by Marion Nestle
Apr 10 2012

Nutritionist’s Notebook: Caffeine Cravings

On Tuesdays, I answer questions about nutrition in NYU’s student newspaper, the Washington Square News.   These appear intermittently on the newspaper’s website.  Today’s is about caffeine.

Question: What kind of effect does caffeine have on our metabolism and general health? What is an appropriate amount of caffeine to have? And are certain sources of caffeine better than others? 

Answer: Caffeine is a mild upper. It perks up your central nervous system and makes you feel more alert, energetic and cheery. Caffeine is common in plants, but coffee, chocolate and tea have the most. The amount of caffeine depends on the type, amount used and brewing time, from 30 milligrams for a small cup of weak tea to more than 300 milligrams for some of the larger and stronger Starbucks drinks. When caffeine appears on the labels, you know exactly how much you are getting.

Energy drinks made for adults, like Red Bull, contain about 80 milligrams in an eight-ounce can. Coca-Cola, Pepsi-Cola and other soft drinks marketed to children have much less — 30 to 40 milligrams in 12 ounces.

People react to caffeine in different ways and, by this stage in your life, you undoubtedly know how much of it you can handle and at what time of the day you can handle it. If you take in more than your personal limit, you may feel nervous, shaky and sleepless. The more caffeine you drink, the more you become accustomed to it and the harder it is to give up. Some researchers think that the mix of sugar with caffeine is what makes some people feel addicted to soft drinks.

Perhaps it’s the caffeine in coffee that makes researchers want to find something wrong with it. I have a thick file of papers claiming that coffee raises the risk for heartburn, cancer, heart disease, infertility, ulcers and many other health problems, but the observed effects are small, inconsistent and unconvincing. When given as a drug, caffeine stimulates urine production and suppresses appetite, but the amounts in all but the strongest coffees are too low to produce such effects. If you get shaky when you drink caffeinated beverages, it’s time to stop.

—A version of this article appeared in the Tuesday, April 10 print edition. Marion Nestle is a contributing columnist. Email her questions at

Additional note on the food politics of caffeineSenatorDick Durbin (Dem-IL) has just asked the FDA to enforce its own rules on drink labeling.  Some makers of high-caffeine “sports” drinks are marketing them as dietary supplements to avoid having to adhere to FDA rules on how much can go into soft drinks.

  • I am clutching my morning cuppa for dear life as I read this…

  • brad

    I’m a person who gets into the habit of drinking coffee only if someone I live with drinks coffee, so coffee comes and goes in my life. When I don’t drink coffee for years and then start drinking it again, it has a predictable set of effects on me for the first week or so until I get used to it: shortly after drinking a cup I feel euphoric, then I pee gallons, and finally I get ravenously hungry. After a week everything settles down and I feel no noticeable effects at all after having coffee. At that point I can even drink a cup of non-decaffeinated coffee right before bed and have no trouble sleeping. It’s weird.

  • Keith Symcox

    I am curious what you think about this paper in Psychopharmacology, where the author states that the primary effects are actually from caffeine withdrawal. In other words, caffeine picks you up (after the initial dose), not by the effect of caffeine, but rather by negating the withdrawal symptoms.
    Psychopharmacology (2005) 179: 742–752

    I know that personally, getting off caffeine improved sleep patterns, and rid myself of the midafternoon “crash” that I used to have.

  • Cathy Richards

    Marion, Wonder if you know the answer to this — I’ve been trying to find research on the genetic variants of caffeine metabolism. There seemed to be some papers out around 5-8 years ago about slow and fast caffeine metabolizers and how their caffeine-associated health risks were markedly different (slow metabolizers much more likely to have MIs, arrhythmia, anxiety, etc). None of my health colleagues seem to know about this, so am wondering if the theory is still being explored or if it has been debunked?

  • Marion

    @Cathy Richards: As I read the literature on caffeine metabolism, the rate of disappearance varies widely among individuals. People who metabolize it quickly, show few symptoms. The Wikipedia entry on caffeine, which looks quite good, includes this statement: “A 2011 analysis published by PLoS Genetics reviewed five studies covering more than 47,000 subjects of European descent. Researchers determined that habitual caffeine intake is associated with variations in two genes that regulate how quickly the body processes caffeine.”

  • Pingback: Tom Douglas » Blog Archive » Food in the News/ by Shelley Lance, Blog Editor()