Once a local fetish, the cold-brew coffee trend kicked off in earnest in the summer of 2014 and expanded to become an international coffee movement. But questions remain about whether the brew process, which involves soaking coffee grounds in cold or room-temperature water for long periods, benefits consumers beyond the subjective issue of taste.
"As the market has picked up, marketers are beating consumers over the head on all sides with claims about the quality and sometimes unsubstantiated health benefits of RTD cold brew," says Nick Brown, editor of Roast Magazine's Daily Coffee News.
Those health claims include lower caffeine and acidity from a process that simply replaces the heat of a regular brew with time.
So How Does Cold-Brew Coffee Work?
The method creates coffee concentrate by soaking grounds in cold or room-temperature water for 12 to 24 hours. The filtered final product is diluted with two or three parts hot or cold water and milk or dairy substitute to one part coffee. The concentrate, or "essence," can also be stored in the refrigerator for up to six weeks or frozen for a longer period.
Not to be confused with traditional iced coffee, in which hot-brewed coffee is poured over ice, cold-brew coffee is the product of a process that some claim can trace its early history to Dutch traders in the 1600s looking for a way of producing coffee that traveled easily. Others believe the practice began in Japan or Central and South America, according to DailyCoffeeNews.com.
Cold-Brew Coffee’s Health Claims
Coffee made from cold-brew concentrates has been credited with containing less caffeine and less acid than coffee made in the traditional hot-brewing method.
Claim #1: Lower in Caffeine
In tests using Starbucks' regular coffee blend, researchers engaged by cold-brew system maker Toddy found that the cold-brew coffee had 40 milligrams of caffeine per 100 grams, while a store-brewed coffee registered at 61 milligrams of caffeine.
Large amounts of caffeine may lead to osteoporosis or fibrocystic disease, according to the National Institutes of Health. The NIH also warns against too much caffeine for pregnant women and children.
Claim #2: Lower in Acidity
The Toddy study also found that regular coffee brewed cold had a pH of 6.31, as opposed to a 5.48 pH for the hot-brewed version. (On the pH scale lower numbers denote more acid.)
A diet lower in acid is credited with various benefits that would make cold-brewed coffee, if its low-acidity claims are true, appeal to health-conscious consumers. Some of those benefits may include supporting bone health, reducing muscle wasting and lessening the severity or incidence of hypertension and strokes, according to an article in the Journal of Environmental and Public Health called "The Alkaline Diet: Is There Evidence That an Alkaline pH Diet Benefits Health?"
In addition, the report noted, reversing the decrease in growth hormone caused by an acidic diet may benefit everything from cardiovascular health to memory and cognition.
But is that enough evidence to give up your coffeemaker?
"Nearly every hot- and cold-brewing method is different from the next, using different coffees, different ratios, different roasts and different recipes," Brown notes. Plus, cold brew's lower-acidity claims can generally be traced to the study commissioned by Toddy, Brown says, and the difference hasn't been researched enough by the scientific community.
Claim #3: Doesn't Affect Cholesterol
Fitness expert Jillian Michaels recently invested in Lucky Jack Organic Coffee Co., which makes a bottled organic cold-brew coffee infused with nitrogen.
The former coach on NBC's "Biggest Loser" told Forbes.com contributor Robin D. Schatz that cholesterol concerns are one reason she decided to get into the business: "I'm a coffee person. But there are some issues with coffee. For example, coffee is the second-highest sprayed crop in the world. In addition, how you brew your coffee can have an impact your health. Studies have shown us with coffee that's hot-brewed, some individuals can actually raise their LDL levels, which is also bad."
A rise in cholesterol may not be limited to hot-brewed coffee, however. Cafestol and kahweol, chemical compounds known as diterpenes, are a natural part of the oils of the coffee, but they "raise the serum concentration of cholesterol and triglycerides in humans, and they also appear mildly to affect the integrity of liver cells," according to a 1996 paper presented in the Journal of the Royal Society of Medicine.
Filtering coffee removes cafestol and kahweol. Yet since coffee is soluble and cold water doesn't dissolve coffee as well as hot water — which contributes to cold brew's less acidic taste — it's possible that certain compounds don't leach out of the coffee grounds when brewed with cold water.
More study is needed to determine if cold-brewing removes or inhibits the diterpenes, so you may want to also filter your cold-brew essence before consuming it if you have cholesterol concerns.
Heart Disease, Cancer and More
Coffee generally has been shown to be rich in antioxidants that may help prevent aging-related ailments like heart disease, Alzheimer's and cancer. While you might have other reasons to love your cold brew, there is no evidence to suggest that the cold-brew process negates or enhances those antioxidants.
The process of oxidation, according to UCLA's Science and Food, happens at a higher rate when coffee is brewed hot. Oxidized coffee oils can cause coffee to taste bitter and sour, but whether the high temperature also reduces coffee's antioxidant benefits has not yet been fully researched.
Read the Label on Ready-to-Drink Packaged Cold Brews
Ready-to-drink (RTD) products might be shelf-stabilized in ways home-brewed drinks aren't, Brown says. He recommends that consumers scour product labels for ingredients they would normally avoid in any other drink or processed food.
"There's a tremendous and quite confusing variety of RTD products out there, with more coming every day," Brown says. "The cold RTD beverage segment as a whole has been growing strong, and I'm sure cold brew, being produced largely by coffee roasters, has gotten a bump from the kind of American 'craft food' movement."
Market observers credit the rise of RTD products to companies like Portland-based Stumptown, which began selling its packaged cold-brew coffee in 2011.
Other Possible Benefits
The cold-brew method would also seem to save a few pennies on electricity — and the physical process of producing a large jug of cold brew may well burn a few calories. Reuse your coffee grounds in your garden or for a body scrub to make cold-brew an all-around more eco-friendly choice.
What Do YOU Think?
Are you a fan of cold-brew coffee? Why or why not? What are your thoughts on the health claims about this new trend? Tell us in the comments!