What Are the Causes of a Slow Digestive System?

If you've ever had slow digestion, you know how much the symptoms can decrease your quality of life. The nausea, the burping and the bloating can be too much to bear at times. So what causes slow digestion (a condition medically referred to as gastroparesis), and what can you do to help things along and improve the digestive tract?

The most common cause of gastroparesis is diabetes, but the condition can also go hand in hand with hypothyroidism, autoimmune diseases, disorders of the nervous system and infections. Certain medications can also make gastroparesis worse. Although you may not be able to completely resolve gastroparesis, especially if there's a chronic underlying medical cause, there are some things you can do to improve transit time.

Normally, when you eat, it starts a series of strong muscular contractions that help move the digesting food through your gastrointestinal tract. When you have a slow digestive system, a condition known as gastroparesis or delayed stomach emptying, these muscles don't work properly. They either contact too slowly or don't work at all and, as a result, your ​stomach doesn't empty​ properly.

The muscle contractions rely largely on the actions of several nerves and cells in your body, but one of the most important is a nerve called the vagus nerve. According to a report published in Frontiers in Psychiatry in March 2018, the vagus nerve is highly responsible for carrying various signals and message from the brain to the gut and vice versa.

This line of communication makes the vagus nerve a vital component in controlling the muscles in the stomach and small intestine. If the vagus nerve is damaged or stops working correctly for another reason, ​digestion slows down or stops​ altogether.

​Read more:​ Can Herbs Heal Nerve Damage?

Diabetes is the most known common cause of gastroparesis, and the connection between the condition and slow digestion has everything to do with the vagus nerve. One of the most common complications of diabetes is nerve damage, a condition medically referred to as diabetic neuropathy. According to the American Diabetes Association, almost half of all people with diabetes have some form of ​nerve damage.​

Diabetic neuropathy can affect any nerves in the body, but if it affects the vagus nerve, it can cause the digestive system to slow down. When diabetic neuropathy affects the digestive system (or the nerves of any other body system), it's more specifically classified as autonomic neuropathy. In addition to slowing down digestion, autonomic neuropathy can also affect bladder control and erectile function.

Although diabetes is the most common known cause of gastroparesis, other conditions can cause a slow gastrointestinal tract too. Other possible causes of slow digestion include:

• Hypothyroidism
  
• Parkinson's disease
  
• Multiple sclerosis
  
• Viral infection
  
• Previous abdominal or intestinal surgery
  
• Scleroderma
  
• Other autoimmune diseases
  

​Certain medications​ can also exacerbate gastroparesis and slow down stomach emptying even more. These medications include:

• Narcotic pain medications (codeine, hydrocodone, oxycodone, morphine)
  
• Antidepressants
• Anticholinergics (medications that block nerve signals and are commonly used as a treatment for gastrointestinal disorders, bladder dysfunction and nerve disorders)
• Pramlintide (a medication used to control blood sugar)

If your digestive system slows down, it can lead to various uncomfortable symptoms that negatively affect your quality of life. These symptoms may range from slightly bothersome to severe, depending on your current state of health and what kinds of foods you're eating. Signs and symptoms of gastroparesis include:

• Heartburn/acid reflux
• Bloating
• Nausea
• Vomiting undigested food within a couple of hours after eating
• Abdominal pain
• Belching
• Decreased appetite
• Feelings of fullness soon after starting a meal
• Feelings of fullness for a long time after finishing a meal
• Weight loss
• Uncontrolled blood sugar levels (especially in people with diabetes)
• Stomach muscle spasms

​Read more:​ The 10 Worst Foods for Acid Reflux

Although you might not be able to completely reverse gastroparesis, especially if there's permanent nerve damage that's developed as a result of diabetes, you can improve digestive tract function by changing what you eat and how you eat it. The Gastroparesis Clinic recommends eating about ​6 small meals​ spaced out throughout the day, rather than eating a lot of food at one time.

Splitting up your food intake can prevent you from becoming overly full, which can reduce nausea, vomiting and bloating after meals. ​Chewing your food​ really well can also reduce the amount of work that your stomach has to do during digestion and can make you more comfortable after eating.

It may also be helpful to avoid drinking fluids, which take up a lot of space in the stomach, with meals. When you eat and drink at the same time, your stomach fills up really quickly. For those with gastroparesis, this can be really uncomfortable. Try drinking fluids at least an hour before or after meals instead of during your meals.

In addition to eating smaller meals, spending more time chewing your food and separating your drinks from your meals, there are some other ​lifestyle changes​ you can make to speed up digestion and make living with gastroparesis more bearable. These are some things you can do:

• Don't lie down within an hour after eating.
  
• Avoid high-fat foods (which further delay stomach emptying). Examples include fried foods, butter and oils and full-fat dairy products.
• Limit insoluble fiber (which further delays stomach emptying). Examples include raw vegetables, bran and fruit with the skin.
• Eat a soft diet. Examples of soft diet foods include yogurt, cooked vegetables and casseroles.
• Avoid carbonated drinks.
• Drink plenty of water (in between meals).
• Incorporate gentle exercise, like walking, after eating.

If your gastroparesis is a result of diabetes, you may be able to improve your symptoms by getting your blood sugar under better control since high blood sugar can cause further delays in stomach emptying, according to a July 2014 issue of Today's Dietitian. You can manage your blood sugar by avoiding sugar and reducing your overall carbohydrate intake. Of course, always discuss any lifestyle changes with your doctor before incorporating them.