How Does Caffeine Affect Your Body?

Can caffeine affect your body? The short answer is yes. In this episode and in honor of Caffeine Awareness month, we will discuss how caffeine affects your body and its effects after consuming it for a long time.

Most Americans use caffeine daily but don’t even know what it is or what caffeine exactly does. About 85% of people in the US consume at least one caffeine beverage/per day [1]. 

What is Caffeine, and Can Caffeine Affect Your Body?

When someone says caffeine, we immediately think of coffee. And while coffee has caffeine, it’s not it. Caffeine is a bitter-tasting, white, and odorless powder.

It is naturally found in the fruit, leaves, and beans of coffee, cacao, and guarana plants. The truth is that caffeine is added to almost all kinds of food and drinks. 

It is also a Central Nervous System Stimulant and one of the most common psychoactive drugs used globally. In addition to that, caffeine is the only legal, unregulated psychoactive drug. 

So, the next time you wonder why you are addicted to caffeine, it’s because of its psychoactive properties. 

How Caffeine Acts in the Body

The way caffeine works are thought to be mediated by several mechanisms: 

• Antagonism of adenosine receptors
• The inhibition of phosphodiesterase
• Release of calcium from intracellular stores
• The antagonism of benzodiazepine receptors

The most common one is that it blocks the action of adenosine on its receptors and prevents the drowsiness associated with it.

Adenosine Antagonist 

When a person is awake and alert, small amounts of adenosine are present in CNS. Over time, adenosine accumulates in the neuronal synapse by being constantly awake. 

Once adenosine increases, it binds and activates the receptors found on specific CNS neurons. 

When activated, the adenosine receptors produce a cellular response that increases drowsiness. 

What Happens to Adenosine?

• When caffeine is consumed, it antagonizes the adenosine receptors. Caffeine prevents adenosine from activating the receptor by blocking the receptor site.
• Therefore, caffeine temporarily prevents or relieves drowsiness and maintains or restores alertness [2].
• Caffeine also increases energy metabolism throughout the brain but can also decrease cerebral blood flow, which induces relative brain hypoperfusion [3].

Due to the blocking of adenosine inhibitory effects through its receptors, caffeine indirectly affects the release of the following [4]:

•  norepinephrine
• dopamine
• acetylcholine
• serotonin
• glutamate
• gamma-aminobutyric acid (GABA)
• neuropeptides 

Inhibition of Phosphodiesterase

Phosphodiesterase inhibition prevents the ability to break down cAMP and cGMP. The levels inside the cell increase, therefore, leading to a decrease in calcium levels in the cell. It leads to vasodilation and smooth muscle relaxation [5].

Caffeine is a vasoconstrictor and works mainly in your heart and brain. However, it vasodilates your peripheral and bronchial vessels as well.

Releases Calcium from Intracellular Storage

Caffeine affects the body by taking calcium from the bone and introducing it into the bloodstream. 

Most studies show that this amount is not substantial enough to cause osteoporosis, and the calcium loss can be replaced by adding some milk. 

Benzodiazepine Receptor Antagonist 

Studies show that caffeine has weak antagonistic properties at the benzodiazepine receptor sites. The reaction, however, can be due to adenosine suppression [6]. 

SNS vs. PNS

The parasympathetic nervous system (PNS) controls homeostasis. The PNS maintains the body at rest and is responsible for the “rest and digest” functions. 

Similarly, the sympathetic nervous system (SNS) controls the body’s responses to a perceived threat and is responsible for the “fight or flight” response. 

Effects of Caffeine on the Body

Caffeine’s direct effects on the body are due to the inactivation of adenosine receptors. It leads to greater stimulation of the SNS, causing various effects. Here are the most common effects of caffeine on the body: 

Increase in alertness

• The stimulating effects of caffeine cause alertness right away. In addition to that, it can also temporarily relieve drowsiness and fatigue.

Decreased suicide risk – check with your doctor

• One study found that the mood-enhancing effects of caffeine were linked to a percent lower risk of suicide in participants.

Increased heart rate and blood pressure

• Caffeine affects your body by resulting in a rapid heartbeat. In that case, this may be a concern if you have a preexisting heart issue. You may notice arrhythmias whenever you have caffeine.
• It can also temporarily raise your blood pressure. The effects may be especially noticeable if you have caffeine during or right before exercise or other physical activity.

Confusion

• Too much caffeine can overstimulate the brain, leading to confusion or the inability to focus on one task.

Headache

• A headache can occur from either too much caffeine or as a symptom of caffeine withdrawal. But specific amounts can help with headaches.

Irritability

• When your body is used to caffeine, you can experience irritability as a symptom of withdrawal.

Heartburn

• The acidity of certain caffeinated products, like coffee and soda, may cause heartburn.

Diarrhea

• Caffeine can also help regulate your bowel movement, but too much intake can cause opposite effects like diarrhea.

Fertility/Pregnancy

• Some women who consume too much caffeine might experience difficulties getting pregnant. If you’re trying to get pregnant, It’s best not to consume more than 300 mg per day.
• Consuming too much caffeine affects your body during pregnancy, which may cause miscarriage and developmental issues in newborns. 
• It’s recommended that pregnant women consume no more than 200 mg of caffeine per day. It equals about one 12-ounce cup of coffee.

Bones

• Caffeine prevents calcium absorption in the bones, increasing your risk of osteoporosis. As you get older, your bones may break more easily.

Urination

• Frequent urination may be experienced when you consume too much caffeine. Caffeine affects the body as a diuretic, and long-term use of high amounts of caffeine may increase bladder instability.
• It can worsen the risk for those already experiencing bladder problems.

Jitters

• Caffeine can give you the jitters if you’re not used to it. If you have an anxiety disorder or sleep disorder, caffeine may make it worse.

Metabolization of Caffeine 

• Caffeine from coffee or other beverages is absorbed by the small intestine within 45 minutes of ingestion and distributed throughout all bodily tissues.
• ​​Peak blood concentration is reached within 1–2 hours.
• Caffeine’s biological half-liver varies from individual to individual, roughly between 2 and 7 hrs.
• It can also be absorbed rectally. However, the rectal route has a 30% lesser absorption rate [7].

The FDA has cited 400 milligrams a day for healthy adults—about four or five cups of coffee—as an amount not generally associated with complications.

To watch the full Episode 92, click here for more 👇

TIME STAMPS:

0:00 Intro
0:50 Plugs
2:16 Episode Intro
6:07 The only unregulated psychoactive drug
10:19 How Caffeine Acts in the Body
10:25 Adenosine Antagonist
13:03 Caffeine decreases cerebral blood flow
15:39 Inhibition of Phosphodiesterase
16:29 Releases Calcium from Intracellular Storages
18:52 Benzodiazepine Receptor Antagonist
23:13 A possible reason why you are irritable
25:00 Effects of Caffeine
25:10 Increase in alertness
29:18 Tips on setting your body clock
33:07 Estimating time when to take caffeine
39:32 Frequent urination
39:58 Too much caffeine can cause diarrhea
40:41 Decreased suicide risk
46:33 Caffeine as medicine