Is Dark Roast Coffee Healthier than Medium or Light Roast?

By Adin Smith, MS | Posted July 31, 2021

New research suggests that dark roast coffee is a healthier choice over medium or light roast coffee.[1]Kolb H, Kempf K, et al. Health Effects of Coffee: Mechanism Unraveled? Nutrients. 2020 Jun 20;12(6):1842.

It turns out that the coffee roasting process results in higher concentrations of unique health-promoting compounds.

But before you decide on drinking one roast over another, let’s review the differences in health benefits between dark roast and light roast coffee.

Differences in Health Benefits

Dark roast coffee appears to boost antioxidant levels—specifically vitamin E and glutathione.

For a brief review, glutathione is considered a master antioxidant involved in recycling vitamins E and C, tissue reparation, and immune health. Vitamin E is a powerful antioxidant, playing an essential role in proper immune cell functioning and cell membrane health throughout the body. 

One study compared the effects of light roast vs. dark roast coffee on blood levels of vitamin E and glutathione among healthy volunteers.[2]Kotyczka C, Boettler U, et al. Dark roast coffee is more effective than light roast coffee. Mol Nutr Food Res. 2011 Oct;55 (10):1582-6.

Participants consumed two cups of dark roast coffee per day for a month, then switched over to drinking light roast coffee for another month. The researchers noted that dark roast coffee consumption was more effective at increasing blood levels of antioxidants vitamin E and glutathione at trial end. Additionally, dark roast coffee was better at promoting weight loss among individuals carrying excess weight.

These findings suggest that dark roast coffee may help the body increase its antioxidant levels in a manner that helps protect against DNA damage.

For DNA Protection, Go Dark

Our cells have protective systems to help guard against various toxins that may cause harm.[3]Ma Q. Role of nrf2 in oxidative stress and toxicity. Annu Rev Pharmacol Toxicol. 2013;53:401-426. However, not all types of toxins are harmful, as we need some amounts to function optimally.[4]Finkel T. Signal transduction by reactive oxygen species. J Cell Biol. 2011;194(1):7-15. Many plant compounds, including those found in coffee, are “helpful toxins” that create mild cellular stress that activates protective systems within our cells.[5]Qin S, Hou DX. Multiple regulations of Keap1/Nrf2 system by dietary phytochemicals. Mol Nutr Food Res. 2016 Aug;60(8):1731-55. Regular activation of these systems may provide wide-reaching health effects, limiting DNA damage and increasing antioxidant levels.[6]Hochkogler C, Schweiger K. Daily consumption of a dark-roast coffee for eight weeks improved plasma oxidized LDL and alpha-tocopherol status. J Funct Foods. 2019 May;56:40-48. ,[7]Bakuradze T, Boehm N, et al. Antioxidant-rich coffee reduces DNA damage, elevates glutathione status and contributes to weight control. Mol Nutr Food Res. 2011 May;55(5):793-7. 

Each cell in the body incurs at least ten thousand DNA-damaging events per day.[8]Ames BN, Shigenaga MK, et al. Oxidants, antioxidants, and the degenerative diseases of aging. Proc Natl Acad Sci U S A. 1993 Sep 1;90(17):7915-22. Provided our cells can keep up with their natural repair process—properly fixing each DNA-damaging event— cells can maintain their proper DNA structure. However, excessive DNA-damaging substances caused by environmental toxins (i.e., air pollution) or internal toxins produced from within the body may have unhealthy consequences. Fortunately, evidence suggests that certain compounds found in coffee may help protect against DNA damage.

A four-week study measuring the effects of drinking three cups of dark roast coffee per day vs. a water equivalent on DNA damage found that individuals assigned to the dark roast coffee group had 27% less DNA damage.[9]Bakuradze T, Lang R, et al. Consumption of a dark roast coffee decreases the level of spontaneous DNA strand breaks: a randomized controlled trial. Eur J Nutr. 2015 Feb;54(1):149-56.

A similar four-week study conducted two years later measured the effects of drinking two cups of dark roast coffee vs. a water equivalent on DNA damage.[10]Schipp D, Tulinska, et al. Consumption of a dark roast coffee blend reduces DNA damage in humans: results from a 4-week randomized controlled study. Eur J Nutr 2019 Dec;58(8):3199-3206. Near identical results from this study reported that compared to those drinking water, dark roast coffee drinkers had 23% less DNA damage.

