Thanks to a new analysis from the famous Harvard Nurse's Health Study, I have a mile-wide smile as I pour my morning coffee. This particular study looked at caffeine's effect on depression in over 50,000 women who worked in healthcare. It showed that women who consumed two to three cups of caffeinated coffee per day were 15 percent less likely to develop depression compared to those who drank one cup. Women who drank at least four cups per day had a 20 percent lower risk of depression.
So, the study suggests caffeinated coffee may have a possible protective effect against depression. With one out of five American women suffering from depression at some point in their lives, this is news you can use. And the truth is, there are many possible benefits to caffeine that most people are not familiar with. So I'd like to decode some of the "buzz."
First, I must disclose that I'm biased. I love my caffeine. As a lifelong athlete, my fellow exercise buffs and I experience the possible benefits of caffeine first-hand. And the proof is in the science. The American College of Sports Medicine suggests that caffeine consumption increases physical performance during both short-term and endurance exercise, and thank heavens for that.
I find this to be true in my own daily routine. Mornings begin with the smell of my "get up and go fast" brew in the kitchen before I fly out the door on my way to a run or the gym. Hot or cold peach and mint-flavored green tea drinks keep my momentum going during the day. And now, as I train for the 2012 Boston Marathon, I have a cup'a Joe each morning to give me the extra boost for long runs and cross training sessions.
As a physician, I'm asked about caffeine all the time by my patients. "Is it okay to drink caffeine?" "How much is too much?" and "What does it do to my body?"
Here's a quick caffeine 101:
Sometimes people get jittery (pun intended) when it comes to caffeine consumption. However, I like to remind them that it occurs naturally in more than 60 plants, so mankind has been safely consuming it for millennia. And more than 140 regulatory agencies throughout the world, including the U.S. Food and Drug Administration, consider caffeine a safe ingredient.
Caffeine is in some of our favorite things like coffee beans, tea leaves and chocolate. Many people are surprised to find that it's also in foods like some yogurt and ice creams. In fact, caffeine is so popular, it is considered the most common central nervous system stimulant consumed globally, with more than 80 percent of caffeine consumed through coffee drinking.
When it comes to how much caffeine to consume, the Mayo Clinic defines moderate caffeine consumption for most healthy adults as 200 to 300 milligrams -- the amount in about two to four cups of brewed coffee a day. It suggests that 500-600 milligrams can cause some restlessness and sleep issues in some people.
Portions are also important. For those of you who tend to go way overboard, consider reining it in -- and don't drink an entire pot at a time. And, clearly talk with your medical team if you have any questions about how much you should be consuming. To enlighten you and help you navigate, here's a look at the spectrum of average caffeine content in common foods and drinks:
• Drip coffee, 7 fl oz., 115-175 mg
• Percolated coffee, 7 fl oz., 80-135 mg
• Espresso coffee, 1.5-2 fl oz., 100 mg
• Guayaki yerba mate, 0.2 oz., 85 mg
• Red Bull, 8.2 fl oz., 80 mg
• Black tea, 6 fl oz., 50 mg
• Coca-Cola Classic, 12 fl oz., 34 mg
• Green tea, 6 fl oz., 30 mg
• Decaffeinated coffee, 7 fl oz., 5-15 mg
• Hershey's Special Dark (45 percent cacao), 1 bar of 1.5 oz., 10 mg
(Source: Nutrition Action)
So, what does caffeine do when it hits our system? First, it releases glucose into our blood stream, so we have extra fuel. Stress hormones and adrenalin naturally do this when we have a "fight and flight response." Caffeine can augment this effect -- increasing our amount of available fuel.
A 2010 study in the International Journal of Sports Nutrition and Exercise Metabolism found that athletes who consumed both healthy carbs and caffeine had nearly 70 percent more glucose fuel in their bodies than those who only consumed carbs. And, caffeine causes our brains to produce higher levels of dopamine, the brain chemical that floods us with a sense of pleasure. No wonder we feel good and depression is left in the dust.
After an average dose of caffeine, most people feel more awake, energized and focused. If you overdo it relative to your unique medical and physical make up, then you can experience over-stimulation. Some people can drink an espresso with dinner and fall asleep with no problem. Other people know to cut off caffeine consumption mid-afternoon. If you are sensitive to caffeine, consider doing what I do and go half-caffeinated. I don't need much to get me going, but like to drink my full cup. You can buy half-caffeinated beans at lots of stores, including Whole Foods.
And, of course, always talk with your medical team about questions you have regarding your caffeine consumption, nutrition and physical fitness. Everyone is different, so you want to pay attention to what your body needs. Right now, my body is calling for another sip of energy. Let's all drink to that!
Dr. Pamela Peeke is an internationally recognized expert, physician, scientist and author in the fields of nutrition, stress, fitness and public health. She is Chief Medical Correspondent for "Discovery Health TV," and author of the bestselling books "Fit to Live," "Body for Life for Women," and "Fight Fat After Forty." She serves as a frequent commentator for national broadcast networks and works with several food and beverage companies including The Coca-Cola Company. Dr. Peeke holds the position of Assistant Clinical Professor of Medicine at the University of Maryland, School of Medicine and is a Fellow of the American College of Physicians.