With a boost from at-home consumption and gourmet drinks, coffee culture is on the rise globally—and particularly across Asia. In China, for example, coffee increasingly rivals tea in popularity, giving it the potential to transform one of the world’s smallest coffee markets into its largest. There are already twice as many Starbucks in Shanghai as in New York City.
Regardless of where they reside, many coffee drinkers face the same dilemma—how to enjoy the benefits of caffeine while avoiding its downsides. Coffee can help boost your productivity throughout the day, but it can also cause nervousness, muscle tremors and an upset stomach if you consume too much.
Here, to help you better manage your daily dose of java, we answer four key questions about coffee consumption.
1. What should be my daily coffee limit?
How you react to caffeine depends on how much you’re used to consuming. People who don’t regularly drink caffeinated beverages tend to be more sensitive to caffeine’s negative effects. How you tolerate it can also depend on your genetics and lifestyle, as well as health conditions, such as anxiety disorders.
However, while there’s no universal reaction to caffeine, there is a loose medical consensus that up to 400 milligrams a day is safe for most healthy adults. That’s roughly the amount in four cups of brewed coffee, 10 cans of soda or two energy drinks.
2. When’s the best time of day for consumption?
Our bodies produce a hormone called cortisol (i.e., the stress hormone). It is a key component of our natural, daylong hormonal cycle, which helps wake us in the morning and wind us down at night. Cortisol levels normally increase by up to 50% in the 20 to 30 minutes after waking, making us naturally energized.
Consequently, drinking coffee first thing in the morning can be counterproductive to your body’s natural cycle. “If you are drinking caffeine at a time when your cortisol concentration in the blood is at its peak, you probably should not be drinking it,” states Steven Miller, a Ph.D. candidate at the Uniformed Services University of the Health Sciences in Bethesda, Maryland. Because of this, he advises that it’s better to drink coffee between 9:30 a.m. and 11:30 a.m.
The Hong Kong Society of Sleep Medicine’s Dr. Samong Fong agrees. She says you should limit your intake to a few cups of coffee per day—and drink those before noon. “Consuming these drinks in the afternoon and evening can make it hard to fall asleep, or cause you to wake up during the night.”
3. Does coffee actually boost my energy levels?
“Caffeine blocks adenosine, a chemical that tells our brain we are tired,” says Esther Yuet Ying Lau, an assistant professor at the Education University of Hong Kong’s Psychology department. “Caffeine blocks ‘the sleepy signal’ to your brain, but does not provide additional energy.”
Indeed, the boost you get from coffee should be no substitute for the energy you get from proper rest. “Saying no to late-afternoon caffeine can be a step toward good sleep, which is the ultimate antidote to daytime sleepiness or fatigue,” adds Lau.
So instead of reaching for another cup of coffee—especially when you feel you already have reached your daily limit—go for a walk instead to reinvigorate yourself. Additionally, dehydration can leave you feeling tired, so a glass of water might be a better pick-me-up than a cup of java.
4. What’s the best roast to consume—and does adding milk help with digestion?
Research suggests that dark roast coffee, like espresso, French roast or Italian roast, is better for the stomach than lighter roasts. Dark roasts contain N-methylpyridium (NMP), a substance that tells the stomach to reduce the production of acid.
But the widespread belief that milk helps reduce stomach irritation is misplaced. While milk allows the creation of stable foams—perfect for picture-perfect lattes or cappuccinos—it actually stimulates acid production. The fat in milk temporarily coats the lining of the stomach, buffering the acid, but the relief only lasts 20 minutes or so.
Ultimately, however, what type of coffee you consume and what you add to it is all a matter of personal taste—and a recognition of what works best for you.
“Coffee is quite personal. I take a latte almost every time, my friend an almond latte, and my dad an espresso,” explains Christophe Younes, co-founder of Hong Kong–based café chain La Station. “You just need to know your body.”
Johan Nylander is an award-winning author and freelance correspondent based in Hong Kong. He has partnered with J.P. Morgan Private Bank to explore some of the most compelling aspects of Asia today.