An Overview of Postprandial Hypotension

Postprandial hypotension is a condition in which a person’s blood pressure drops after they eat. (“Postprandial” means “after a meal.”) For people who have postprandial hypotension, the simple act of standing up after a meal can produce a particularly dramatic drop in blood pressure, leading to significant symptoms.

Postprandial hypotension is most commonly seen in elderly people. Up to one in three older adults will have some degree of postprandial hypotension, defined as a drop in the systolic blood pressure of up to 20 mmHg within two hours after a meal. For most of these individuals, the condition is mild and is not associated with symptoms. In some, however, postprandial hypotension can become quite severe.

Postprandial hypotension is one particular form of orthostatic hypotension (a drop in blood pressure when standing up). All types of orthostatic hypotension are more likely to affect people with high blood pressure, or with certain conditions that impair the autonomic nervous system such as Parkinson's disease and diabetes.

People who have postprandial hypotension will often notice lightheadedness, dizziness, weakness or even syncope (loss of consciousness) when they stand up within one or two hours after eating a meal. Symptoms tend to be more severe after eating a large meal, a meal that includes a lot of carbohydrates, or if alcohol is consumed during or prior to eating. These symptoms usually resolve within two hours or so after finishing the meal.

While the cause of postprandial hypotension is not completely understood, it is thought to be related to the pooling of blood in the abdominal organs during the process of digestion.

Because of this blood pooling, the amount of blood available to the general circulation drops, causing the blood pressure to fall, especially when standing.

Some amount of blood accumulation in the abdominal organs after a meal is normal since digesting food requires an increase in blood flow. In people with postprandial hypotension, however, it is thought that this pooling of blood in the gut is exaggerated, or that the normal reflex that constricts the blood vessels in the legs (to compensate for the abdominal blood pooling) is diminished.

Eating high-carbohydrate meals appears to worsen postprandial hypotension. This observation has led some experts to theorize that, in people with postprandial hypotension, insulin or other blood chemicals that are released in response to a high-carb meal may cause excessive dilation of the abdominal blood vessels.

To some extent, aging itself is accompanied by an increase in the abdominal blood pooling that normally occurs after a meal. Most older people never develop symptoms from this increased blood pooling — but people who do have significant symptoms from postprandial hypotension tend to be elderly.

While there is no specific treatment to eliminate postprandial hypotension, symptoms can be controlled adequately in the large majority of people who have this condition. Treating the symptoms of postprandial hypotension involves four elements:

• Eat smaller, more frequent meals. Eating large meals tends to exaggerate abdominal blood pooling. Smaller meals mean less blood pooling.
• Avoid high-carbohydrate meals.
• Avoid alcohol. Alcohol relaxes blood vessels and tends to prevent the constriction of blood vessels in the legs that would normally compensate for abdominal blood pooling.
• Stay seated — or, if symptoms are severe, lie down — for an hour or two after eating. The abdominal blood pooling tends to dissipate within this time after a meal.

If these measures are insufficient, other therapies commonly used to treat orthostatic hypotension are often helpful. For example, taking nonsteroidal anti-inflammatory drugs (NSAIDs) prior to a meal can cause salt to be retained, thereby increasing blood volume.

In addition, caffeine can cause blood vessels to constrict and may reduce symptoms. Guar gum may also improve symptoms, possibly by slowing the emptying of the stomach after a meal. Getting plenty of exercise between meals — such as walking — can improve vascular tone, and diminish symptoms of postprandial hypotension.

It has been found that in people with postprandial hypotension who also have diastolic heart failure and are being treated with diuretics, withdrawing the diuretics may dramatically improve symptoms.

If symptoms are severe and cannot be controlled by other measures, subcutaneous injections of octreotide (a drug that behaves like somatostatin, a hormone produced by the pancreas) before a meal may help reduce the amount of blood flowing to the intestine. However, this treatment is quite expensive and can cause significant side effects.

While postprandial hypotension can occasionally become a significant problem, especially in the elderly, in the large majority of people who have this condition, symptoms can be controlled with a few lifestyle changes.