The human body absorbs caffeine quickly and reaches its peak effect within two hours, although it may take about nine hours for it to exit the body.
Caffeine is soluble in water and fat, so it enters all tissues of the body, which explains the effect of caffeine on many different parts of the body.
It is preferable for adults not to consume more than 400 mg of caffeine per day (about four cups of coffee), especially since consuming a larger amount may lead to muscle tremors, nausea, headaches, heart palpitations, and even death (in extreme cases).
And if you're thinking about giving up caffeine and wondering what benefits it might offer, here's what the research says:
Brain function
Caffeine withdrawal can cause headaches, fatigue, and exhaustion because the body develops a tolerance to caffeine.
Caffeine binds to a receptor in the brain used by adenosine. Its association with these receptors delays the appearance of fatigue in the body. But over time, brain cells produce more adenosine receptors to enable normal binding of adenosine.
So, when you stop consuming caffeine, there are extra adenosine receptors to bind to. This allows fatigue and exhaustion to appear as normal, with the person feeling more tired than before.
Headaches occur as a result of the absence of caffeine. In the head and neck, caffeine causes blood vessels to narrow, reducing blood flow to the brain.
When you stop drinking caffeine, after about 24 hours, this leads to the blood vessels returning to normal, which causes an increase in blood flow to the brain and causes headaches.
Caffeine only really affects sleep when taken in the late afternoon and evening. This is because caffeine delays the release of melatonin (the hormone that makes us tired) for 40 minutes.
Cardiovascular health
Reducing or eliminating caffeine may treat heartburn and indigestion. Caffeine stimulates acid secretion in the stomach and weakens the lower esophageal sphincter, which controls the reflux of stomach contents into the esophagus, leading to heartburn and indigestion.
Giving up caffeine may also lower blood pressure and reduce heart rate, although other studies have shown little change.
There also appears to be a genetic component to caffeine tolerance and metabolism. This may mean that some people are more affected by caffeine than others, although more research is needed into this link.
Brighter smile
Giving up caffeine may improve the whiteness of your teeth, not directly because of the caffeine, but because tea and coffee contain compounds that stain teeth.
The sugar in energy drinks can also cause damage to your teeth.
Evidence also suggests that caffeinated drinks may reduce the amount of saliva we produce, which normally protects our teeth from damage.
Going to the toilet less often
Caffeine affects the smooth muscles in the intestine, especially in the colon, causing them to contract and stimulating the urge to defecate. Caffeine can also change the consistency of your stool, especially if you drink it a lot, because it affects water absorption.
Reducing caffeine intake may reduce the urge to defecate, and the consistency of the stool may change.
Caffeine also acts as a mild diuretic, because it binds to adenosine receptors in the kidneys, which changes how sodium is exchanged, affecting water retention.
If you are seriously considering removing caffeine from your diet, the best way to do so is gradually.
Report by Adam Taylor, Professor and Director of the Clinical Anatomy Learning Centre, Lancaster University.
Discovering a relationship between night lighting and vision loss
Scientists at Jeju National University College of Medicine in South Korea have discovered that a high level of nighttime lighting is linked to the acceleration of age-related macular degeneration.
JAMA Network Open indicates that macular degeneration is the main cause of loss of vision in older people.
According to the magazine, researchers analyzed data from more than 126,000 Korean citizens aged 50 and over, and discovered that about 4,100 of them were diagnosed with macular degeneration. They then compared the lighting of these people's residences with satellite images that show the level of illumination at night.
It turned out that elderly people residing in city neighborhoods with high artificial night lighting in open areas were 2.17 more likely to suffer from macular degeneration compared to residents of neighborhoods with low night lighting. Compared to neighborhoods where the level of night lighting is very low, this risk rises to 12 percent.
According to the researchers, additional factors - obesity, smoking and alcohol intake - have been shown to strengthen the relationship between outdoor lighting at night and age-related macular degeneration.
Researchers recommend that patients suffering from this disease quit smoking, eat a balanced diet of fruits, vegetables and foods rich in antioxidants, and wear sunglasses wherever possible.