You knew it all along. Or wanted to.

Now, we have grounds for a firm belief that coffee is not only good for you. It prolongs your life.

Even if you down eight cups a day. It’s a habit. It tastes good. And it helps your heath. What’s not to like?

So, go ahead, have some more. In larger mugs. All day.

You probably thought Brits drink tea. They do. But also coffee. And a study of the coffee consumption by nearly a half-million of them found that coffee drinkers were less likely to die over a 10-year period. And that applies to all kinds of coffee–ground, instant, even lead-free decaffeinated.

During a decade of follow-up, those coffee drinkers were 10 to 15 percent less likely to croak. No matter how much caffeine they consumed.

It’s not clear exactly why coffee prolonged those lives. Erikka Loftfield, a researcher at the U.S. National Cancer Institute and the study’s lead author, pointed out that coffee has more than 1,000 different chemical compounds such as  antioxidants that help protect cells from damage.

Researchers had study subjects  complete questionnaires on their daily coffee consumption, physical exercise and other personal habits, and they took physical exams including blood tests.

Most participants were coffee drinkers. Almost one-third of them drank two to three cups of coffee daily and 10,000 drank at least eight cups a day.

Coffee did not help everyone. Over the next 10 years, 14,225 participants died, most of them from heart disease or cancer.

As previous studies found, coffee drinkers were indeed more likely than non-coffee-holics to consume alcohol and smoke. However, researchers took those factors into account, and coffee drinking seemed to cancel them out.

The study did not cover whether coffee drinkers took sugar and cream. But previous studies have shown that extra calories and fat are not good.