When your blood pressure drops after you eat a meal, the condition is known as postprandial hypotension. Postprandial is a medical term that refers to the time period right after a meal. Hypotension means low blood pressure.
Blood pressure is simply the force of blood flow against the walls of your arteries. Your blood pressure changes throughout the day and night based on what you’re doing. Exercise can cause a temporary rise in blood pressure, whereas sleeping usually brings your blood pressure down.
Postprandial hypotension is common, affecting about a third of older adults. A drop in blood pressure can lead to lightheadedness and falls, which may lead to serious complications. Postprandial hypotension can be diagnosed and managed, often with some simple lifestyle adjustments.
The main symptoms of postprandial hypotension are dizziness, lightheadedness, or fainting after a meal. Syncope is the term used to describe fainting that occurs as a result of falling blood pressure.
Usually this condition is caused by a drop in your systolic blood pressure after eating. The systolic number is the top number in a blood pressure reading. Checking your blood pressure before and after a meal can reveal whether a change takes place while you’re digesting.
If you have drops in blood pressure at other times that aren’t associated with eating, you may have other conditions unrelated to postprandial hypotension. Other causes of low pressure may include:
As you digest a meal, your intestine requires additional flow of blood to work properly. Normally, your heart rate would increase while your arteries that are supplying blood to areas other than your intestines would constrict. When your arteries narrow, the pressure of blood flow against artery walls increases. That, in turn, increases your blood pressure.
These changes in your blood vessels and heart rate are managed by your autonomic nervous system, which also controls many other body processes without you having to think about them. If you have a medical condition that affects your autonomic nervous system, your heart rate may not increase, and certain arteries may not constrict. Blood flow will remain normal.
However, as a result of your intestine’s extra demand for blood during digestion, blood flow to other parts of the body will decrease. This will cause a sudden, but temporary, drop in blood pressure.
Another possible cause is related to a fast absorption of glucose, or sugar, and may explain the higher risk in patients with diabetes.
However, you can develop postprandial hypotension even if you don’t have a condition that affects the autonomic nervous system. Sometimes, doctors are unable to determine an underlying cause for postprandial hypotension.
Old age increases your risk of postprandial hypotension and other forms of low blood pressure. Postprandial hypotension is rare among young people.
Certain medical conditions can also increase your risk for postprandial hypotension because they may interfere with the parts of the brain that control the autonomic nervous system. Parkinson’s disease and diabetes are two common examples.
Sometimes, people with hypertension (high blood pressure) can experience significant drops in their blood pressure after eating. In those cases, the drop in blood pressure may be caused by anti-hypertensive medications. Drugs aimed at lowering your blood pressure can sometimes be too effective and cause an unsafe drop.
The most serious complication related to postprandial hypotension is fainting and the injuries that can follow. Fainting can lead to a fall, which can cause a fracture, bruise, or other trauma. Losing consciousness while driving a car can be extremely serious. Reduced blood supply to the brain can also cause a stroke.
Postprandial hypotension is usually a temporary condition, but if low blood pressure becomes severe, some serious complications can result. For example, you can go into shock. If blood supply to your organs becomes significantly compromised, you may also experience organ failure.
If you regularly check your blood pressure and you notice a pattern of blood pressure dips after meals, tell your doctor at your next appointment. If the drops are accompanied by dizziness or other obvious symptoms, or if you regularly notice symptoms of low blood pressure after eating, then see your doctor as soon as you can.
Your doctor will want to review your medical history and symptoms. If you’ve been tracking your blood pressure with a home monitor, show your doctor the readings you have collected, noting when pressures were recorded after meals.
Your doctor should try to get a baseline pre-meal blood pressure reading and then a postprandial reading to confirm your home checks. Pressures may be taken at several intervals following the meal, starting at 15 minutes and ending at around two hours after eating.
In about 70 percent of people with postprandial hypertension, blood pressure drops within 30 to 60 minutes following a meal.
Postprandial hypotension may be diagnosed if you experience a drop in your systolic blood pressure of at least 20 mm Hg within two hours of eating a meal. Your doctor may also diagnose postprandial hypotension if your pre-meal systolic blood pressure was a least 100 mm Hg and you have a systolic blood pressure of 90 mm Hg within two hours of a meal.
Other tests may be administered to rule other possible causes of your blood pressure changes. These include:
- blood test to check for anemia or low blood sugar
- electrocardiogram to look for heart rhythm problems
- echocardiogram to evaluate the heart’s structure and function
If you take blood pressure-lowering medications, your doctor may advise you adjust the timing of your dose. Avoiding anti-hypertensive medications before eating may reduce your risk for a post-meal drop in blood pressure. Taking smaller doses more frequently during the day may also be an option, but you should discuss any changes in your medication timing or dosage with your physician before experimenting on your own.
If the problem isn’t related to medications, a few lifestyle changes may help. Some health experts believe that the insulin release that follows high-carbohydrate meals may interfere with the autonomic nervous system in some people, leading to hypotension. Insulin is a hormone that helps cells absorb glucose (sugar) from the bloodstream for use as energy. If you’ve been experiencing postprandial hypotension, track what you’re eating. If you regularly notice symptoms after high-carbohydrate meals, consider reducing your carbohydrate intake. Eating more frequent, but smaller, low-carb meals throughout the day may also help.
Walking after a meal may also help counteract a decrease in blood pressure. However, you should be aware that your blood pressure may drop once you stop walking.
You may also be able to keep your blood pressure up after a meal if you take a nonsteroidal anti-inflammatory drug (NSAID) before a meal. Common NSAIDs include ibuprofen (Advil) and naproxen (Aleve).
Having a cup of coffee or another source of caffeine before a meal may help, too. Caffeine makes blood vessels constrict. Don’t have caffeine in the evening, though, because it can interfere with sleep, potentially causing other health problems.
Drinking water before a meal may prevent postprandial hypotension. One study showed that drinking 500 mL — about 16 ounces — of water before eating lowered the occurrence.
If these changes aren’t effective, your doctor may prescribe the medication octreotide (Sandostatin). It’s a drug that’s usually prescribed to people who have too much growth hormone in their system. But it has also been proven effective in some people at reducing blood flow to the intestine.
Postprandial hypotension can be a serious condition, but it’s often treatable with lifestyle changes or an adjustment of your anti-hypertensive medications.
If you’re starting to notice symptoms after eating, tell your doctor. In the meantime, get a home blood pressure monitor, and learn to use it correctly. Tracking your numbers is one way to be proactive about this important aspect of your cardiovascular health.