Kenneth Glad
The effects of a daily caffeine habit depend on dose, preparation and individual sensitivity. Researchers also warn that five cups do not always contain the same amount.
Most adults can safely consume up to 400 milligrams of caffeine a day, according to a scientific statement from the American Heart Association.
That is often described as roughly three to five standard cups of brewed coffee. In practice, the amount can vary widely because cup size, brewing method and added espresso shots all affect caffeine levels.
The statement found that moderate coffee consumption was not linked to a higher risk of cardiovascular disease in most adults. Some of the research reviewed also associated regular intake with lower rates of coronary artery disease, stroke and heart failure.
The evidence applies mainly to coffee. Researchers said less is known about concentrated caffeine from energy drinks and similar products, especially when large doses are consumed quickly.
The US Food and Drug Administration estimates that a typical eight-ounce cup of brewed coffee contains about 95 milligrams of caffeine. A large cafe drink may contain far more, meaning a simple cup count can be misleading.
The findings are broadly reassuring
Studies included in the review linked moderate coffee intake with lower overall mortality, with the strongest association often seen among people drinking about two to four cups per day.
Researchers also found links between habitual coffee consumption and a lower incidence of type 2 diabetes in some groups. These findings come largely from observational studies, so they do not prove that coffee prevents disease.
Gregory M. Marcus, a professor of medicine at the University of California, San Francisco, and a co-author of the statement, said plain coffee appears safe within the general daily limit.
“The equivalent of up to five cups of caffeinated coffee per day without added sugars or fillers is safe and does not increase cardiovascular risk,” Marcus said, according to Euronews.
The review does not suggest that people should start drinking coffee for health reasons. It also does not set a strict universal ceiling, since the effects of caffeine differ from person to person.
Caffeine is processed mainly by the liver and usually reaches peak blood concentration within about an hour. Age, genetics, medication use, metabolism and previous caffeine intake can all influence the response.
Preparation and sensitivity count
Regular coffee drinkers may develop some tolerance, while others can experience palpitations, anxiety or sleep problems after a much smaller amount.
Brewing method may also matter. The American Heart Association statement noted that unfiltered coffee can raise low-density lipoprotein cholesterol, commonly known as LDL cholesterol.
What goes into the cup is important as well. Large amounts of sugar, flavoured syrup, cream or sweetened milk can add substantial calories and reduce the value of choosing coffee as a relatively simple drink.
The 400-milligram figure is best treated as a general guide for most healthy adults. For someone who develops a racing heart or loses sleep after one strong cup, the more useful limit may be much lower.
Sources: American Heart Association; US Food and Drug Administration; Euronews
