If you're one of the 56 percent of adults that drink coffee daily, you're probably hoping for an energy boost instead of relaxation. But scientists are discovering that coffee may have the potential to reduce emotional and physical stress. In the same way that coffee affects brain chemistry to keep you alert, its effects on neurotransmitters may help your body fight off symptoms of stress and stress-related diseases.
A Japanese study investigated coffee on its own and also its individual components, caffeine and chlorogenic acid -- a type of plant-based antioxidant -- for their stress-relaxing benefits on the hippocampus region in rat brains. The researchers looked at the interaction of coffee with the brain chemicals serotonin and dopamine, two neurotransmitters linked to emotions. The results, published in a 2002 issue of "Neuroscience Letters," found that coffee reduced stress chemical response in the rats when they were put through stressful conditions.
Stress and Blood Pressure
Researchers in Switzerland found that coffee affected stress-induced high blood pressure differently in subjects who were habitual drinkers versus those who rarely drank coffee. The study, published in 2005 in "Hypertension," showed that coffee caused a rise in blood pressure under stressful situations in the non-drinkers, but in those who drank coffee regularly, their blood pressure wasn't affected by stress, indicating a potential cumulative calming effect. However, an earlier study in 1992, published in "Psychosomatic Medicine," found that 6 cups of caffeinated coffee a day increased the heart rate response to mental stress in 43 healthy subjects.
The third trimester of pregnancy is stressful for many women due to the physical changes of added weight, strain on internal organs, back pain, frequent urination and heartburn. A Japanese team studied the effect of coffee consumption on stress in pregnancy, determined by levels of cortisol, or "the stress hormone." The study results, published in 2006 in the "International Journal of Gynaecology and Obstetrics," found that cortisol levels in the pregnant women were significantly reduced after coffee intake. However, March of Dimes recommends that you consume no more than two 8-ounce cups of coffee a day while pregnant.
The coffeemaker is a staple in most offices, but as one study published in 2007 in the journal "Psychoneuroendocrinology" indicates, that may not be a good thing when it comes to work-related stress. Health care workers who drank the most coffee had the greatest levels of the stress hormone cortisol in the evening after a day at work. However, this cortisol increase was also linked to decision authority, and it may be that those with the most responsibility also drank the most coffee. A second unpublished study at the University of Bristol in the U.K. found that consumption of caffeinated coffee in a work environment made men feel more stressed, although it tended to reduce stress for women.
Staying up all night to cram for exams while guzzling coffee is a familiar rite of college, but sleep deprivation can be stressful to your body. A study published in 2008 in the "Journal of Agricultural and Food Chemistry" found that the smell of coffee alone may help fight sleep-deprivation stress. When researchers tested the aroma of roasted coffee beans on mice in the lab, several genes in the mice were activated, including some that produce proteins with healthful antioxidant activity and reduce cortisol.
- CNN.com: Coffee: Is it Healthier Than You Think?
- Hypertension: Coffee Blunts Mental Stress–Induced Blood Pressure Increase in Habitual but Not in Nonhabitual Coffee Drinkers
- International Journal of Gynaecology and Obstetrics: Effect of Coffee Intake on Blood Flow and Maternal Stress During the Third Trimester of Pregnancy
- March of Dimes: Foods to Avoid or Limit During Pregnancy
- Neuroscience Letters: Modulation of the Stress Response by Coffee
- Psychoneuroendocrinology: Coffee, Stress and Cortisol in Nursing Staff
- Psychosomatic Medicine: Effects of Coffee on Cardiovascular Responses to Stress
- Journal of Agricultural and Food Chemistry: Effects of Coffee Bean Aroma on the Rat Brain Stressed by Sleep Deprivation
- National Coffee Association: 2010 National Coffee Drinking Trends Study
- Bristol University: Stressed at Work? Taking a Coffee Break Might Make Things Worse