Why eating may provoke low blood pressure

If after eating a meal you experience symptoms of feeling dizzy or light-headed to the point of fainting or making you afraid you might fall, you may be experiencing a condition called postprandial hypotension.   These symptoms are due to an abnormally excessive decrease in blood pressure occurring after a meal.

Diagnosing postprandial hypotension

Diagnosis is required by a doctor to determine if this is what you may have.  Doctors will measure blood pressure both before and after a meal to determine if postprandial hypotension is the cause. Some doctors define low blood pressure as a reading lower than 90 mm Hg systolic or 60 mm Hg diastolic.  It really depends on how you feel when your blood pressure is low but let your doctor determine his interpretation of defining low blood pressure.

Up to one-third of older people are affected by this postprandial hypotension but it is hardly ever seen in younger individuals. 

Causes of postprandial hypotension

Certain people are genetically predisposed to postprandial hypotension or in those who already have high blood pressure or brain disorders controlling the autonomic nervous system – Parkinson disease, multiple system atrophy (Shy-Drager symdrome), and diabetes.

The main reason why blood pressure would drop after eating is due to the process of digestion.  Digesting food is complex requiring a large amount of blood.  When food is eaten, blood rushes to the intestine causing the heart rate to increase while blood vessels constrict in other parts of the body helping maintain blood pressure. In younger individuals this all works like it should and does not cause a decrease in blood pressure.

However for some older adults things may not be working quite as well.  The blood will still flow to the intestine but the heart rate does not elevate as much as it should causing the blood vessels to not constrict enough to maintain blood pressure.  Blood pressure falls as a result of this.

Preventing postprandial hypotension

Once a diagnosis is made and it is determined you are experiencing postprandial hypotension, there are some steps you can take to prevent it from happening:

·         Do not take antihypertensive drugs before meals.

·         For some people lying down after a meal helps – blood pressure will hit bottom 30 to 60 minutes after a meal. 

·         For other people walking after a meal improves blood flow but once you stop walking, the blood pressure may fall.  Be careful for signs of your blood pressure falling. 

·         Taking a nonsteroidal anti-inflammatory (NSAIDs) before a meal can cause salt to be retained helping to increase blood volume.

·         Drink 12 to 18 ounces of water before eating to reduce a fall in blood pressure.

·         Eat smaller meals.  Large meals can trigger a drop in blood pressure so try switching from three meals a day to six or seven meals a day.

·         Eat fewer carbohydrates that are rapidly absorbed.  These foods are broken down rapidly passing quickly from the stomach to the intestine which can provoke postprandial hypotension.  Reduce intake of easily digested carbs which include white bread and any other food made with highly refined white flour, white rice, potatoes, and sugary beverages.  Consume more slowly digested foods such as 100% whole wheat bread, beans, protein, vegetables and healthy oils.