An exception is for Parkinson’s disease, which seems to be primarily affected by the caffeine. In most cases, decaf coffee should have the same beneficial effects. Yet, these results are worth bearing in mind. Thus, aiming for 4–5 cups of coffee per day seems optimal.Īs all of these studies were observational in nature, they cannot prove that coffee caused the reduction in disease - only that coffee drinkers were less likely to get these illnesses. Studies have shown that 4 cups or more of coffee per day are linked to a 20% lower risk of depression and a 53% lower risk of suicide ( 21, 22). Coffee is associated with a reduced risk of Parkinson’s, with the greatest reduction seen at 5 cups or more per day ( 20). In one study, 3–5 cups per day were linked to a 65% decreased risk of Alzheimer’s disease ( 19). Your risk of liver cancer is reduced by 44% for every 2 cups daily ( 18). Drinking 4 cups or more of coffee daily brings the greatest reduction - up to 84% - in liver cirrhosis, a severe consequence of some liver diseases ( 16, 17). One study found a 7% decrease for each daily cup ( 15). The more coffee people drink, the lower their risk of type 2 diabetes. SUMMARYĪlthough the evidence isn’t settled, several studies suggest that coffee drinkers live longer - with the optimal amount of coffee being around 4–5 cups per day.Ĭoffee has also been linked to a reduced risk of various illnesses, including: Nonetheless, variations in volume between differently sized coffee cups are generally not very great. Note that these and most other studies don’t specify whether “cup” refers to a standard 8-ounce (240-ml) cup or just a generic vessel that people may use to drink coffee, independent of volume. One recent study found that drinking 4 cups or more per day was linked to an increased - not decreased - risk of death in people under age 55 ( 14). Two other reviews backed similar results ( 12, 13). In one study in 402,260 people ages 50–71, those who drank 4–5 cups of coffee per day had the lowest risk of death over the 12–13-year study period ( 11). It has even been linked to increased longevity. While high caffeine intake causes adverse side effects, coffee is associated with many health benefits. Sensitivity to caffeine is highly variable and depends on genes and receptors for caffeine in your brain. If you want to know more about your tolerance, speak to your medical provider. If you have anxiety, panic disorder, heart arrhythmia, high blood pressure, diabetes, or other medical conditions, you may tolerate less caffeine. It’s also important to realize that medical conditions can affect sensitivity to caffeine. Those who drink coffee every day can tolerate much more than those who drink it rarely. Your acquired tolerance is also very important. Some people can drink coffee and go to sleep immediately, while others are kept awake throughout the night.ĭepending on your genetic makeup, you may tolerate a lot of caffeine - or very little. The effects of caffeine on sleep are also genetically determined.
These genes affect the enzymes that break down caffeine in your liver, as well as receptors in your brain that are affected by caffeine. Many genes have been discovered that affect people’s sensitivity to this stimulant ( 9, 10). Many sources recommend 400 mg of caffeine per day as the safe upper limit for healthy adults.Ĭaffeine affects people in different ways.
The caffeine content of your morning joe can range from 50 to over 400 mg. Keep in mind that many other sources of caffeine exist, including tea, soft drinks, energy drinks, chocolate, and certain medications ( 6, 7). However, many people drink much more than that without any issues. Several sources suggest that 400 mg of caffeine per day - the equivalent of 4 cups (945 ml) of coffee - is safe for most healthy adults ( 3, 5). Caffeine, an active ingredient in coffee, is the most commonly consumed psychoactive substance in the world ( 4).Ĭoffee’s caffeine content is highly variable, ranging from 50 to over 400 mg per cup.Ī small home-brewed cup of coffee could provide 50 mg, while a 16-ounce (475-ml) Starbucks grande packs over 300 mg.Īs a general rule, you can assume that an average 8-ounce (240-ml) cup of coffee offers around 100 mg of caffeine.