Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

For those drinking non-paper-filtered coffee, like boiled, French press, or Turkish coffee, the amount of cholesterol-raising compounds in the lightest roast coffee may be twice as high compared to using very dark roast beans. So, it appears some of the cholesterol-raising compounds are destroyed by roasting. So, in this case darker would be better, or, you can just use a paper filter and eliminate 95 percent of the cholesterol-raising activity of coffee, regardless of the roast, as I’ve described before.

But I did another video showing dark roasting may also destroy up to nearly 90 percent of the chlorogenic acids, which are the antioxidant anti-inflammatory phytonutrients purported to account for many of coffee’s benefits. So, in that case, light roast would be better. On the other hand, dark roasting can wipe out up to 99.8 percent of pesticides in conventionally-grown coffee, and more than 90 percent of a fungal contaminant called ochratoxin, which is a potent kidney toxin found in a wide range of food ingredients that can get moldy.

But then, what about the polycyclic aromatic hydrocarbon products of combustion that are “suspected to be carcinogenic” and DNA-damaging? Darker roasts may have up to four times more than light roasts. Thus, they advocate controlling roasting conditions to cut down on these combustion compounds. Just to put things in perspective, even the darkest roast coffee might only max out at a fraction of a nanogram of benzopyrene per cup—considered to be “the most toxic” of these compounds—whereas a single medium portion of grilled chicken could have over 1,000 times more.

Overall, you don’t know if light versus dark roast is better until you… put it to the test. This study found that “Dark roast coffee is more effective than light roast coffee in reducing body weight…” Folks were randomized to a month of drinking two cups a day of light roast coffee or dark roast coffee, roasted from the same batch of green coffee beans. And in normal weight subjects, it didn’t seem to matter—no significant weight changes either month—but in overweight study subjects, they ended up about six pounds lighter drinking dark roast coffee compared to light roast coffee; more than a pound a week lost just drinking a different type of coffee.

What about light versus dark in relation to blood sugars? We’ve known since 2015 that even a single cup of coffee can affect the blood sugar response. Here’s the blood sugar spike over two hours after drinking a cup of coffee with more than a dozen sugar cubes in it (like a quarter cup of sugar in one cup of coffee), compared to the spike from the same amount of sugar in just plain water. What is not known is whether this increase in blood sugars is actually clinically meaningful. After all, coffee consumption does not seem to increase the risk of diabetes, and if you compare light roast coffee to dark roast coffee right before chugging down about 20 teaspoons of sugar, there didn’t appear to be any difference. Perhaps the take-home message is: light or dark, maybe we shouldn’t be adding 20 spoonfuls of sugar.

And finally, what about the effect of different roasts on heartburn and stomach upset? We’ll find out next.

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