The effects of caffeine on the heart, and the body as a whole, are myriad, and the jury is out when it comes to determining if caffeine is dangerous for heart conditions. Studies on caffeine and the heart seem to suggest that low doses, as seen in a couple of cups of coffee or tea, are fine, while high doses can be dangerous for people with cardiovascular problems. Caffeine certainly elevates heart rate and blood pressure, and this can be dangerous for some patients.
When people consume caffeine, the drug acts as a vasoconstrictor, narrowing the blood vessels. This is one reason why people are sometimes advised to take caffeine for a headache, as it can reduce the flow of blood to the head and make the patient feel more comfortable. Narrowing the blood vessels also raises blood pressure, as the blood has to pump harder and build up more pressure to get the blood circulating. This effect of caffeine on the heart can have deleterious effects for people who already have high blood pressure or unstable hearts.
Indirectly, the effects of caffeine on the heart can also be seen in its diuretic properties. People who drink caffeine experience an increased need to urinate and can become dehydrated if they do not get enough fluids. Dehydration can cause changes in blood pressure and can also damage the heart, along with other organs. While people need to drink substantial amounts of caffeine for this to be a risk, it is something to consider.
Some studies have raised concerns about caffeine and cholesterol, noting that high cholesterol levels can result in heart disease. Additional research has suggested that caffeine does not have an impact on cholesterol levels, making it safe for people to consume if they already have high cholesterol. The other effects of caffeine on the heart may be a concern in people with high cholesterol, however, as the compound can contribute to cardiovascular problems by elevating blood pressure.
High caffeine consumption is often associated with stress, which can be dangerous for the heart. Some researchers believe that drinking lots of caffeine can increase stress by making people jumpy or jittery and splitting focus, and this could contribute to cardiovascular problems. People concerned about the effects of caffeine on the heart who don't want to cut out caffeine altogether could switch to drinks with lower levels of compound, and could consume fewer caffeinated beverages. Cutting out caffeine altogether does not appear to have any benefits.
