Most of us rely on a cup of coffee to jumpstart our morning, and an espresso shot to get us through the mid-afternoon slump. Seriously, 54 percent of American adults drink about 3 cups a day. But with all that caffeine, some people may end up feeling guilty or anxious about their health. Just how much does caffeine affect the body? In Brit Lab’s video above, host Michael Mosley explains that although caffeine might not be great for us, the other components in coffee provide a wealth of health benefits, including reducing heart disease and dementia risk.

In the United States, 75 percent of caffeine consumption is coffee, amounting to 40 million cups of coffee per day. The new 2015 dietary guidelines released by the Advisory Committee say 3 to 5 cups of coffee are OK as long as there’s no cream, milk, or sugar added. However, the amount of coffee each person can tolerate is dependent on factors like age, weight, genetics, and how much caffeine they had consumed recently.

In the brain, caffeine blocks the chemical adenosine from latching on to its receptors, and inducing drowsiness — by way of slowing down nerve cell activity. This binding also causes blood vessels to dilate, allowing more oxygen to pass through the body during sleep. Caffeine, however, takes adenosine’s place in these receptors and intercepts its message, causing alterness.

It also constricts the blood vessels and increases our levels of adrenaline, making our blood pressure and heart rate go up. While this isn’t anything to worry about for most people, some coffee drinkers might be susceptible to the overstimulation, and experience abnormal heart rhythms and high blood pressure.

In the grander scheme of things, coffee is one of the healthiest caffeine-based options we have. Whether you get it caffeinated or decaffeinated, both will be rich in polyphenols — micronutrients associated with a reduced risk of heart disease, dementia, and stroke. Moreover, studies have found coffee drinkers who consume 3 to 4 cups a day live longer than those who don’t.