Gas is a normal bodily process that is expelled from the body through either burping (via the mouth) or flatulence (via the anus). Burping is typically caused by air being swallowed during eating, drinking, or talking, and may also be a result of carbonated drinks. The frequency and amount of burping varies from person to person and situation to situation.

Bad breath, or halitosis, can also be a result of gas expelled through the mouth, and may be caused by certain foods or underlying medical conditions such as acid reflux or poor oral hygiene.

Flatulence, on the other hand, is a more complex process involving a combination of food, gut bacteria, and colon transit time. Certain foods are known to be common culprits of excessive flatulence production, including vegetables, dairy products, beans, fruits, wholegrain foods, and soft carbonated and fruit drinks. However, the amount of gas produced from these foods can vary from person to person. Smelly flatulence is usually not indicative of a serious underlying medical condition.

Gastroesophageal Reflux Disease (GERD)

GERD is a condition in which the contents of the stomach, including partially digested food, reflux back into the lower esophagus, and in severe cases, up to the throat or mouth. This deposition of gastric contents in the mouth and throat can cause bad breath or halitosis.

Esophageal or Pharyngeal pouch

Pouches, also known as diverticula, are abnormal outward protrusions of the esophagus or pharynx wall. The presence of these pouches creates a space where food can accumulate instead of passing down the esophagus, leading to partial digestion and breakdown of the food material. This can result in the production of noxious gases, which can cause bad breath or halitosis.

Irritable Bowel Syndrome (IBS)

Irritable Bowel Syndrome (IBS) is a gastrointestinal condition that affects the normal contractions of the intestines and increases sensitivity to pain and gas distension. Common symptoms experienced by patients with IBS include bloating, abdominal distension, and frequent flatulence. The rate of intestinal transit can affect the frequency of flatulence passage, with accelerated transit causing more frequent passage and slower transit allowing for more time for the breakdown of faecal matter in the intestines.

Peptic Ulcers

Peptic ulcers are sores that form in the stomach or duodenum. When an ulcer bleeds, the blood is partially digested as it passes through the digestive tract, resulting in black, tarry stool with a distinct foul odor. This may lead to the production of smelly flatulence.

Lactose Intolerance

Many individuals of East Asian descent have a higher prevalence of lactose intolerance than other populations. This is because they have lower levels of lactase, an enzyme that breaks down lactose found in dairy products, in their small intestine. As a result, undigested lactose reaches the colon where it is fermented by bacteria, leading to symptoms such as abdominal pain, bloating, flatulence, and diarrhoea, which can also have a characteristic foul smell.

Constipation

Constipation occurs when faeces remain in the digestive tract for an extended period, particularly in the colon and rectum. This prolonged exposure to gut bacteria can result in excessive production of flatulence, which may have a distinct odour.