NEW YORK • That morning cup of coffee may be linked to a lower risk of dying, researchers from a study published in the Annals of Internal Medicine last month concluded.

Those who drank 11/2 to 31/2 cups of coffee a day, even with one teaspoon of sugar, were up to 30 per cent less likely to die during the study period than those who did not drink coffee.

Those who drank unsweetened coffee were 16 to 21 per cent less likely to die during the study period, with those drinking about three cups a day having the lowest risk of death when compared with non-coffee drinkers.

Researchers analysed coffee consumption data collected from the UK Biobank, a large medical database with health information from people across Britain.

They looked at demographic, lifestyle and dietary information collected from more than 170,000 people between the ages of 37 and 73 over a median follow-up period of seven years.

The mortality risk remained lower for people who drank both decaffeinated and caffeinated coffee. The data was inconclusive for those who drank coffee with artificial sweeteners.

"It's huge," said Dr Christina Wee, an associate professor of medicine at Harvard Medical School and a deputy editor of the scientific journal in which the study was published. "There are very few things that reduce your mortality by 30 per cent."

Dr Wee edited the study and published a corresponding editorial in the same journal.

There are, however, major caveats to interpreting this research, she added.

This is an observational study, which means the data cannot conclusively prove that coffee itself lowers the risk of dying; there may be other lifestyle factors contributing to that lower mortality risk among people who drink coffee, such as a healthy diet or a consistent exercise routine.

The average amount of added sugar a cup of sweetened coffee in the study was a little more than one teaspoon - far less than what is typically added to many sugary drinks at coffee chains.

A tall Caramel Macchiato at Starbucks, for instance, contains 25g of sugar, about five times as much sugar as a sweetened cup of coffee from the study.

"All bets are off when it comes to matching this with a latte, a Frappuccino, the supermocha whipped whatever," said Dr Eric Goldberg, a clinical associate professor of medicine at the NYU Grossman School of Medicine.

These beverages tend to be high in calories and fat, he said, potentially negating or at least blunting any benefit from the coffee.

This new study is the latest in a robust line of research showing coffee's potential health advantages, he said.

Previous research has linked coffee consumption with a lower risk of Parkinson's disease, heart disease, Type 2 diabetes, liver and prostate cancers and other health issues.

Scientists do not know exactly what makes coffee so beneficial, Dr Goldberg said, but the answer may lie in its antioxidant properties, which can prevent or delay cell damage.

Coffee beans contain high amounts of antioxidants, which can help break down free radicals that cause damage to cells, said Ms Beth Czerwony, a registered dietitian at the Cleveland Clinic's Centre for Human Nutrition.

Over time, a build-up of free radicals can increase inflammation in the body, which can cause plaque formation related to heart disease, she added, so dietitians recommend consuming foods and beverages that are rich in antioxidants.

There is also the possibility that coffee drinkers tend to make healthier choices in general.

They might opt for a cold brew or a cup of drip coffee instead of a less healthy source of caffeine, such as an energy drink or soda, Dr Goldberg said.

"If you're pounding Mountain Dew, Coca-Cola, Red Bull or all these other drinks, they have tonnes more sugar, all the artificial stuff - versus coffee, which is a generally unprocessed food."

Despite the encouraging evidence about coffee, there is not enough data to suggest that people who do not drink coffee should add a stop to Starbucks during their morning routines, Dr Wee said. And even avid coffee drinkers should not use the study to justify endless cups of java.

The study showed that the benefits of coffee tapered off for people who drank more than 41/2 cups of coffee each day.

Past studies have shown that consuming "extreme amounts" - over seven cups per day - can take a toll, she said.

"Moderation is good," Dr Goldberg said. "But too much of a good thing isn't necessarily more of a good thing."

NYTIMES