Small doses of caffeine--even as little as that in one cup of coffee--can cause temporary stiffening of the blood vessel walls, according to two small studies released last week at the American Society of Hypertension's annual meeting.
Researchers from the Athens Medical School in Greece looked at the effect of caffeine in people with mild high blood pressure, and in individuals with normal blood pressure. The researchers found that people with mild hypertension who took a pill that contained 250 milligrams (mg) of caffeine, equivalent to the amount contained in 2 to 3 cups of coffee, experienced a temporary increase in blood pressure and in the stiffness of the aorta, the main artery leaving the heart.
In the other study, a small group of people with normal blood pressure who were given a pill containing as much caffeine as one cup of coffee also experienced a temporary increase in the stiffening of arterial walls.
Arteries need to be supple enough to expand when muscles--including the heart--demand more oxygen, and a loss of elasticity spells trouble for the body. Arterial stiffening places an extra load on the heart, and is a primary cause of hypertension.
The researchers explained that the increased arterial stiffness that comes with caffeine might worsen hypertension in people who already have high blood pressure, and may also increase the risk that these individuals have of suffering a heart attack or stroke. The increased stiffness also reduces the amount of oxygen that is supplied to the heart.
Both studies used only a small number of patients and further research is needed before doctors can make specific recommendations about who should avoid caffeine and who should simply reduce the amount they consume.
All research on this web site is the property of Leslie Beck Nutrition Consulting Inc. and is protected by copyright. Keep in mind that research on these matters continues daily and is subject to change. The information presented is not intended as a substitute for medical treatment. It is intended to provide ongoing support of your healthy lifestyle practices.