In contrast to dark roast coffee, light roast coffee appears to have a weaker effect on protecting against DNA damage. For instance, one study showed that drinking light roast coffee compared to a water equivalent for five days decreased markers of DNA damage by roughly 12%—which was about half the potency seen in the dark roast coffee studies.[11]Mišík M, Hoelzl C, et al. Impact of paper filtered coffee on oxidative DNA-damage: results of a clinical trial. Mutat Res. 2010 Oct 13;692(1-2):42-8. Furthermore, an eight-week study measuring the effects of drinking 3-5 cups of light roast coffee vs. a water equivalent on DNA damage did not show a significant protective effect.[12]Shaposhnikov S, Hatzold T, et al. Coffee and oxidative stress: a human intervention study. Eur J Nutr. 2018 Mar;57(2):533-544.

Better Antioxidant Defense

Dark roast coffee contains higher amounts of the compounds responsible for activating the body’s antioxidant defense systems. When roasting coffee beans, a compound known as trigonelline gets converted to N-methylpyridinium (NMP), a potent activator of the Nrf2 antioxidant defense system during the roasting process.[13]Boettler U, Volz N, et al. Coffees rich in chlorogenic acid or N-methylpyridinium induce chemopreventive phase II-enzymes via the Nrf2/ARE pathway. Mol Nutr Food Res. 2011 May;55(5):798-802. In contrast, lightly roasted beans have lower amounts of NMP, and may not activate antioxidant defenses as strongly. To make matters worse for light roast, it has higher amounts of trigonelline—a compound that is known to interfere with antioxidant defenses.[14]Boettler U, Sommerfeld K, et al. Coffee constituents as modulators of Nrf2 nuclear translocation and ARE (EpRE)-dependent gene expression. J Nutr Biochem. 2011 May;22(5):426-40.

Conclusion

Compared to light roast coffee, dark roast coffee contains higher amounts of unique coffee compounds that provide potent cell-protective effects. Overall, any coffee roast type appears to offer health benefits, but considering this new research, the benefits of dark roast coffee may be the best choice for optimal health.

References

References
1Kolb H, Kempf K, et al. Health Effects of Coffee: Mechanism Unraveled? Nutrients. 2020 Jun 20;12(6):1842.
2Kotyczka C, Boettler U, et al. Dark roast coffee is more effective than light roast coffee. Mol Nutr Food Res. 2011 Oct;55 (10):1582-6.
3Ma Q. Role of nrf2 in oxidative stress and toxicity. Annu Rev Pharmacol Toxicol. 2013;53:401-426.
4Finkel T. Signal transduction by reactive oxygen species. J Cell Biol. 2011;194(1):7-15.
5Qin S, Hou DX. Multiple regulations of Keap1/Nrf2 system by dietary phytochemicals. Mol Nutr Food Res. 2016 Aug;60(8):1731-55.
6Hochkogler C, Schweiger K. Daily consumption of a dark-roast coffee for eight weeks improved plasma oxidized LDL and alpha-tocopherol status. J Funct Foods. 2019 May;56:40-48.
7Bakuradze T, Boehm N, et al. Antioxidant-rich coffee reduces DNA damage, elevates glutathione status and contributes to weight control. Mol Nutr Food Res. 2011 May;55(5):793-7.
8Ames BN, Shigenaga MK, et al. Oxidants, antioxidants, and the degenerative diseases of aging. Proc Natl Acad Sci U S A. 1993 Sep 1;90(17):7915-22.
9Bakuradze T, Lang R, et al. Consumption of a dark roast coffee decreases the level of spontaneous DNA strand breaks: a randomized controlled trial. Eur J Nutr. 2015 Feb;54(1):149-56.
10Schipp D, Tulinska, et al. Consumption of a dark roast coffee blend reduces DNA damage in humans: results from a 4-week randomized controlled study. Eur J Nutr 2019 Dec;58(8):3199-3206.
11Mišík M, Hoelzl C, et al. Impact of paper filtered coffee on oxidative DNA-damage: results of a clinical trial. Mutat Res. 2010 Oct 13;692(1-2):42-8.
12Shaposhnikov S, Hatzold T, et al. Coffee and oxidative stress: a human intervention study. Eur J Nutr. 2018 Mar;57(2):533-544.
13Boettler U, Volz N, et al. Coffees rich in chlorogenic acid or N-methylpyridinium induce chemopreventive phase II-enzymes via the Nrf2/ARE pathway. Mol Nutr Food Res. 2011 May;55(5):798-802.
14Boettler U, Sommerfeld K, et al. Coffee constituents as modulators of Nrf2 nuclear translocation and ARE (EpRE)-dependent gene expression. J Nutr Biochem. 2011 May;22(5):426-40.

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