An estimated 30 to 50 million children and adults in the United States have a food intolerance condition called lactose intolerance, according to the University of Maryland Medical Center. People who are lactose intolerant are unable to digest milk and dairy foods properly due to the lack of an enzyme called lactase.

Standard colonoscopy involves the visual inspection of the rectum and large intestine by insertion of a flexible video camera through the anus. Approximately 5 to 10 percent of people report abdominal pain or discomfort after a colonoscopy, according to an October 2011 "Gastrointestinal Endoscopy"

Everyone's bowel habits, including the frequency, shape and color of movements, are different. When your bowel movements suddenly change to a very dark color, you might become alarmed. Color changes can indicate health problems, but think first about your diet. A number of foods can turn bowel movements dark.

Feeling ill, having the flu or suffering from vomiting and diarrhea can put a tremendous strain on your body. Symptoms may stem from a virus, food intolerance or food poisoning. Your body loses a large amount of fluids from throwing up and having diarrhea.

Cells within the stomach, known as the parietal cells, are responsible for the production and secretion of gastric acid. This acid is critical for breaking down food and for activating enzymes which are needed for digestion.

At some point in their life, most people experience acid reflux, more commonly known as heartburn. But for some, reflux is a common occurrence that causes significant discomfort. If chronic and untreated, reflux heightens your risk for more serious conditions, including Barrett’s esophagus and esophageal cancer.

Diverticulitis is the inflammation of diverticula, which are abnormal pouches that form on the wall of the colon. Diverticulosis is the condition of having many diverticula on the lining of the large intestine.

When your stomach hurts, everything you do is that much harder. The pain itself is distracting, as is worry over finding the cause. Acid reflux and ulcers are common ailments that can sometimes be confused, because both cause pain in the stomach area.

Something besides you loves to eat your food and drink your drinks: bacteria and viruses. When it comes to milk, leaving milk outside the refrigerator all day can contribute to food poisoning if your child drinks it.

A constant stomach ache and fatigue in a child might indicate several conditions. In most cases, the problems are a result of lifestyle choices or temporary illness. To determine the cause of the symptoms, note any other symptoms your child is having and how long the symptoms have lasted.

Cinnamon is a common spice -- many individuals experience heartburn every day, and cinnamon may be aggravating the symptoms for certain people. The most common symptom of heartburn or acid reflux is a burning sensation in the chest. This happens when acidic stomach contents back up into the esophagus.

A handful of almonds is a healthy snack rich in nutrients and antioxidants. Almonds are also high in vitamin E and magnesium, as well as a good source of fiber, which can help keep your digestion healthy. For some people, however, almonds can cause gastrointestinal problems, including the feeling of being bloated.