Light Roast vs. Dark Roast Coffee: What Type Is Healthiest?

Coffee fanatics know that their beverage offers long-term health benefits related to chronic inflammation, cardiovascular diseases, chronic liver diseases, diabetes, and cancer. But to maximize your health benefits in every cup, should you opt for a light, medium, or dark roast?

"People drink coffee for flavor, caffeine, and many other reasons. And many people won't even want to start their day without it," the late Sampath Parthasarathy, PhD, former associate dean for research at the University of Central Florida, previously told Health. "Most people don't consider antioxidants or anti-inflammatory properties." 

In fact, different coffee roasts may have different levels of antioxidants, anti-inflammatory properties, and acidity. Here's what you need to know about what type of coffee roast is best for maximizing its health benefits.

How Does Roasting Affect Coffee's Health Benefits?

Understanding the difference between coffee roasts is essential to understanding if one roast offers more health benefits.

Roasting is a heat process that brings out the aroma and flavor locked inside the naturally green coffee beans. Roasting causes chemical changes as the beans are rapidly brought to very high temperatures. If you end up with a light, medium, or dark roast depends on the time and temperature of roasting. Higher temperatures and longer roasting times result in darker roasts.

As the beans are being roasted, the temperature changes the compounds that make up the beans. That chemical change affects the coffee's smell, taste, and antioxidant properties.

Organic compounds, or super antioxidants, are found abundantly in plants. One group of compounds affected during roasting is polyphenols. Some research suggests that consuming polyphenols may play a vital role in health by regulating metabolism and weight, preventing chronic diseases, and improving cell production. 

Because people have different preferences for different types of roast based on taste and smell qualities, experts have tried to understand what is best for our health.

How Coffee Roasts Affects Antioxidants

Light roasts may have an advantage when it comes to the number of polyphenols, a type of antioxidant, remaining after the roasting process. Some studies suggest that the longer that coffee beans are roasted, the less polyphenol they will have. 

But antioxidant activity significantly rises with the degree of roasting. For example, strongly roasted coffee has higher antioxidant activity than lightly roasted coffee. And those antioxidants may compensate for the lack of polyphenols in dark roasts. So, while light roast contains more polyphenols, dark roast may have more antioxidants.

Additionally, the region where coffee beans are cultivated is a significant factor in the number of antioxidants. Research has found that Arabic coffee, cultivated in Tanzania, Ethiopia, and Brazil, has the highest total antioxidant content.

Researchers also examined antioxidant levels in a study published in the Journal of Medicinal Food in 2017. The researchers compared coffees of several different roasting levels. They analyzed their caffeine content and levels of chlorogenic acid, an antioxidant. The researchers also exposed extracts of each coffee to human cell cultures to test their antioxidant and anti-inflammatory properties.

The researchers found that the lighter the roast, the higher the chlorogenic acid content—and the better the coffee extract protects human cells against cell damage.

Other research has found that antioxidant activity reaches a maximum level with light roasts. Then, antioxidant activity decreases as the heating process creates dark roasts.

But acrylamide levels increase as antioxidant levels reach a maximum in light roasts.  Acrylamide is a substance that forms during high-temperature cooking—like frying, roasting, and baking. Some evidence suggests that high levels of acrylamide cause cancer in laboratory animals.

What Type of Coffee Roast Has the Most Anti-Inflammatory Properties?

Research has found that light roasts have more substantial anti-inflammatory effects than dark roasts. But it's important to note that researchers conducted the study on cell cultures, not humans. Dr. Parthasarathy explained that researchers would need to replicate those results in human trials.

"We know that antioxidants protect against many health problems. And we also know that inflammation is the basis of many chronic diseases, whether it is diabetes, heart disease, cancer, or neurological diseases like Alzheimer's," explained Dr. Parthasarathy. "But these diseases are progressive and occur over a long period of time. And you can't see long-term benefits in a test-tube study."

But antioxidants aren't always anti-inflammatory (and anti-inflammatory compounds aren't always antioxidants). Still, Dr. Parthasarathy said the two often go hand-in-hand.

What Coffee Roast Is Less Acidic?

Some coffee lovers drink decaf or forgo the beverage altogether. Sometimes, coffee irritates the stomach or brings on heartburn caused by gastric acid secretion. 

Researchers have also compared roasts based on acidity. Some evidence suggests that darker roasts lead to less gastric acid secretion than medium roasts. Therefore, dark roast may be easier on the stomach than other roasts.

A Quick Review

Coffee offers a multitude of health benefits to help prevent chronic illness. The type of roast you prefer will likely depend on taste and smell preferences. Though, there are differences in the antioxidant, anti-inflammatory, and acid content.

Dr. Parthasarathy noted that you're likely getting some benefits if you love dark roasts for their flavor. But cup for cup, light roasts may have more powerful effects.

"If both types have the same amount of caffeine, why would you compromise on the antioxidant and anti-inflammatory effect?" said Dr. Parthasarathy. "People might have to ask themselves, to what extent is the aroma important to them? Are they drinking coffee for health, or just to feel good?"

Future research might help coffee producers focus on the type of coffee and level of roasting that maximizes health. For example, companies like Starbucks tout their dark French roast for its rich flavor, "but it may not be better for health benefits," according to Dr. Parthasarathy.

Of course, how long coffee is roasted is only part of maximizing its superfood potential. Different types of beans grown in other regions and climates may impact the coffee's health benefits. And different brewing processes, like cold brew, also play a role.