Caffeine is a naturally occurring substance that can be found in cocoa beans and tea leaves. It can be found in the majority of our popular beverages today, and over 90 percent of the world consumes caffeine in one form or another each year. Caffeine directly affects the central nervous system and can lead to major physical affects such as an increased heart rate, higher metabolism and an increase in restlessness. Caffeine hasn't been linked to any major health problems, but because of its addictive quality it is advised that you limit your caffeine consumption to a few 100 mg a day.
Caffeine Increases Heart Rate
By interacting with your central nervous system caffeine can noticeably affect your heart rate. A higher level of caffeine leads to a higher heart rate which is why very high levels of caffeine can be dangerous. Although moderate levels of caffeine consumption like drinking a few cups of coffee aren't going to cause a significant rise in your heart beat, very high doses found in energy pills or drinks can cause more dangerous effects such as a heart rate increase to the point of palpitations, or severe headaches and dehydration.
Caffeine Increases Release of Epinephrine
Caffeine is known to increase the amount of epinephrine that your body's adrenal gland releases. Epinephrine is the chemical that creates the "flight or fight" feeling and the effect of an increase in the chemical is an increase in heart rate, constriction of blood vessels and increased mobilization of sugar and fat for higher levels of energy.
Caffeine Inhibits Adenosine Functions
One of the main ways that caffeine is able to speed up your heart rate is by making adenosine less effective at calming the nervous system down. Adenosine is a nucleotide produced in the brain. It plays an important role in relaxation and promotes sleep. Caffeine is so similar to adenosine that it is able to attach to the receptors that adenosine usually attaches to. By attaching to the receptors, adenosine has nowhere left to go and cannot do its job. After the caffeine has attached to the receptors it speeds up the nervous system even more making its effects even more noticeable.
Caffeine Amounts in Everyday Consumables
The average amount of caffeine a US resident drinks daily is 200 mg, or two 8 oz. cups of coffee. Here is a breakdown of the amount of caffeine in many of the popular drinks and food that many of us consume on a daily basis. Brewed coffee has between 65 and 120 mg of caffeine per 8 oz. serving. Instant coffee has a little less at between 60 and 85. In the same size serving, chocolate milk has 2 to 7 mg of caffeine, green tea has 30 mg to 50 mg, and black tea has 30 to 60 mg of caffeine. A tiny 2 oz. shot of espresso has an amount of caffeine very similar to coffee at 60 to 100 mg and cappuccino beverages have the same amount of caffeine as espresso. A single ounce of dark chocolate has between 5 and 35 mg of caffeine and most surprising of all decaf coffee has between 2 and 4 mg of caffeine per 8 oz.
Member Comments