Coffee is a popular beverage, usually made through the filtration of water through the ground beans of the coffee plant. Because this beverage is extracted from a plant, it contains several plant-based compounds such as phytonutrients, diterpenes and caffeine. Drinking too much coffee, like overconsumption of any food or beverage, can have adverse effects. These can include insomnia, anxiety and increased blood pressure, mainly due to the effects of excessive amounts of caffeine. Drinking too much coffee may also affect the integrity of your immune system, both directly and indirectly. Check with your doctor before making any significant dietary changes.
Naturally Occurring Substances in Coffee
The most well-known substance found in coffee is caffeine, a mild stimulant that can increase alertness and concentration. In addition to caffeine, according to the Linus Pauling Institute at Oregon State University, coffee contains diterpenes, which can raise your cholesterol, and chlorogenic acid, an antioxidant. In lesser, but still significant amounts, coffee also contains amino acids, vitamins, minerals and polyphenols. Coffee also contains substances that draw water out of your body, acting as a mild diuretic. Filtered coffee, in contrast to French-pressed or boiled coffee, contains significantly fewer diterpenes.
Too Much Coffee and Your Immune System
Although consuming too much coffee can lead to problems sleeping or anxiety, it does not appear to hurt your immune system directly. A 1990 study published in the "Journal of Immunopharmacology" found no effects on the number of immune system T or NK, or natural killer, cells after drinking coffee. The study did find that levels of both PHA and Con A were suppressed in the subjects, an indicator of decreased lymphocyte immune cell production. More research is needed to understand this mixed mechanism and its implications. Indirectly however, drinking too much coffee can deplete your immunity through sleep disruption, according to the National Institute of Neurological Disorders and Stroke.
How Much Coffee is Too Much?
Moderate consumption of 200 to 300 milligrams of coffee daily doesn't appear to have adverse effects for most people. If however, you have a sensitivity to stimulants, consider consuming less or use decaffeinated coffee instead. Avoid the potential cholesterol-raising effects of diterpenes by choosing filtered coffee or using non-filtered coffee in moderation. According to the National Sleep Foundation, the stimulating and sleep-disturbing effects of caffeine can last for six or more hours. In order to avoid sleep impairment that can lead to immune system decline, stop consuming coffee or other caffeinated products in the afternoon, or approximately six hours before going to sleep.
Coffee and Cortisol
Coffee does not appear to hurt the immune system directly, but it can increase levels of the stress hormone cortisol, which is associated with decreased immunity. A 2008 study published in "Pharmacology Biochemistry and Behavior" found that participants who consumed caffeine prior to physical activity had higher cortisol levels than individuals who did not consume caffeine. Increased levels of cortisol were found to be associated with decreased immunity in a 2009 study published in "Brain, Behavior and Immunity." These findings suggest that consuming large amounts of coffee may increase cortisol levels, leading indirectly to a decline in the effectiveness of the immune system.
References
- National Institutes of Health: Caffeine in the Diet
- "International Journal of Immunopharmacology"; Coffee and the Immune System.; I. Melamed, et al.; 1990
- Linus Pauling Institute at Oregon State University: Coffee
- "Brain, Behavior and Immunity"; Depression, Cortisol, and Suppressed Cell-Mediated Immunity in Metastatic Breast Cancer.; S. E. Sephton, et al.; 2009
- "Journal of the American Medical Association"; Suppression of Lymphocyte Stimulation Following Bereavement; Steven J. Schleifer, MD, et al.; 1983
- National Institute of Neurological Disorders and Stroke: Brain Basics: Understanding Sleep
- National Sleep Foundation: Caffeine and Sleep
- "Pharmacology, Biochemistry and Behavior"; Cortisol Responses to Mental Stress, Exercise and Meals Following Caffeine Intake in Men and Women; William R. Lovallo, et al.; 2006
