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Saturday, December 9, 2023
Dec. 9, 2023

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More coffee? OHSU expert says there’s little danger of caffeine overdose

Your body knows how much is too much, doctor says

By , Columbian staff writer

I’ve got to cut back on this stuff, it’s driving me crazy.

No, wait! I need another cup!

Know how that feels? Too many people do, especially in the Pacific Northwest, the birthplace of Starbucks. In these dark, soggy climes, coffee can become more than launchpad fuel for the day. It’s a pastime. It’s a religion. It’s a nutrient essential to life.

About 80 percent of American adults take some form of caffeine daily, according to the U.S. Food and Drug Administration.

Does that mean we are all, you know, addicts? How concerned about that should we be?

Not too concerned, said Dr. Suzanne Mitchell, a professor of behavioral neuroscience and psychiatry at Oregon Health & Science University.

“I think caffeine is a fairly harmless stimulant,” she said.

Using caffeine to power up in the morning and maybe add extra boost to your afternoon is only a problem when that becomes full-blown “caffeine use disorder,” Mitchell said. That’s a fairly new — and rarely applicable — entry in the official psychiatric diagnostic manual used by health care professionals, she said.

To Learn More

Center for Science in the Public Interest’s thorough caffeine chart: www.cspinet.org/caffeine-chart

There are three essential elements to caffeine use disorder. One, you have a persistent desire to cut down or quit. Two, you keep using caffeine despite experiencing problems with it. Three, you experience symptoms of withdrawal when you stop.

While caffeine use disorder can be a real thing, Mitchell said, a 2020 study published in the Journal of Caffeine and Adenosine Research estimated that less than 10 percent of people fit the definition.

Many have one or even two of those use-disorder symptoms, Mitchell said. Many people feel headachy without coffee. Some feel anxious, jittery and sleepless after they’re fueled up, and think about quitting. That does make it sound similar to a smoking or drinking habit.

“But unless it’s all three, we don’t think of it as a disorder,” Mitchell said. “Having a desire for caffeine and wanting to avoid withdrawal are not big societal problems, like other use disorders.”

Caffeine just isn’t that strong nor that dangerous compared with other stimulants, she said. Habituation to it doesn’t seem to lead to widespread public health or social problems, unlike tobacco, alcohol and especially hard drugs.

“Spending all your money and losing your family over coffee — it’s not usually a thing,” she said.

Coffee drinkers are willing to live with the knowledge they’d suffer mild withdrawal effects — headaches, irritability, fatigue — if they quit their habit.

“There isn’t a medical incentive to stop using caffeine,” Mitchell said. “The amounts people ordinarily consume shouldn’t lead to negative health effects … but they will be enough to cause some symptoms of withdrawal if you go cold turkey.”

If you do feel like cutting back, do it gradually. Try weaker coffee, or tea or some other hot drink, even hot water with lemon.

“It’s all about the routine,” Mitchell said. “You might just be able to trick yourself.”

Energy vs. anxiety

Caffeine increases energy, alertness and a feeling of well-being because of its interaction with the dopamine system, Mitchell said.

Dopamine is the “happy hormone.” Caffeine elevates the amount of dopamine in the brain. It also stimulates the release of adrenaline, the stress-and-excitement hormone.

Heroin and cocaine do the same thing, Mitchell said, but they are dramatically stronger.

“The dose makes the poison” is how it’s put in the field of toxicology, she said, given that ingesting too much of any substance, even water or oxygen, can be dangerous.

“That saying is so applicable to caffeine,” she said. “We are used to taking in a little bit of caffeine and having effects that we enjoy. But if you take a lot, those effects are going to change so you no longer feel so good.”

Common symptoms of caffeine sensitivity are anxiety, restlessness, headaches, racing heartbeat and temporarily elevated blood pressure. Further symptoms can be diarrhea, sour stomach and vomiting.

The negative effects of overdoing caffeine tend to turn into a self-regulating system, Mitchell said. When you’re wracked with jitters and anxiety, it’s easy to realize the cause and hit the brakes even at the cost of milder discomforts, like headaches and crankiness.

“Immediate negative effects are the reason it doesn’t turn into a runaway train,” Mitchell said.

Sleep and science

Caffeine can drive a cycle of insomnia, Mitchell said. While its half-life in the body is about five hours (that’s how long it takes for the body to eliminate half the caffeine you’ve ingested), the rest can stay with you for much longer.

Caffeine may delay the timing of your body clock and affect total sleep time, according to the American Academy of Sleep Medicine. “Caffeine can also reduce the amount of deep sleep that you enjoy,” the AASM says.

If you’re concerned about caffeine’s effect on your sleep, follow the guidelines shared by the AASM and the FDA: Limit yourself to no more than 400 milligrams of caffeine per day, that is, no more than four 8-ounce cups. Definitely abstain from caffeine in the late afternoon and evening, when it’s likeliest to affect your sleep.

Other guidelines: People with high blood pressure or heart problems should avoid high levels of caffeine. Pregnant or nursing women should limit or avoid it completely. Everyone should stay away from pure powdered caffeine.

Science still has a lot to learn about caffeine, Mitchell said. Some studies have suggested that sleep problems occur because caffeine ingested later in the day is metabolized more slowly. Researchers also want to learn why caffeine affects women more intensely than men, and younger people more intensely than elders. They want to study why people develop tolerance over time and seem to require a baseline dose to avoid withdrawal.

Caffeine may even have medical applications, Mitchell said.

“There are implications for how it might be used with … disorders that result in apathy and inactivity, like depression,” she said.

Focus on dose

It can be hard to know exactly how much caffeine you’re ingesting. Depending on whether you made instant at home or bought it at Starbucks, the same size cup of coffee may contain very different amounts of caffeine.

“Increase your awareness of what products contain caffeine so you are not accidentally taking more than you want,” Mitchell said.

According to the FDA, a typical 8-ounce cup of brewed coffee contains 80 to 100 milligrams of caffeine. The same amount of instant coffee has about 60 milligrams, while the same amount (a “short”) of Starbucks Pike Place medium brew contains 155. (Starbucks posts all nutrition details for its products; visit starbucks.com, find your favorite and click on “Full nutrition and ingredients list.”)

The same amount of Starbucks dark roast has less: 130 milligrams. That’s conventional wisdom turned on its head. While more flavorful, darker roasts generally contain a little less caffeine than lighter roasts.

Most black and green teas contain substantially less: 80 milligrams and below. One can of Coca-Cola contains 39 milligrams. Energy drinks can zoom to as much as 250 milligrams or even more per 8 ounces.

Check the Center for Science in the Public Interest’s exhaustive listing of the caffeine content of most food and drink products at cspinet.org/caffeine-chart.

If you’ve read this far, it’s because you’re hungry to know whether chocolate is keeping you awake at night. According to the CSPI chart, it’s not likely. One Hershey bar contains 10 milligrams of caffeine. The average chocolate brownie has 1 milligram.

At that rate, you could eat 400 brownies per day and still meet the FDA’s caffeine guideline. But then you’d have other problems.

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