There’s no shortage of scientific research suggesting that drinking coffee can help you live a longer, healthier life. Multiple high-quality studies—including a landmark 2018 report that analyzed more than half a million people over the course of a decade—have found moderate coffee consumption to offer protective, lifespan-extending benefits for both brain and body. “For most people, it’s the richest source of bioactive compounds, like antioxidants, polyphenols, and phytochemicals,” says Dr. Andrew Odegaard, associate professor of epidemiology and biostatistics at UC Irvine Joe C. Wen School of Population and Public Health.

But how much coffee do you actually need to drink in order to optimize your healthspan and potentially add years to your life? Do things like preparation, type, and timing factor in? And what about decaf? For the answers to these questions and more, we consulted the experts. Here’s everything you need to know the next time you square up to the barista at your local cafe.

Caffeinated is a little better than decaf

There’s a ton of research linking regular caffeine consumption to a reduced risk of neurodegenerative disorders like Alzheimer’s disease, dementia, and Parkinson’s disease. It’s also been associated with reduced cognitive decline, increased motor speed, and improved memory. But what’s worth pointing out is that in virtually all of these studies, caffeine was administered in the form of coffee—and there’s more to coffee than just caffeine. In fact, caffeine isn’t the only active ingredient in coffee, and when it comes to longevity, it may not even be the most important.

“Caffeine does not seem to be the most likely contributor to these observed effects,” says Dr. Farhan Abdullah, board-certified internist, adjunct clinical assistant professor at UT Southwestern, and medical director of Magnolia Functional Wellness in Southlake, TX. A study published in the journal JAMA Internal Medicine found that the longevity benefits of coffee consumption were consistent even among subjects who were unable to efficiently metabolize caffeine. “It was actually a really interesting study,” Dr. Abdullah says, “because we always thought it was caffeine causing the improvements in lifespan—and we found it wasn’t caffeine doing all the heavy lifting.”

Experts believe that the primary source of coffee’s longevity benefits is more likely the plant-based antioxidants, or polyphenols, that it contains, including chlorogenic acid, ferulic acid, and p-Coumaric acid—all of which are also present in decaf coffee. “The chlorogenic acid is actually the MVP,” Abdullah says. “It’s the thing that’s helping to decrease oxidative stress. It’s helping to keep blood vessels viable. And it’s also improving insulin sensitivity. The caffeine ends up being almost like a bonus.”

Light and dark roasts offer comparable benefits

The process of roasting coffee degrades some of its chlorogenic acid, but that’s not necessarily a reason to avoid a darker roast if that’s your preference. High heat doesn’t simply destroy these valuable polyphenols; rather, it converts them, along with sugars and amino acids contained in coffee, into polymers called melanoidins, which can be just as valuable. Research, including a 2012 paper published in the journal Food & Function, has found that melanoidins can help protect the body against oxidative stress, inflammation, hypertension, cellular damage, and even cancer. “As the chlorogenic acid decreases, these melanoidins increase, and you still end up with a beneficial effect,” Abdullah says.

Since all coffee undergoes some degree of roasting, fans of lighter roasts needn’t worry about missing out on melanoidins. Similarly, a darker roast won’t totally eradicate chlorogenic acid from your brew. (And don’t worry, ordering either option iced will deliver all the same benefits—we asked.) Rather, Abdullah encourages people to think of it as a spectrum: you can skew slightly in one direction or the other, but either way, you’re likely benefiting from a little bit of everything. “It’s not so much one versus the other,” he says. “It’s not just the chlorogenic acid. It’s not just the caffeine. It’s not just the melanoids. It’s a combination.”