I’ve noticed that after dinner I often feel lightheaded and dizzy. And after a particularly heavy meal one day last week I fainted. I’m 78, in reasonable health with the exception of mild high blood pressure. What could be causing this?
You may be experiencing something called postprandial hypotension. This is a sharp decrease in blood pressure that occurs after eating a meal with symptoms that can include dizziness, light-headedness, fainting and falls. In order to digest food, the intestines require an increased amount of blood. As blood flows to the intestine after a meal, it causes the heart rate to increase. At the same time, blood vessels in other parts of the body constrict to help maintain blood pressure. In some older people, this mechanism does not work smoothly. In these cases when the blood flows to the intestine, the heart rate does not increase adequately and blood vessels do not constrict enough to maintain blood pressure. As a result, blood pressure falls.
Postprandial hypotension occurs more commonly in older people, but is unusual in younger people. It is more likely to occur in those suffering with high blood pressure or other disorders such as Parkinson’s disease or diabetes that interfere with the actions of the autonomic nervous system, which is responsible for regulating internal body processes.
How can I be sure this is what is causing my problem? And if it is postprandial hypotension, what can be done about it?
To diagnose postprandial hypotension, your doctors will have to measure your blood pressure before and after meals to determine if this is the cause of your symptoms. Generally, people who have symptoms of postprandial hypotension should not take antihypertensive drugs before meals and should lie down after meals. Taking a smaller dose of antihypertensive drugs and eating small, low-carbohydrate meals more frequently may help reduce the effects of this disorder.
For some people, walking after a meal helps improve blood flow, but blood pressure may fall when they stop walking. Taking medications, such as non-steroidal anti-inflammatory drugs (NSAIDS) and other drugs that cause salt to be retained, before a meal may help increase blood volume.
In very severe cases where symptoms do not respond to other measures and admission to hospital is required, injections with the drug octreotide may help by reducing the amount of blood flowing to the intestine.
