A dizzy or lightheaded feeling after eating a meal could be the result of a common condition called postprandial hypotension (low blood pressure after eating), reports the Harvard Heart Letter. Digestion is a complicated job that requires coordination among the digestive, nervous, and circulatory systems. To compensate for blood going to the stomach and small intestine during digestion, the heart beats faster while blood vessels narrow. When the heart and blood vessels do not respond normally, the blood pressure drops. Postprandial hypotension announces itself as dizziness and lightheadedness causing some people to fall, others to faint. It can trigger chest pain, disturb vision, or cause nausea. In some people, it stems from aging-related changes that interfere with the body’s ability to respond to sudden changes in blood pressure. There is no surefire treatment for postprandial hypotension; however, several lifestyle changes can be helpful: (1) drink 12 to 18 oz of water 15 minutes before eating, (2) try 6 or 7 smaller meals a day, as larger meals may trigger the response, (3) foods made with white rice, refined flour, and potatoes, as well as sugary beverages, pass quickly from the stomach to the small intestine, which contributes to postprandial hypotension; eat slowly digested foods, ie, whole grains, beans, and protein, to keep your blood pressure up, (4) blood pressure usually hits bottom 30 to 60 minutes after a meal; sitting or lying down for an hour after eating is another way to cope with postprandial hypotension.
(Source: Harvard Heart Letter, July 2010, Harvard Health Publications, health.harvard.edu)