The health of bowels is reflected in the characteristics of stool. Stools may also reflect the health of other organs of the body, such as stomach, pancreas, liver, and gall bladder. The characteristics of stool that are used to infer the health of gut and other organs include stool consistency, frequency of bowel motions, color of stools, and smell of stools. Apart from these characteristics, stools can also be examined in the clinical laboratory to reveal more details about the health of the body.
A feature of stools that can help distinguish between health and disease is whether the stool floats or sinks. In healthy conditions, the stools sink. Floating stools could indicate an underlying disease condition. However, this is not always the case. Not all incidents of floating stools indicate an underlying disease condition. Other accompanying signs and symptoms need to be taken into consideration before assuming that a disease may be present. If no other symptoms accompany floating stool, then there is usually no cause for immediate concern.
Why do stools float?
Floating or sinking is determined by the density of a substance, relative to the density of water. Stools float when they are less dense than water. This is mainly because of the presence of gas or fat within the stool.
Stools are composed of various components. Around 60-75% of the composition of stool is in the form of water. The rest of the stool components include undigested fiber (around 7.5%), intestinal bacteria (around 7.5%), inorganic components (up to 5%), fat (up to 5%), and a tiny fraction of protein (<1%). As can been seen from the composition of stools, gases do not form any significant fraction of stool. Therefore, even a slight increase in the fraction of gas in stool is enough to decrease stool density and make it float.
Floating stool may be caused by an underlying disease when it is accompanied by other signs and symptoms. These accompanying signs and symptoms could be diarrhea, abdominal pain, constipation, appetite changes, changes in consistency of stool, changes in color of stool, and changes in odor of stool.
Causes of Floating Stool
Gas in the intestine mostly comes from the action of bacteria in the colon. These colonic bacteria release gas as a byproduct of their action on food present in the intestine. Normally, the population of these colonic bacteria is kept in check. However, under certain conditions, there may be an increase in the number of colonic bacteria. Alternatively, certain conditions may cause incomplete digestion and absorption of food in the intestine. Both these conditions result in excessive gas production.
Gas in stool may also come from air that is swallowed while breathing, eating, and drinking. Carbonated drinks are a source of gas in intestine. Gas may also diffuse through the walls of bowel. Gas is also released during the process of chemical digestion. Unlike colonic bacteria, however, these are not major sources of gas in the intestine.
Diseases that cause floating stool are most commonly associated with abnormalities in gastrointestinal tract functions. Some of the common conditions that can result in floating stool include the following:
Infections of the bowel
Bowel infections, caused either by extrinsic pathogenic bacteria or intrinsic local bacteria of the intestine, are a major source of gas in the intestine. Under normal conditions, the growth of local bacterial flora of the intestine is kept in check. This is mostly achieved through the action of gut immune system and competition with other microbial flora. Under certain conditions, these growth checks can become lax, allowing bacterial overgrowth. This results in excessive gas production and floating stools.
Read more on gastroenteritis.
Food intolerance is caused by lack of appropriate enzymes that metabolize certain food components. A common example is lactose intolerance, which is a result of an absence of lactase enzyme. When a lactose intolerant person consumes milk and other dairy products, the lactose sugar in these foods is not digested. The bacteria in the intestine gets to feed on the undigested lactose sugar. This causes excessive gas production and floating stools.
Malabsorption refers to conditions in which nutrients from digested food are not absorbed in the intestine. Intestinal gas production increases as colonic bacteria act on the food components that remain in the colon. Malabsorption may result from different conditions, such as inflammation of intestine, intestinal infections, sensitivity to certain foods, and alcoholism.
Diseases of pancreas
The pancreas is an important player in the process of digestion. Pancreatic enzymes are released into the small intestine (duodenum), where they help in digesting various components of food. Diseases affecting pancreas can interfere with the synthesis and secretion of the pancreatic enzymes. Without the pancreatic enzymes, food in the intestine is not digested properly. Colonic bacteria feed on the undigested food and cause increased production of gases. This excessive gas production can contribute to the formation of floating stools.
Read more on pancreatitis.
Diseases of the gallbladder
The gall bladder secretes a fluid called bile into the intestine. Bile contains fat emulsifying substances, which enable fat-digesting enzymes to break down fats present in food. When bile production or secretion is affected (in conditions such as gall bladder disease or surgical removal of gall bladder), fat is not digested properly. The colonic bacteria feed on fat and increase in number. The resulting excessive gas production causes floating stools.
The whole length of the human intestine is involved in the digestion and absorption of various components of food. In conditions where the bowel length is shortened, the digestion and absorption of food is adversely affected. As a consequence, more food is available for the colonic bacteria. Increased bacterial action then leads to excessive gas production and floating stools. Short bowels can result either from surgical removal of a section of the intestine or due to a congenital condition.
Besides the above mentioned causes, excessive gas production and floating stools can also be caused by diseases such as celiac disease and cystic fibrosis. Normal conditions such as pregnancy and changes in dietary patterns (such as fasting and eating new foods) could also result in floating stools.