How Cold Brew Compares To Hot Coffee & Why It Might Give You Jitters

Switching from hot coffee to cold brew is a seasonal rite that many look forward to once summer hits. The smooth, rich beverage goes down easy on hot days. But how does cold brew coffee compare to its hot counterpart in terms of health benefits?

Cold brew is made by immersing coffee grounds in cold water (immersion method) or slowly dripping cold water over grounds (drip method). Both of these processes take significantly more time than hot coffee preparations. The drip method can require at least five hours, while the immersion method can take up to an entire day.

However, the longer you brew your coffee, the stronger it will be. This is why the data on exactly how much caffeine is in a typical cup of cold brew is inconsistent1. With such variation in brew times, cold brew's caffeine content can actually end up equal to, if not higher than, hot coffee.

"The temperature also contributes to flavor differences," Cornelis adds. Cold brew coffee tends to be less acidic, less bitter, and more sweet. This is because the different sugars, oils, and aromatic compounds in coffee oxidize at different rates. Sugars take longer to break down than acids. So the longer brew time of cold brew leads to a higher ratio of natural sugar to acids, leading to a stronger, sweeter cup.

Feel jittery after drinking cold brew, or notice your anxiety spike? This could be a sign you're gulping down your brew too quickly or that you're sensitive to its caffeine content.

Cornelis has done some fascinating work on the genetics of coffee consumption, and it turns out that one gene (CYP1A2) is responsible for 95% of caffeine metabolism2. "Individuals with a particular variant of this gene consume more coffee while others who have the other variant consume less," she explains.

Interestingly enough, people with the gene variant that allows them to drink more caffeine also seem to have lower caffeine levels in their blood than those who don't have the variation. "This would suggest that these individuals, despite consuming a lot of caffeine, are metabolizing it very quickly. So they need to consume more," she says. "There seem to be some genetic underpinnings to the differences we see with caffeine consumption."

If you fall into the slower caffeine metabolizer camp, you can tone down the intensity of your cold brew by drinking coffee that has a shorter brew time or has been diluted with some water.

If you can drink cold brew all day without any side effects, you may be the lucky owner of a fast-metabolizing CYP1A2 gene. Go forth and sip on—there's overwhelming evidence to show that drinking coffee is a healthy habit.

In one cohort study on nearly 500,000 adults3 co-authored by Cornelis, drinking coffee (both decaf and caffeinated) was inversely associated with mortality. Participants who drank up to eight cups a day still seemed to reap longevity perks—though the FDA recommends capping your caffeine intake at 400 milligrams4 a day, or about four to five cups of coffee.