Java jitters

Quantity is key

September 13, 2007

Editor’s note: Catherine Bennett Dunster wrote the Health+Food column from June 2007 to April 2008.

“Drinking a cup or two of coffee has been a daily ritual of mine for 20 years. In recent months, I’ve heard that caffeine is beneficial to my health, but I’ve also heard that it’s dangerous. Should I drink more or cut back?”

Around the globe, taking coffee is as much a pastime as a drink. In fact, caffeine — the peppy chemical compound found in coffee — is one of the world’s most popular stimulants. Caffeine occurs naturally in more than 60 plants, including coffee beans, tea leaves, cacao pods, and kola nuts.

Increasingly, caffeine is also being added to our food supply. We’re used to having caffeine in sodas and energy drinks (such as Red Bull), but these days the stuff is being added to unusual suspects, such as sunflower seeds. Even something as innocuous as bottled water is no longer exempt from added caffeine.

Here are some typical beverages and the amount of caffeine they contain, according to the Mayo Clinic. (Note that the variation among coffee drinks is largely dependent on the quantity consumed.)

Item and quantityAmount of caffeine in milligrams
Plain brewed coffee, 8 oz. 135
Starbucks coffee, 16 oz. 259
Espresso, 1 oz. 30-50
Decaf coffee, 8 oz. 8
Black tea, 8 oz. 40-70
Green tea, 8 oz. 25-40
Diet Coke, 12 oz. 45
Pepsi, 12 oz. 37
Red Bull, 8.5 oz. 80

Given the popularity of caffeinated beverages, it’s not surprising that health research often focuses on caffeine, especially coffee. Frequent news headlines run the gamut from the common (“Caffeine causes nervousness and jitters”) to the obscure (“Caffeine produces greater attitude change towards a persuasive communication”).

(Forget alcohol, then. Serve that reluctant sweetheart an espresso instead.)

How much is too much?

There seems to be no end in sight for caffeine’s role as the darling of health research. Last month alone, a cursory look at the online health-research database Medline revealed three studies in which caffeine plays a central role: Older women can maintain cognitive function by drinking caffeine; drinking coffee may cut liver-cancer risk; and the chance of developing late-onset blepharospasm (eye-blinking spasms beginning in the fourth or fifth decade) is decreased in coffee drinkers.

In some circumstances, caffeine can even be considered a health food. But more often than not, it’s the negative effects of caffeine that garner the most attention. For example, caffeine impairs blood-sugar control in Type 2 diabetics, and caffeine intereferes with daytime sleep.

Though I love the speculative nature of much of this research, in truth these stories only add to the confusion and controversy when it comes to assessing whether caffeine is friend or foe — and certainly requires more thinking than you’d want to do before that first cup of joe in the morning.

There’s good reason to question both the effects and consumption of coffee. Caffeine is considered to be mildly addictive, and it can interfere with your sleep cycle and leave you feeling edgy and jumpy. It can also have modest cardiovascular effects, such as increased heart rate, increased blood pressure, and occasionally, irregular heartbeat. For those considering pregnancy, there is also some concern that caffeine can interfere with fertility.

However, the overwhelming consensus is that all of these risks are associated with excessive caffeine consumption. How much is too much? Five hundred to 700 milligrams, or the amount found in four or five cups of coffee.

Taken in moderation, caffeine may have some positive health benefits, increasing mental acuity and enhancing exercise performance. Most studies conclude that caffeine consumed prior to working out, for example, appears to extend endurance and decrease an athlete’s sense of exertion.

What it percolates down to is this: In moderate daily amounts (about 200 to 300 milligrams of caffeine, or the amount in two or three cups of coffee), there’s no reason to eschew caffeine.

But beware of hidden caffeine in your diet. Assess your current intake, and remember to include every source of caffeine that you consume — not just coffee. (That means sunflower seeds, if appropriate.)

Assessing how much caffeine you consume can be tricky. In the United States, food manufacturers are required to list caffeine as an ingredient, but not to list the total amount of caffeine contained in a product. Because caffeine is not on the Nutrition Facts label (and not all manufacturers voluntarily list the milligrams of caffeine per serving), an exact determination of milligrams consumed is challenging.

If you think you’re in caffeine-surplus mode — or if caffeinated drinks routinely displace more nutritious drinks, such as low-fat milk and 100 percent fruit juice, in your diet — it’s time to curtail your consumption. Those within the moderation guidelines who experience negative effects like jitters, racing heartbeat, or sleeplessness should consider drinking less, switching to decaffeinated options, or avoiding caffeine altogether.

But if, like many of us, you enjoy the aroma and flavor of a steaming cup of coffee, and it goes down without ill effects, then relax. And savor the ritual.

Catherine Bennett Dunster is a registered dietitian and a former instructor at Oregon Health and Science University. She lives with her husband and two children in Portland, Oregon.

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1. by James Berry on Sep 13, 2007 at 3:22 PM PDT

Katherine: thanks for putting my mind at ease. I discovered last year that having several cups of coffee in the morning, then several more at work about 10:00 am, was just too much for me. I cut down on what I drink at work, and feel much better for it. Gotta go, I’m getting sleepy... :0

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