The answer might change what you order tomorrow
If you reach for coffee or tea every morning, you’re already doing something good for your brain. Both drinks protect against depression. But how much you drink, and which one you choose, makes a difference.
Tea Wins for Mood
Drinking tea lowers depression and sharpens concentration, and the benefits rise the more you drink, up to 6 cups a day. Those numbers come from a review of 11 studies covering nearly 23,000 people.
Green and black teas both deliver these benefits. Herbal teas don’t. That’s because herbal teas don’t use leaves from the Camellia sinensis plant, the source of tea’s mood-protecting compounds.
Caffeine alone doesn’t explain it. Tea carries several ingredients that protect brain cells: catechins, flavonoids, polyphenols, and L-theanine. That last one, L-theanine, also calms the jittery edge that caffeine sometimes causes.
A 2021 Japanese study put this to the test, as Dr. Aiken reviewed for Psychiatric Times. Researchers split participants into two groups. One drank a daily cup of matcha (a strong powdered green tea), and the other took the same amount of caffeine in a pill. After one day, both groups showed a similar mental boost. But after three months, the caffeine pill group lost those gains. The matcha drinkers kept improving in mental speed and attention.
Coffee Helps Too, Up to a Point
Coffee also lowers depression risk, but only up to about one and three-quarter metric cups a day, roughly one large mug. After that, the benefits level off. Push past two mugs a day, and the risk of depression starts to climb. That pattern comes from studies involving nearly 340,000 people.
The reason comes down to caffeine.
How Much Caffeine Is Too Much?
A small amount of caffeine lifts mood, regardless of where it comes from. The safe upper limit is about 300 mg per day. Above that, the risk of depression rises.
To put that in perspective, here’s how many metric cups (the kind used in baking) you’d need to drink before crossing that line:
Notice where tea falls on that list. You’d need to drink ten cups of green tea a day to reach the danger zone. With coffee, you get there at two mugs.
For alertness, a half cup (that’s metric cups) of coffee every few hours is about all you need. More than that tends to go to waste, or worse, trigger anxiety.
Anxiety is one of the most common side effects of caffeine. If you deal with anxiety and haven’t tried cutting caffeine, it’s worth a two-week experiment. Taper slowly to avoid headaches.
Timing matters too. A 2023 study found that morning coffee lowered depression risk, while afternoon coffee raised it. The likely reason: afternoon caffeine disrupts sleep, and poor sleep fuels depression.
Other Health Benefits
Both coffee and tea lower the risk of diabetes, dementia, cancer, liver disease, and heart disease. Adding sugar, honey, or artificial sweeteners erases many of those benefits. Xylitol, a plant-based sweetener, is one of the better options if you need something sweet.
Tea has an edge for physical health as well. The high caffeine in coffee can aggravate certain heart conditions, and even decaf coffee contains acids that worsen heartburn. Tea’s L-theanine also helps keep blood pressure from rising, which caffeine tends to do on its own.
The Downside: Caffeine Dependence
Caffeine builds dependence fast, sometimes within just a few days. As tolerance grows, you need more to feel the same effect.
Too much caffeine can cause anxiety, a racing heart, high blood pressure, heartburn, tremor, and insomnia. These problems are milder with tea, partly because its other compounds moderate the effects. Caffeine also amplifies the side effects of some medications, including ADHD stimulants like Adderall, Vyvanse, Ritalin, Concerta, and Focalin, as well as the wakefulness drugs Nuvigil and Provigil.
How to Cut Back Without Feeling Awful
If caffeine is causing insomnia, anxiety, tremor, dry mouth, heartburn, or high blood pressure, cutting back makes sense. But don’t stop cold. Withdrawal symptoms, including headaches, irritability, fatigue, muscle aches, and mental fog, start within 12 to 24 hours of your last drink.
Lower your intake gradually, reducing the dose every two to three days using the amounts below. If symptoms appear, slow down. Drinking more water, sleeping well, and getting exercise all make the process easier.
The bottom line
Tea offers more mood protection with a wider safety margin. If you already drink coffee, one mug in the morning hits the sweet spot. Either way, what’s in your cup matters more than most people realize.
—Chris Aiken, MD
Director, Psych Partners
Editor in Chief, Carlat Psychiatry Report
