys' cAMP level by blocking the enzyme responsible for breaking it down.

As the level of cAMP increases, the kidneys start producing more urine and absorbing less water. Taken together, too much caffeine causes more urine production or diuresis.

What Are the Health Benefits of Caffeine?

When you consume it in moderation, caffeine can have various health benefits as well. Doctors have been using caffeine to treat neurological conditions, including Parkinson's and Alzheimer's disease, for years.

Here are a few health benefits of consuming caffeinated beverages by most healthy adults, albeit in moderation.

Improved cognitive function

Several studies have shown that low doses of caffeine positively improve the brain's cognitive function. When you consume caffeine, it improves your alertness, concentration, and even memory. These stimulatory effects of caffeine are more pronounced when you are tired.

Hence, serving caffeinated beverages can help you focus and study better.

Increased energy and performance

Caffeine is known to be a great pre-workout supplement and is a significant component in several supplements. It stimulates you, filling you with the energy to perform better.

You must have seen many people using caffeinated drinks to improve their energy levels throughout their workouts.

Weight loss

Caffeine can also help with weight loss through two mechanisms. Firstly, low doses of caffeine can improve your metabolism and promote fat burning. So, when you consume caffeine, your body consumes more calories even when idle, leading to accelerated weight loss.

Secondly, low doses of caffeine reduce appetite and increase feelings of fullness, which might lead to a reduction of caloric intake and help you lose weight. That said, you should avoid too much caffeine as the harmful effects outweigh the benefits at higher dosages.

Reduced Risk of Certain Diseases

Studies have shown that consuming caffeine in moderation can reduce the risk of certain neurodegenerative diseases, such as Alzheimer's disease and Parkinson's disease.
Caffeine prevents the accumulation and buildup of amyloid-beta plaques in the brain, which are associated with Alzheimer's disease. Caffeine also improves dopamine levels in the brain, which may help reduce the risk of Parkinson's disease.

The recommended daily intake of caffeine varies by individual. Still, adults should consume no more than 400mg of caffeine daily, roughly equivalent to four cups of caffeinated beverages.

Enhanced Mood

When consumed in moderation, caffeine has been shown to have a mood-elevating effect. Caffeine has been shown to increase neurotransmitters such as dopamine and norepinephrine levels in the brain, leading to feelings of happiness, pleasure, and alertness.

In addition, caffeine can also reduce the symptoms of depression and anxiety. Some studies have suggested that regular caffeine consumption may be linked to a reduced risk of anxiety and depression.

Too much caffeine intake can negatively affect mood, including increased anxiety and irritability.

Caffeine Withdrawal Symptoms

While caffeine has beneficial effects, it can cause dependence, and when you stop consuming caffeinated drinks, it can result in caffeine withdrawal symptoms. Some of the most prominent caffeine withdrawal symptoms include the following:

• Headaches
• Fatigue
• Difficulty concentrating
• Nausea, vomiting, and muscle tremors or stiffness
• Sleep deprivation

The caffeine withdrawal symptoms last for two to nine days in most healthy adults.

Takeaway: A Cup of Joe Is All You Need!

Caffeine has been around for a long time in teas, coffee, and several other beverages. While primarily a central nervous system stimulant, caffeine can significantly affect your body.
Caffeine affects several body organ systems, from improving your mood and energy levels and increasing your blood pressure to having a neuroprotective effect.
When consumed in moderation, the beneficial effect of the stimulant outweighs its bad effects. It can be an excellent agent to rejuvenate your CNS and boost energy when needed.
If you want to look at your brain's functions in-depth, please watch this video.