Coffee aficionados may have strong opinions about dark versus light roast when it comes to flavor — and the debate continues when it comes to their health benefits.
Lighter roasts tend to preserve more of the unique qualities of
coffee than darker roasts, which produce beans that are black and shiny and more bitter because the longer roasting times.
But the impact this has on your health is likely to be minimal at best.
“I often advise clients to base their choice of coffee on taste preference,” says Lyndsay Hall, RD, a registered dietitian at JM Nutrition in Mississauga, Ontario. “Although there may be marginal differences in the health-promoting properties of light versus dark roast coffee beans, these differences are not really significant enough to warrant choosing one over the other.”
The Case for Dark Roast
Dark roast doesn’t just lend a more broody, smoky flavor to your coffee cup — it can also potentially prevent stomach distress and exposure to a potentially harmful chemical. But these perks may not have a noticeable effect on all (or many) drinkers.
Easier on Sensitive Stomachs
“Darker roasts of coffee have been studied to contain less-acidic compounds, so someone with acid reflux may be less likely to react to dark roasts in contrast to light roasts,” Hall says.
The longer roasting process breaks down more acids in the beans, though darker roasts still contain some acid.
“However, the risk of reflux would not be completely eliminated by choosing dark roast coffee,” Hall adds. Other factors like
caffeine content, large quantities, and whether it's piping hot when you drink it can also contribute to reflux symptoms.
To
reduce acid reflux from your coffee, opt for darker roasts, espressos (typically made with darker roasts), or cold brew coffee (where the process and the temperature help to reduce acids).
Lower in Acrylamide
Acrylamide is a chemical that naturally forms early on in the roasting process, but breaks down as roasting continues. It’s also found in food cooked at high temperatures. High levels of acrylamide have been linked to cancer in animals, but the human evidence is not conclusive. Still, health organizations recommend reducing your intake as a precaution when possible.
According to one study, light roast coffee has the most acrylamide, with 0.41 milligrams (mg) in every 100 grams (g). Medium roast had the lowest amounts, at 0.31 mg per 100 g.
“For the amounts in a cup of coffee, the acrylamide levels are within the range of what you’d expect of any commonly roasted food, such as french fries and chips,” says Bryan Quoc Le, PhD, a food scientist, lecturer of sustainable culinary practices at Unity Environmental University, and the founder of Mendocino Food Consulting in Mendocino, California. “It's not expected to be harmful to the average consumer.”
The Case for Light Roast
Similar to dark roast, light roast has some perks (and a brighter flavor). But the benefits tend to be slight.
Higher Antioxidant Levels
While both types of roasts contain
antioxidants, lightly roasted coffee beans retain higher levels of certain types, such as caffeoylquinic acids and feruloylquinic acids, than dark roasted coffee beans. That’s because some antioxidants are highly heat-sensitive and are degraded during the longer roasting process for dark roasts.
“Chlorogenic acid is one antioxidant and anti-inflammatory compound that gets almost entirely removed throughout the dark roasting process,” Hall says, adding that this compound has been linked to
improved metabolic health, including
insulin resistance. Research shows that light roast can have roughly 10-fold the amount of chlorogenic acid as dark roast.
But human research on the effects of chlorogenic acid on metabolic health has used much larger doses than what would be found in coffee, so the true effects of this difference aren’t clear.
May Support Weight Loss
One small study of 38 participants with
obesity or who were overweight found that lightly roasted coffee and regular roasted coffee both led to reduced fat mass and body fat percentage. This reduction was slightly higher with light roasted coffee (1.4 percent) compared with regular roasted coffee (1 percent).
This research is preliminary, though, and larger studies are needed to confirm these findings.
Which Has More Caffeine?
While some caffeine evaporates during roasting, the difference in caffeine content between roast levels is relatively minor — and these differences depend on brewing methods and measuring methods (volume versus weight, for example). The research has been inconclusive overall to say if one type of roast has more caffeine than another.
Short answer: Roasting may affect the total amount of caffeine slightly, but unless you have a caffeine sensitivity, the differences are probably not enough for you to change your coffee order — at least until more research is available.
The Health Impact of Add-Ins
Of course, what you put into your coffee can matter even more for your health than the roast.
“Adding syrups, sugars, or creams does have the potential to negate some of the antioxidant and anti-inflammatory properties of coffee,” Hall says.
“Adding spices like cinnamon, cardamom, or cocoa powder to your coffee grinds before brewing is a great way to add flavor without any sugar or saturated fats,” Hall says. “These spices also contain high amounts of antioxidants on their own, which may further boost the antioxidant effects of coffee.” For example, research has suggested that cinnamon’s antioxidants may help lower cholesterol and lower blood sugar levels in people who have type 2 diabetes.
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Dr. Amara Okafor